TIDBITS OF INFO- GENERAL SCIENCE

rehab · TIDBITS OF INFO- GENERAL SCIENCE

Analyzing Ores With The Spectrograph

In a previous article some of the applications of spectrography to mining were discussed. It is proposed here to explain how these analyses are made so that the engineer, or mining man may see for himself wherein this method may furnish the solution to many specific problems.

Many are familiar with the simple flame tests that are frequently used in field assaying, by which preliminary qualitative determinations on ore samples are made. When an intense flame is applied to a small amount of the sample, as in the case of a copper ore, a bluish-green flame reaction is observed. On the other hand, an ore containing large quantities of sodium gives an intense yellow flame.

Other metals also give characteristically colored flames when treated in this manner, showing that the colors emitted are closely associated with definite substances. In fact upon analyzing such light with suitable instruments, it is found that each metal emits a series of colors or wavelengths that are absolutely characteristic and remain unchanged regardless of the chemical combination or physical condition the metal may have. The eye in recording the stronger of these colors affords the crude flame-test method of identification.

With these fundamentals in mind, it is easy to see that by employing an Instrument, in place of the eye, capable of classifying the wave lengths of light emitted from an unknown ore, it is possible to determine each of its constituents.

Both the spectroscope-a visual instrument, and the spectrograph, a photographic instrument, have the ability to break up complex light into its elemental components in much the same way that a simple prism disperses sunlight into its spectrum.
In fact many of the instruments employ prisms for that purpose, while others use gratings to achieve the result. Both of these types lend themselves to the photographing of the spectrum in a single operation. This greatly extends the range of usable wavelengths since both the invisible ultra-violet and infra-red regions of the spectrum ma y be photographed.
This is particularly fortunate since many of the most sensitive wave lengths of the various elements lie in the ultra-violet which makes possible their detection, if present, to as little as one one-thousandth of a per cent.
In practice the application of the spectrographic method of analysis proves to In the laboratory, to excite the spectra, or in other words produce light, the material is usually burned in an electric arc. This arc is struck between two chemically pure electrodes, the lower of which is cored with the finely ground sample to be investigated.

Upon starting the arc, a temperature of 7,000 to 10,000 degrees Fahrenheit is obtained which rapidly volatilizes all of the mineral constituents and brings them into the flame in the atomic form. Here the atoms, bombarded with electrons, are excited and made to give off light characteristic of those atoms or elements, as mentioned above. This light when dispersed and photographed, furnishes a complete record or spectrogram of the elements present in the ore,

The spectrogram records the light produced by the different elements as fine vertical planes whose positions are determined by the wavelengths of that light. Since tables of the principle lines’ of all the known elements are available, it is a simple matter to determine the elements such as beryllium, copper, silver and so on, which produced the lines recorded by the photograph.

With a suitable instrument, the lines representing the various metals, or elements do not interfere with one another, and since a number of lines for each element may be checked, the method is absolutely certain in identifying these substances in a spectrum.

In addition to giving qualitative information, the spectrograph also affords quantitative estimates. There is a definite relation between the intensities or blackness of the photographed lines found in the spectrum of a certain ore and the amount of the element producing them. Thus, by measuring line intensities, quantitative estimates can be made.

As for example, if lines associated with silver are found to be quite faint, it would indicate a quantity of about one part in a million, while heavier lines would signify correspondingly larger quantities. Through experience it is possible to estimate whether the value is close to 10, 1, .1, .01 or .001 per cent as the case might be. Therefore it is possible from a single spectrogram, taken of the sample burning in an electric arc, to deduce practically all of its elements, and to estimate the quantities in which they are present.

That this method will have far-reaching effects on analytical problems in general is certain, and that there is a real place for it in mineralogy may be seen from this discussion. The scope of the method in connection with various types of ore analysis will be covered in the next article of the series.

rehab · LUMINOUS PRESSURE WAVES EMJ 8 25 1928

Luminous Pressure Waves

PHOTOGRAPHS of the explosion taking place when a cartridge of dynamite is detonated have shown the existence of luminous waves propagated at high speed in the air surrounding the explosive. It was at first thought by U. S. Bureau of Mines engineers conducting these experiments that the waves were merely reaction gases projected from the explosive, but further work in which the air around the stick has been replaced by hydrogen or carbon dioxide has made it seem probable that these are really pressure waves at such high temperatures that the gas actually radiates in the visible region of the spectrum. The work is part of a program of investigation by the Bureau of Mines of the sensitivity of explosives to detonation by influence.

Engineering and Mining Journal— Vol.126, No.8

rehab · MINING AND METALLURGY EMJ 9 28 1922

September 28, 1922 Engineering and Mining Journal-Press 641

An Illustrated History of Mining and Metallurgy IV*
In Sixteenth Century America—Practices of the Incas and Improvements by the Spaniards —The Discovery of Potosi—Acosta Describes the Amalgamation Process and the useof Quicksilver in Smelting Silver

By H. H. MANCHESTER

WHEN THE SPANIARDS discovered Central America, Mexico, and Peru they found the natives using gold much as they did copper, and valuing it little if any more highly. Silver also was in use, but the natives knew nothing of iron, and when first made presents of iron hatchets, and other tools, valued them more highly than they did gold because of their greater usefulness.

The Incas had pots, cups, flagons, and even chairs and litters of gold, to say nothing of many images of their gods. This was not because they valued gold more highly, but because it was capable of being easily worked into such forms.

The methods of mining were very simple. Peter Martyr says that in getting gold from streams, the Indians simply gathered up the sand in their hands, and shifted it from one hand to the other until most of the sand flowed out.

The Incas smelted by means of furnaces without any chemical processes. They used blowpipes, though not bellows, avoiding the employment of the latter by placing many of their furnaces on the side of a hill where the wind would blow the fire. The blowpipes were used more for the small furnaces in which the metal was melted so that it might be cast.

Spain, it will be remembered, was the greatest source of precious metals in ancient times, and the Spaniards had no sooner discovered America than they began to look for gold and silver there. They started mining on the Isthmus, at Darien, about 1514. Oviedo, who wrote in 1526, said that he had been for twelve years “surveyor of the melting shops pertaining to the gold mines of the main land.”

At first, the king’s share was one-fifth, but in 1526 it was temporarily reduced to one-tenth of the products of the mine, and by subsequent re-enactments this continued to be the royal tithe.

At the same time mining was made open to both Spaniards and natives, and. attempts, though not always successful ones, were made to protect the natives. Slaves were early introduced, and formed a distinct class from the Indians themselves.

Oviedo wrote that in mining on land, the dirt was carried from the mine in trays to the stream where it was delivered to washers. These were for the most part Indian women, who were wont “to sit by the water’s edge with their legs in the water even up to the knees,” and thus pan the pay dirt.

But more important than the gold mines discovered by the Spaniards in Central America, Mexico, and Peru, were those of silver. Even before the discovery of America, the Incas made the mines at Porco produce large quantities of silver. A tremendous impetus to silver mining was given by the discovery of silver at Potosi, Peru, in 1545.

The story is that this came about as follows:

A Peruvian by the name of Gualpa, who worked in the mines of Porco, went hunting one day, and it chanced that the game ran up the steep mountain of Potosi. He attempted to follow it by taking hold of one scrub after another, but eventually his weight pulled a bramble, called quinua, out by the roots. It seemed very heavy, and looking down he saw a great lump of silver hanging to it.

Examining the hole he discovered a large vein of silver ore, which upon being smelted at his home he found’ to be of the highest grade he had ever known. He worked his mine secretly for some time, but at last his evidently increasing wealth excited the suspicion of his neighbor, Guanca, who forced him to disclose the secret, and started working a near-by vein.

As the metal did not come from this so easily, Guanca told his Spanish master, Vilarroel, who in turn registered the mine, and, in accordance with the mining law, obtained several rods to work for himself.

The best description of sixteenth century mining in America is given by Acosta, who after spending a number of years in Peru, returned to Spain in 1587, and in 1590 wrote in ‘Spanish his “Natural and Moral History of the Indies.

According to Acosta, the most famous gold was that of Carovaya, in Peru, and Valdivia, in Chile. An idea of the quantity of gold produced may be gathered from his statement:
“In the fleet in which I came to Spain, which was in the year 1585, the declaration of the mainland was twelve cassons or chests of gold, every casson weighing at least four arrobas, that is a hundred weight, and 1,056 marks from New Spain which was for the king only, besides that which came registered for merchants and private men, and much that came unregistered.”

Since the mines of Potosi were of such tremendous importance, Acosta paused to give quite a description of them, from which we may abstract the following account:
The rock of Potosi contained four principal veins running north and south, besides various lesser veins running from the main lodes like branches on a tree. By 1585 the mines were deep for that period.

In one vein at Potosi were reckoned seventy-eight mines which were 100 fathoms deep, and a few which were 200 fathoms. In another vein were twenty-four shafts, some from 70 to 80 fathoms deep. To facilitate working at this depth, the Spaniards constructed tunnels called soavones, which were begun at the foot of the mountain, and ran horizontally to meet the vein.

These were a fathom in height and eight feet in width. One of these tunnels was begun in 1556, and required twenty-nine years to construct. In 1585 this was driven 3,500 ft. into the mountain, and met the mine shaft 185 fathoms below the top. There were already nine tunnels completed and others begun.

Acosta’s description of the work in the mine is too vivid not to be quoted:

“They labor in these mines in continual darkness and obscurity, without knowledge of day or night. And forasmuch as those places are never visited with the sun, there is not only a continual darkness, but also an extreme cold, with so foul an air contrary to the disposition of man, that such as newly enter are sickening

as they are at sea.

The which happened to me in one of these mines, where I felt a pain at the heart, and heating of the stomach. Those that labor therein use candles to light them, dividing their work in such sort, as they that work in the day rest by the night, and so they change. The metal is commonly hard, and therefore they break it with hammers; splitting and hewing it by force as if they were flints.

Afterwards they carry up this, metal upon their shoulders, by ladders of three branches made of neats leather twisted like pieces of wood, which are crossed with staves of wood, so that by every one of these ladders they mount and descend together.

They are ten estados long apiece, and at the end of one, begins another of the same length, every ladder beginning and ending at platforms of wood, where are seats to rest them like unto galleries, for that there are many of these ladders to mount by, one at the end of another.

A man carries ordinarily the weight of two arrobas of metal upon his shoulders, tied together in a cloth in manner of a skippe, and so mount them three and three. He that goes before carries a candle tied to his thumb, for, as it is said, they have no light from heaven, and so they go up the ladder holding it with both their hands; to mount so great a height which commonly is above 150 estados—a fearful thing which breeds an amazement to think upon it, so great is the desire of silver, that for the gain thereof men endure any pains.”

Acosta also gives an interesting account of the earliest known American smelting. lie says the Indian method was by dissolving the metal by fire. “To’ this end,” says Acosta, “they built small furnaces where the wind commonly blew, and with wood and coal made their refining, the which furnaces in Peru they called huayras.”

The Spaniards had at first also used such huayras, which were best for refining the richest ores. Later they learned to use the process of amalgamation with quicksilver.

The method there employed is described by Acosta as follows:
“They first beat and grind the metal very small, with the hammers of the machinery, which beat this stone like unto ten milles, and being well beaten they ‘searce’ it in a copper ‘scarce,’ making the powder as small and fine as if it were horse hair; these ‘searces’ being well fitted, do sift 80 quintals in a day and a night; then they put the ponder of the metal into the vessels upon furnaces, whereas they annoint it and mortify it with brine, putting to every 50 quintals of powder, 5 quintals of salt.

And this they do for that the salt separates the earth and filth, to the end the quicksilver may the more easily draw the silver unto it. Afterwards they put quicksilver into a piece of holland and press it out upon the metal, which goes forth like a dew, always turning and stirring the metal, to the end it may be well incorporated.

“Before the invention of these furnaces of fire, they did often mingle their metal with quicksilver in great troughes, letting it settle some days, and did then mix it and stir it again, until they thought all the quicksilver were well incorporate with the silver, the which continued twenty days and more, and at the least nine days.

“Since they discovered, as the desire to get is diligent, that to shorten the time fire did much help, to incorporate silver the sooner with quicksilver, they invented these furnaces, whereon they set vessels to put in their metal with salt and quicksilver, and underneath they put fire by little and little in furnaces made for the nonce underneath; so that in five or six days the quicksilver is incorporate with the silver.

“And when they find that the mercury hath done his part, and assembled all the silver, leaving nothing behind, but is well imbrued, as a sponge doth water, dividing it from the earth, lead, and copper, with which it is engendered, then they separate it likewise from the quicksilver, the which they do in this sort; they put the metal in caldrons, and vessels full of water, where with certain wheels they turn the metal round about, as if they should make mustard, and so the earth and dross go from the metal with the water that runs away.

The silver and quicksilver as most ponderous remaining in the bottom, the metal which it remains is like unto sand. Then they take it out and wash it again in great platters of wood, or kettles full of water, still drawing the earth from it, until they leave the silver and quicksilver well cleansed. There slips away also some small portion of silver and quicksilver with the earth and dross, which they call washings, then which they wash again and draw out the remainder.

“When the silver and quicksilver are cleansed and begin to shine, and that there remains no earth, they put all the metal into a cloth, which they strain out very forcibly, so that all the quicksilver passeth out, being not incorporated with the silver, like to a mark of almonds pressed to draw oyle. And being thus pressed, the remainder contains but the sixth part in silver, and five in mercury. So if there remains a mark of threescore pounds, ten are of silver, and fifty of mercury. Of these marks they make pinczs, as they call them, like pine apples or sugar loaves, hollow within, which they commonly make of a hundred pound weight.

“Then to separate the silver from the quicksilver, they put it into a violent fire which they cover with an earthen vessel, like to the mold of a sugar loaf, or unto a capuchon or hood, the which they cover wit coals, and set fire unto it; whereby the quicksilver exhales the smoke, which striking against the capuchon of earth, thickens and distills, like unto the smoke of a pot covered; and by a pipe, like unto a limbecke, they receive the quicksilver which distills the silver remaining without changing the form, but in weight it is diminished five parts of that it was, and is spungious, the which is worthy of observation.

Of two of these loaves they make one barre of silver, in weight 65 or 66 marks; and in this form they carry it to the touch, custom, and mark. Silver drawn with mercury is so fine, that it never abates of two thousand three hundred and fourscore of alloy.”

Both stamp mills and grinding mills were used at Potosi, and they were driven by either horsepower or water-power. It rained only during the winter there, and the rain had to be stored in reservoirs for use in the summer months. If necessary, however, the ore could be carried three or four leagues to Tarapaya, where power was fur-. nished by a river.

The use of quicksilver in smelting was of course not known to the Incas, but they did have mines of vermilion, from which they made paint for decorating themselves. A Portuguese named Henrique Garces, who had known of vermilion in Castile, suspected this to be the same as that from, which mercury was extracted, and upon examining the mine, found this to be the fact.

The application of quicksilver to smelting in Peru was credited to Fernando de Velasco in 1571. Its success increased demand for quicksilver. This naturally led to a great smelting of this as described by Acosta as follows:
“Let us now speak of how they draw out quicksilver, and how they refine silver therewith.

They take the stone or metal where they find the quicksilver, which they put into the fire in pots of earth well luted, being well beaten, so that this metal or stone coming to melt by the heat of the ‘fire; the quicksilver separates itself, and goes forth in exhalations, and sometimes even with the smoke of the fire, until it encounters some body where it stays and congeals, and if it pass up higher, without meeting of any hard substance, it mounts up until it be cold, and then, congealed, it falls down again.

When the melting is finished, they unstop the pots and draw forth the metal, sometimes staying until it be very cold, for if there remained any fume or vapor, which should encounter them that unstopped the pots, they were in danger of death, or to be benumbed of least to loose their teeth, their limbs, or fat.”

*The fourth and last of a series of articles. The first, second and third articles of the series were published in the issues of Sept. 2, sept. 9, and Sept. 18. respectively.

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Manufacture of Hollow Drill Steel
An iron bar with a hole through the center is stronger than a solid bar of the same diameter. According to the Queensland Government Mining Journal “a British firm has developed a very ingenious process of making what it calls a hollow-cored bar with this increase of strength. The hollow core is really a small hole which extends from end to end of the bar. Obviously it would be a very costly business to bore a hole through the bar, and in consequence this firm has developed a clever way of making the bar hollow without drilling. The mass of metal from which the bar is drawn is drilled in the first case, and the hole is packed tight with a special composition. The ends of the hole are subsequently sealed by a patented process of welding. When the piece of metal is rolled in the mill into a long bar the packing stretches with the metal and preserves the continuity of the hole. One of the most important applications of this hollow-cored bar is for mining drills where the hole is used for a current of air or a jet of water.
In the United States, hollow drill steel is commonly made by drilling a hole, say 1* in. in diameter, in a steel billet about 18 in. long by 5 in. in diameter. This bole is then packed with sand and the ends are plugged with steel plugs before the billet is drawn down to the required size. In some special steels, a mandrel with a manganese steel tip is used, followed by hot punching to secure a more uniform hole.

rehab · MINING HISTORY LINKS

Copper and AZ mining history:
http://www.azcu.org/cumightymetal/

Arizona Official mining depts. and publications
http://www.admmr.state.az.us/onlineres.htm

links for mineralogists
http://www.uni-wuerzburg.de/mineralogie/links/ore/ore.html

Western mining history links
http://www.westernmininghistory.com/

gold history links
http://www.goldsheetlinks.com/history.htm

rehab · FUNDAMENTALS OF FLOTATION TMJ 10 15 1929

THE MINING JOURNAL OCTOBER 15 1929

STUDYING THE FUNDAMENTALS OF THE FLOTATION PROCESS

The application of the flotation process in metallurgy has, as is well known, resulted in the recovery of millions of dollars worth of metals that would otherwise have been lost. A continuous study of advances in the art of flotation is conducted by the United States Bureau of Mines, which has made significant contributions to the development of this process, and its successful application, in the treatment of various types of low-grade and metallurgically difficult ores. Much of the Bureau’s investigative work in flotation is conducted at the Intermountain Experiment Station. Salt Lake City, Utah, in cooperation with the Department of Mining and Metallurgical Research of the University of Utah. Two publications containing the results of these cooperative investigations have recently been issued by the University of Utah as Technical Papers 4 and 5 in a series of reports devoted to the subject of “Flotation Fundamentals.”

Technical Paper 4, by A. M. Gaudin and Paul M. Sorensen, gives the results of tests on the flotability of pure chalcocite. They represent an extensive investigation of the effect of various collectors and depressors on the flotation of chalcocite. Complete depression of chalcocite is accomplished by the addition of small quantities of thiosulphate, sulphite, sulphide, ferrocyanide, or ferricyanide ions. Some reagents react with the collector in such a way as to destroy its usefulness and should be avoided. The effects of some common anions are discussed. An-ions that form insoluble copper salts inhibit the flotation of chalcocite.

Technical Paper 5, by A. M. Gaudin and J. Sheldon Martin, describes the flotation of malachite and azurite. It was found that:
Malachite and azurite can be floated from a siliceous gangue by means of suitably selected saturated fatty acids and fatty acid soaps. Saturated fatty acids and fatty soaps will not effect a separation of the carbonates of copper from a calcite gangue.
Failure of the fatty acids and fatty acid soaps, in the flotation of malachite and azurite from calcite, has been shown to be due to the acid condition of the circuit, which results in copper and calcium ions being present in the solution, causing the formation of identical surfaces on both the copper and the calcium carbonate particles.
Several nitrogen-containing organic substances, such as amines and hydrazines, have been investigated as collectors of malachite and azurite. These compounds will float the carbonates of copper from calcite, but relatively large amounts are required.
Organic nitrogen-sulphur reagents, such as the thio-carbonates, are more powerful collectors of malachite and azurite than are compounds containing nitrogen, but no sulphur.
The effect of a large number of xanthates, and other thio-carbonates, on the flotation of malachite and azurite from calcite, and other common gangue minerals, without previous sulphidizing, has been investigated.

It has been shown that the xanthates and thio-carbonates collect as a result of the formation of insoluble copper compounds, with the copper carbonates, by chemical reaction rather than by adsorption of the reagent molecules on the mineral surfaces.
Malachite and azurite may be floated from calcite, and other gangue minerals, by means of relatively small amounts of suitably selected xanthates and other thiocarbonates.
Temperature, time of conditioning of the mineral with reagents, and grain size are important factors affecting the flotation of the copper carbonates with the xanthates and thio-carbonates.
An investigation of the effect of several organic hydrosulphides has shown that this type of reagent can be used to float malachite and azurite from calcite and other gangue minerals.
The organic hydrosulphides are collectors of malachite and azurite by reason of the fact that insoluble copper mercaptides are formed on the surface of the copper carbonate particles by chemical reaction involving the replacement of hydrogen by copper in the hydrosulphide molecule.

The amount of reagent required in floating the copper carbonates depends to a large extent upon the quantity of copper carbonate present.
The results of this investigation seem to indicate that copper carbonate ores may be concentrated by flotation by the use of suitably selected thio-carbonates (xanthates), or by means of organic hydrosulphides (mercaptans).
It should be borne in mind that the freshness and purity of the mineral used in investigations of this character must be known before any dependence can be put on results obtained and interpretations made. Differences in the behavior of minerals from different localities, and in different ores may largely be the result of variations in the freshness or cleanliness of the surfaces of the mineral grains.

Technical Papers 4 and 5, relating to “Flotation Fundamentals,” may be obtained from the University of Utah, Salt Lake City, Utah, at prices of 25 and 35 cents, respectively.

============
The United States, the largest consumer of tin among the nations of the world, produces from its own mines practically none of this essential metal. The United States takes upwards of 52 per cent of the world’s production.

rehab · SPONGE IRON USE TO RECOVER COPPER AND LEAD TMJ 10 15 1929

THE MINING JOURNAL OCTOBER 15 1929

PRECIPITATION OF LEAD AND COPPER BY USE OF SPONGE IRON

The porous properties of sponge iron have been utilized by the Department of Commerce, in a series of experiments, looking toward the improvement of the process of precipitation of lead and copper from solution. The sponge iron is substituted for coarse scrap iron, which is relatively awkward to handle, and exposes only a small amount of surface to pregnant solutions.

Products containing more than 80 per cent of lead were made, and valuable information relative to the precipitation of copper from various solutions was obtained. The experimental work was conducted at the Southwest Experiment Station of the United States Bureau of Mines, Tucson, Arizona, and at the Bureau’s Intermountain Experiment Station, Salt Lake City, Utah, under cooperative agreements with the University of Arizona and the Department of Mining and Metallurgical Research, of the University of Utah.

The results of the experiments are described in Bulletin 281, by G. L. Oldright, H. E. Keyes, Virgil Miller, and W. A. Sloan, issued by the Bureau of Mines. The study was largely one of the rates of diffusion of the metal ions in the solution, and through the metallic coatings surrounding the sponge iron particles. In order to completely remove the valuable metals from solution, and at the same time to obtain a precipitate of good grade, the precipitant should be almost completely consumed. These practical ends are usually accomplished by having the two substances involved pass each other counter-currently.

Experiments on lead precipitation, showed that vigorously stirred solutions should be heated to 60 degrees Centigrade in order to precipitate the metal in less than one hour. The rate of precipitation varied as the amount of lead remaining in solution only when the amount of iron added was just that required stoichiometrically to replace the lead.

A large excess of sponge iron precipitated all of the lead from solution, but enrichment of this precipitate by subsequent exposure to an excess of fresh, rich solution was difficult. Porous and pure varieties of sponge iron, reacted much faster than those that were dense and impure.
Too rapid stirring caused “balling” of the lead coated sponge iron. This was prevented by slowly rabbling the sponge iron downward, over a series of superimposed trays in a cylindrical tank counter-currently to the solution.

The use of iron as a precipitant for copper is very old, and machines of many types have been employed. The present study was undertaken to determine the effect of different variables on the precipitation. It showed that an excess of 7.5 per cent of metallic iron over that required stoichiometrically to precipitate the copper was usually sufficient, and little advantage was gained by adding an excess of over 15 per cent. Whether the sponge iron was added in stages or all at the start made little difference. Often over 80 per cent of the metal was replaced from solution, in 2 to 4 minutes. An increase in acidity decreased the rate of copper precipitation in the richer copper solutions, but increased it in the poorer solutions, when the amount of sponge iron present was 7.5 per cent in excess of the chemical equivalent. The amount of metallic iron dissolved increased for the richer copper solution,and decreased for solutions poorer in copper with an increase in acidity and varied with the kind of iron used. Evidently there was an interrelationship between the rate of dissolving the iron and the rate of precipitating the copper.

Only a negligible amount of copper was dissolved by sulphuric acid in the absence of air. When air was admitted, the addition of ferrous sulphate to the acid solution slowed down the rate of dissolution. The dissolution of the copper was probably due to its direct atmospheric oxidation with subsequent dissolving of the oxide in sulphuric acid, rather than to the agency of ferric salts.

When a constant amount of metallic cement copper was added to a solution agitated in an open beaker, the more acidic the solution the greater was the percentage of copper dissolved. The number of grams of copper dissolved per minute, per percent of acid, was approximately constant up to the time of neutralization of all of the acid. With a ratio of 3 to 2 between copper and acid, the dissolving rate of the copper was fastest when the acid content was between 10 and 16 grams per liter, although the amount of air admitted and the size of the bubbles greatly influenced the rate.

Where the re-solution of the copper on account of the admission of air was not serious, the metal could be precipitated almost completely in 15 to 25 minutes with an amount of sponge iron 7.5 per cent in excess of the theoretical equivalent.

Detailed information in regard to these studies is contained in Bureau of Mines Bulletin 281, “Precipitation of Lead and Copper from Solution on Sponge Iron,” which may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C., at a price of 35 cents.

rehab · COPPER LEFT IN CONVERTER SLAG TMJ 10 15 1929

BUREAU STUDIES THE FORMS OF COPPER IN CONVERTER SLAG

A study of the forms of copper in converter slag, has been completed by the Southwest Experiment Station of the Bureau of Mines, Tucson, Arizona, in cooperation with the University of Arizona. The work was undertaken to get information indicative of the technical practicability, or impracticability, of possible mechanical methods of removing the copper from converter slag. A successful mechanical method would make possible the discarding of the converter slag without returning it to the reverberatory.

Some of the conclusions derived as a result of the investigation were:

In the whole slag product obtained in converting a matte containing 30 per cent copper, about 10 per cent of the copper in the slag is in the oxidized form; the remainder is in the form of metallic copper and sulphides. The first skimmings are low in oxidized copper, the proportion of which decreases as the white metal stage approaches.

The particles of sulphide are so small in a chilled slag that they are not all freed even by grinding to pass 350 mesh.

If the molten slag is allowed to cool slowly, so as to develop a crystalline structure, the size of sulphide particle is increased greatly, so that grinding to pass 150 mesh will free the sulphides almost completely. The crystalline slag is much easier to grind than chilled slag.

Cleaning of slowly-cooled crystalline converter slag by flotation is probably technically feasible.

rehab · VENTILATION KEY TO PRODUCTIVITY TMJ 10 15 1929

THE MINING JOURNAL OCTOBER 15 1929

For Superintendents and Managers Only
By LETSON BALLIET, Tonopah, Nevada

(Stockholders, please do not read this —you’ll faint if you do— the air is bad, and your dividends are less than they might be.)

Ventilation in mines is just as important to the owner and operator as to the worker. Coal mine foremen and bosses are required to pass an examination on ventilation, including the passing of gasses through air conduits and entries, but not so with the metal miners. Usually they install a blower of some kind and add to it as they find need for more air. They never think of vacuum bottles and air analyses, and most of the smaller operators know nothing about them. Making air pass in the direction desired, and through various workings is seldom attempted by metal miners.

I recall two serious underground mine fires, one caused the death of a score of miners fighting fire, because the air current was reversed, by spraying water down the upcast shaft and cooling it until it became heavier than the warm air in the downcast shaft, and reversed the current. It smothered the fire fighters, who were working on the downcast side, before the air current was reversed. No coal operator would have done that. He would have known that chilling the upcast shaft would reverse the air. The other fire killed two score men because the air current was not reversed.

But aside from that, let us consider ventilation from another angle, and try an experiment.

Take any group of miners out on the surface of the mine on a cool morning and offer $5 to the one who can hold his hand extended at arms length, palm upward, with a dine on it, for the longest time, or offer them all 10 cents a minute, for the first five minutes, 20 cents a minute over five minutes and 30 cents a minute over ten minutes, and make a record of the length of time each man can hold out his arm.

Then take them underground in dead ends and hot stopes, and offer them double the prize if they equal their surface record. Not one single man can do it. At a temperature of 90 degrees with high humidity, not one can hold his arm extended for half the time. In this test it will be well to remember that the workman is standing still, and is not violently exercising and yet he does less than half the work he did in good ventilation.

For an exertion test, give two men five tons each, of broken rock to shovel over a four-foot rail onto the dump. Give a prize of $20 to the one who does it in the least time. The next day when the men are rested, take the same two men underground, where the humidity and the temperature are high and ventilation poor, and offer them $100 if they’ll shovel five tons over a four-foot rail, down some old stope, or chute, in the same time. It will require triple the time to do the work. The men are doing but one third of the work and suffering more.

At $5 a day wage scale, how much are you losing when you pay three men to do one man’s work?

If it requires 300 men to do 100 men’s work, at $5 a day, the extra 200 men are costing $1,000 a day or $365,000 a year, which sum would pay for a little improvement in ventilation, and pay for some one who understood mine ventilation to arrange it.

What the average man will do, in eight hours at his normal rate of speed in good air is at least thrice as much as he will do in hot, humid, poor air, but you are paying the bill, and it’s your reputation for economic production. Try the experiments and see for yourself.

rehab · BEGINNING OF OPEN PIT MINING TMJ 10 15 1929

THE MINING JOURNAL for OCTOBER 15, 1929

IMMENSE TONNAGES ARE MINED BY STRIPPING METHOD

The popular conception of a mine, is a maze of underground workings, from which useful minerals are won at considerable depths below the surface of the earth. Open-pit methods of mining, by which coal or ore is mined from the surface by the use of monster steam or electric shovels, has, however, been developed to a point where during an average year approximately 19,000,000 tons of coal, 24,000,000 tons of copper ore, 32,000,000 tons of iron ore, 150,000 tons of bauxite, and 2,700,000 tons of pebble phosphate are mined in the United States in this manner. These quantities total 78,000,000 tons, and at least four times that amount of overburden is stripped to expose these minerals for mining.

The great power shovels used in the stripping operations range in dipper capacity from 3 to 12 cubic yards, weigh 125 to 850 tons, and may cost $100,000 or more. A 15-yard shovel, weighing 1,300 tons, has recently been designed. The increase in open-pit mining operations, with consequent demand for information on methods and costs of stripping, has caused the United States Bureau of Mines to conduct an investigation of the subject.

Stripping as a method of mining dates back to the early mining of coal, when overburden was removed by pick and shovel, loaded into wheelbarrows or carts, and dumped, states F. E. Cash, and M. W. von Bernewitz, in a bulletin just published by the Bureau of Mines. Some of the early wheelbarrow runs and dumps can yet be seen in the anthracite districts of Pennsylvania. When the overburden became too heavy to move by hand, horses with plows and slip scrapers were used; and later came wheeled scrapers for heavier work, or thicker overburden.

Much of the development of the coal-stripping industry has taken place in the Danville District, Illinois, where small pits were opened in 1866. Pittsburg, Kansas, also was the scene of early coal-stripping operations. In 1897 the first steam shovel was introduced into the iron range of Minnesota. In 1906 stripping of copper ore with steam shovels was started at Bingham, Utah. Approximately twenty thousand men are employed in strip-mining operations in the United States at the present time.

Bituminous coal is stripped of its cover and mined in 20 states of the Union. The total production by stripping operations is growing, particularly in Indiana, Illinois, Missouri, Oklahoma, Montana, and North Dakota. This output is equal to about 3 per cent of the total coal produced in all states. The strip mines range in capacity from a few hundred to several thousand tons a day.

The capital required to purchase and equip a strip mine is large. The land may cost $100 to $500 an acre; a 6 or 8-yard stripping shovel costs $99,000 to $158,000, and a loading shovel $15,000 to $26,000; locomotives cost $6,000 and up; track costs $27 to $43 a ton (about $2,000 a mile); dump cars cost $400 and up; and a tippel may cost $3,000 to $130,000, depending on the amount of machinery installed. This equipment has to be placed, and considerable overburden removed, before the mining of coal can be commenced. It is essential also that the coal be picked and screened before it is shipped to consumers.

Anthracite has been stripped somewhat irregularly, but the yearly total exceeds 2,000,000 tons. In all, an enormous amount of cover and coal has been removed. Stripping is being done in the Northern, Eastern-middle, and Western-middle fields of Pennsylvania. The cost of stripping and mining ranges from $1.85 to $4.91 per ton of coal produced.

Bituminous coal mining in strip pits has made increasing strides, partly because of economic factors, partly because of the comparative simplicity of operations, and partly because of the great improvement in equipment, which has helped to reduce costs. Electric stripping shovels of capacity as high as 12 and 15 yards, 3-yard electric loading shovels, trains with 15 to 40-yard dump cars, liquid oxygen explosive, modern tipples, and a daily production of up to 5,000 tons of coal are some of the features of bituminous strip mines.

The cover is 15 to 60 feet in thickness. At one mine in Wyoming, the cover is removed successfully by hydraulicking. In Illinois and Indiana, part of the cover at two mines, is removed by drag lines and shovels in tandem. The coal beds are 18 to 84 inches in thickness, although 22 feet are being mined in Montana and 79 feet in Wyoming.

Lignite is mined in North Dakota and Texas, and stripping practice is reported to be improving, particularly in the former state, where conditions are generally favorable.

The stripping and mining of copper ore, represents a highly developed and extensive phase of the mining industry. In a recent year 60 shovels stripped at least 16,000,000 yards of capping, and 24,000,000 tons of ore in 30 to 70-foot benches in mountainous country.

Iron ore has been stripped and mined for years on an enormous scale. As a whole, operation is on a greater scale than that at open-pit copper mines, but the average production of the many iron mines is much less. No iron mine handles by a large tonnage, as much material as the benches at Bingham, Utah, and few of the iron mines handle as much as the other copper mines. However, the removal of up to 21,000,000 yards of capping and 5,000,000 tons of iron ore, in a season of eight months, with 300 to 400 power shovels in operation, and standard transportation systems, is a great feat.

Well or churn drills are used in prospecting and in blasting at stripping operations. The type to be used, depends upon the character of the overburden or ore, the method of mining, and the equipment available. Piston drills or hammer drills are used at the metal mines (particularly for hard rock and bench work), and also at anthracite pits.

Blasting is necessary at all but pebble phosphate mines. Where well-drill holes have been put down, it is necessary to chamber or spring the holes, one, two, or three times, occasionally more than that. Holes are sprung, by shooting a relatively small charge of, say, 40 per cent low-freezing dynamite at the bottom, where a chamber large enough for the charge required to loosen the ground is formed. At each succeeding springing, the quantity of explosive is increased.

For actual blasting black powder is generally used at coal mines, and at copper and iron mines, both black powder and dynamite of various strengths are used. Fuse, detonators, or electric detonators, with blasting machines, are used to set off the charge. In general, air-drill holes are loaded with stick explosives, tamped, and stemmed with various materials. Bulk explosives are sometimes used, but require rather more attention in loading.

The use of liquid oxygen explosive, for shooting overburden, is increasing, particularly at coal mines. The Bureau of Mines has information of its use at five large strip coal mines. At one property in Indiana the physical and financial results were so satisfactory that the oxygen plant was doubled. Black powder was formerly used. At another mine liquid oxygen replaced dynamite. At a large open-pit copper mine in Chile owned by American capital liquid oxygen is now breaking more than 1,000,000 tons a year. The size of the oxygen plant was recently tripled. It appears to be adapted to open-pit work and its use in such projects will expand.

Great advances have been made in the design, and construction, of shovels. Stripping shovels are made in sizes ranging from 3 to 15-yard capacity. Loading shovels range from 3/4 to 3 1/4-yard capacity. There are 800 to 900 shovels of all types working at strip mines. Naturally most of these are steam driven, but the trend to the use of electric shovels, and to electrification of steam shovels is decidedly upward.

Open-pit mining is largely a problem of transportation of stripped overburden, and mined minerals. This is more complex at copper and iron mines because of the bench system of mining. In nearly every instance steam locomotives are employed, and certain types have become more or less popular, particularly at coal mines. But, as with the shovels, electric locomotives are finding a place, especially at copper and iron mines.

Strip or open-pit mining is adapted to minerals of low market value. For instance, anthracite averages $5.60 in value a short ton and bituminous coal $2.20; copper, $2.80 to $4.40 a long ton; iron. $4.55 a long ton; bauxite, $6.15 a short ton; and pebble phosphate, $3 a long ton. These same minerals, except pebble phosphate, are also mined by underground methods, sometimes in the same districts, and sell on the same market, yet naturally production costs are higher. Most of the coal and ores now being mined by open-pit methods could not, however, be recovered by underground methods, because of the shallow overburden, and contingent expense and hazard.

Detailed information in regard to the machinery and methods employed in mining by the stripping method in various fields of the United States is given in Bureau of Mines Bulletin 298, “Methods, Costs, and Safety in Stripping and Mining Coal, Copper Ore, Iron Ore, Bauxite, and Pebble Phosphate,” copies of which may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C., at a price of 70 cents.

rehab · NEW ORE IN OLD MINES TMJ 4 30 1935

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rehab · TOOLS OF THE MINE GEOLOGIST WORD POST TMJ 5 15 1939

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rehab · UP TO DATE MTHODS OF MINING TMJ 12 30 1930

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rehab · WHERE ORE COMES FROM TMJ 12 15 1930

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rehab · TIN DEPOSITS WORD POST TMJ 1 15 1940

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rehab · PROPSECTORS' PROBLEMS TMJ 9 30 1929

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rehab · FISSURES IN ORE DEPOSITION TMJ MARCH 1931

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rehab · FURTHER THOUGHTS ON ORE DEPOSITION TMJ 2 15 1931

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rehab · MORE THOUGHTS ON ORE DEPOSITION TMJ 3 15 1933

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rehab · TREATMENT OF OXIDIZED COPPER ORES TMJ 1 15 1930

for JANUARY 15, 1930

Treatment of Oxidized Copper Ores

By F. L. SWEENEY, Mining Engineer, Phoenix, Arizona

The old bug-bear of many miners, that oxidized copper ores could only be treated at a profit when rich enough to stand treatment by direct smelting, has been overcome. *

The purpose of this paper, is to point out that the treatment of oxidized copper ores has been proven to be a commercial success at many plants, in different sections of the world. Also, that the treatment need not be carried on in large plants, to be a commercial success, but rather that where conditions are right, comparatively small plants can be made to pay dividends when treating oxidized ores of copper.

I find it too often the opinion that plants for the treatment of oxidized copper ores cost far in excess, per ton daily capacity, of what flotation plants cost. This is not true. I will attempt to roughly give the history of oxidized copper ore treatment in modern times. Also, to show what may be expected in the way of recoveries, and costs, on such an ore. The fact should be emphasized that the treatment of each ore of this type must be carefully studied, and careful test work be carried on under the conditions as they prevail at the particular property.

The methods of oxidized copper ore treatment, that have been proven to be a commercial success, may be classified as follows:
A. Acid Leaching.
B. Alkali Leaching.
C. Heap Leaching, including Leaching in Place.
D. Flotation.

All of the above methods have been successfully used on a commercial scale, a few examples of which are as follows:
Acid Leaching: Ajo, Inspiration, Chile, Andes, etc.
Alkali Leaching: Calumet & Hecla, and Kennecott.
Heap Leaching: United Verde, Utah Copper, Copper Queen, etc.
Leaching in Place: Ohio Copper, Cananea, etc.
Flotation (in combination with sulfide flotation) : Magma, Ajo, etc.
Flotation: Carbonate copper only, Kennecott.

Acid Leaching
Many plants were built earlier, but it remained for the New Cornelia Copper Company plant at Ajo, Arizona, to bring modern leaching to the attention of the public, in a large way. This plant has been in operation since the early war period, and has made a mine, whereas without such a plant, Ajo would still be a desert. At Ajo, the ore is quite hard, and so no “fines” problem came up there. Briefly, and with no attempt to go into the many chemical and mechanical details of the process, the ore at Ajo is first crushed to around ¾-inch in size and bedded in large concrete, lead-lined leaching tanks. Acid-copper solutions are added to dissolve the oxide copper, after which the rich copper-bearing solutions are removed, and lower grade wash solutions applied to the ore, with the result that a high recovery of the copper content of the ore is had. The rich solutions are then precipitated either electrolytically or on iron; most of the copper being produced as electrolytic copper, and only a small portion as cement copper, the latter to correct the solutions, which become fouled during the process from other constituents of the gangue minerals that are also soluble in the acid solutions used in leaching.

Since the success of the Ajo plant, many others have been started. Particular mention should be made of the Inspiration plant, which has also been a great commercial success. At this plant, the ore contains a varying percentage of sulfide copper as well as the oxide copper. Sulfuric acid is also used here to dissolve the oxide copper minerals, with the addition of ferric sulphate and heat, in order to get a commercial extraction of the sulfide copper contained in the ore. Here, fines proved to be a problem, and with the result that at this plant they are now first classifying the ore in Dorr classifiers, and storing the slimes portion for later treatment, in a slimes acid-proof plant. The general effect of this change being that the time of leaching is shortened, the recovery of both types of copper is raised, and better costs are obtained. The same methods of precipitation are here used, as at Ajo.

The two most important points to be determined in regard to an ore, in order to see if it is amenable to the acid-leaching process, is the time needed to get a commercial extraction, and the amount of acid consumed per pound of copper produced. The time will greatly depend on the hardness of the ore, and the manner in which the copper is found in this ore. The acid consumption will depend on not only the grade of the ore and its copper content, but also on the gangue minerals present, that are also attacked by the acid solutions. If fines cause too much clogging of the leaching tank charges, then, they should first be removed, and leached separately, from the coarser portion of the ore.

Zonia Copper Mine
As the spirit of this meeting is the development of new properties, a short discussion on the test work at the Zonia plant, about 30 miles south of Prescott, should be in order. Here the ore is soft, with much kaolin being present as filling in the orebody. Hence, it is not possible to leach all of the ore at one time. After many test plant runs, this point was definitely determined, and classification of the raw ore in acid solutions was tried. The result has been that better extractions were made in the 15-ton daily capacity leaching plant, in slightly over three days, than could otherwise be made in 10 days, when all was leached in one tank.

Extractions were well over 93 percent of the copper content of the ore, practically all of the copper being in the form of malachite. By the removal of but 12 percent of the ore as fines, the ore treatment became commercial. The slimes portion is to be treated by agitation in Dorr acid-proof classifiers and then the ore washed in counter-current Dorr acid-proof thickeners. The slimes extraction is made in but a few minutes’ contact with the solutions, most of it taking place in the
classifier. This is the type of slimes treatment plant constructed at Inspiration, also.

There is nothing new in this slimes treatment as to the equipment used, it simply being a new application in a commercial way, of an old and well-known process. Iron precipitation was adopted for the Zonia plant due to several causes, chief among which are the size of the plant to be built (600 tons daily capacity), and the fact that about 30 per cent of the solutions would have to be precipitated on iron, for removal of the impurities dissolved from the ore. Electrolytic precipitation applied to 20,000 pounds of copper [ore] daily, in such a plant, is hardly commercially feasible. As it is expected to later further expand this plant, it is thought that the tonnage will warrant an electrolytic installation.

The cost of a leaching plant of 500 tons daily capacity, together with a crushing plant of like capacity (crushing, however, to be done in eight hours), and the iron precipitation plant, is far less [expensive] than might be expected. It is not necessary to use the more elaborate type of plant that is installed at very large mines. Instead, it has been definitely proven at Zonia, as well as over many years time at other points, that a plant can be built for around $500 per ton of daily capacity, and for sums slightly higher than smaller plants. This may seem a low figure, but detailed plant design in Arizona warrants the use of this figure here.
The operating costs of such a plant will, of course, depend on the grade of the ore, and acid consumption, as well as on local conditions. However, it may be stated that on an ore averaging, 1.75 percent oxide copper, [using] an acid consumption of 2.0 pounds of 100 percent acid, per pound of copper extracted, that the total operating costs to include crushing, leaching, repairs, precipitation, acid, iron, and marketing of the copper in the cement copper produced, will amount to about $0.085 per pound of copper.

Alkali Leaching
The only plants operating in America, are those at Calumet and Hecla, and Kennecott. At both of these plants, ammonia or its compounds, are used to dissolve the copper. Due to the heavy acid-consuming constituents of the ores at these two plants, it would not be practical to use acid-leaching methods.

Briefly, the process consists of crushing, as in acid leaching, and then leaching by means of ammonia-copper-carbon dioxide solutions. The ammonia in the rich solutions, is then recovered for use over again, by the evaporation or distilling of the rich solutions. The ammonia is recovered in condensers, and the copper comes out as black copper oxide, a finely divided powder.
The copper precipitates, which average over 75 percent copper, are shipped to a smelter. Washing is done with steam. All the apparatus used must be gas tight, which adds to the cost of the plant.

However, this is somewhat compensated for, as against acid-leaching plant costs, due to the fact that iron and steel can be used in place of the more expensive acid-resisting equipment of the acid-leaching plants. As a comparison with acid-leaching plants, a 500-ton ammonia leaching plant can be erected in the southwest, for around $600 per ton of daily capacity. Very little ammonia is lost. At Kennecott, for example, with a 1 percent head, the total ammonia loss is less than 0.50 pounds of NH, per ton of ore treated. The costs where steam has to be provided, and not as a by-product, will be about $0.07 per pound of copper, with no crushing or marketing costs included.

This process has made these ores, [profitable]. In the southwest, there are many points where this process can be commercially applied, if and when the grade and amount of ore warrants it.

Heap Leaching
This is probably the oldest form of leaching, it having been applied hundreds of years ago in Europe. Leaching in place has also been a commercial success at several American plants. In both of these methods the proper conditions must first be had, to make the process a commercial one. The ore must be at least partly altered and, although some sulfides can be treated commercially in this way, many others cannot. The heap and mine leaching plants have made it possible to make a profit out of many rock heaps, and old mines, that just a few years ago were considered as worthless. Utah Copper, for example, expects to recover the major portion of one billion pounds of copper from its waste dumps.

It must, however, be understood that heap and mine leaching are not fool proof methods; here again success will generally depend on proper testing and expert supervision. In late years, these plants have made rapid strides in raising the grade of the cement copper produced as well as in lowering the iron consumption. For example, at Ohio Copper, near Salt Lake City, they are making precipitates that run around 90 percent copper content, and use but 1.2 pounds of iron per pound of copper.

Flotation
Many plants are now treating mixed sulfide and oxide copper ores by flotation. For example, at Ajo, good commercial extractions are now being made on ores that have a large oxide copper content. As yet, it has not been possible to recover as large percentages of the oxide copper by flotation methods, as is usually the case when treating sulfide ores by this process. It might be said as a generalization, that so far where the predominating percentage of the copper is in the sulfide form, the ore can best be treated by flotation, but where most of it is oxide, some such process as now in use at the Inspiration leaching plant, will best fit the ore, assuming that the sulfide copper mineral is one that can be leached.

Straight flotation of oxide copper ores has not as yet been widely practiced, and little reliable data is at hand. The only commercial plant I know of is that at Kennecott, which treats a high-grade copper slime with very fair recoveries, and a good grade of concentrates. All oxide copper flotation is based on the oxide copper mineral being first given an artificial sulfide coating, and then being floated. Many flotation reagents are used; the oldest and best known is sodium sulfide.

Without doubt great advances will be made in the next few years in the art of oxide copper flotation, the development of new and better reagents being the logical step forward. On the whole, it may be said that oxide copper flotation is indeed young, and that only careful testing of any particular ore will tell if such a process can be used.

Conclusion
I have attempted to briefly point out that there are, at present, commercial applications of all the methods I have mentioned, for the treatment of oxidized ores of copper. Any metallurgist who has had proper leaching and flotation experience, can definitely determine the results and costs that can be obtained on any particular ore, by any of these methods.

Thus, the ore reserves of the world have again been added to, by the advance of the art of metallurgy, and the old bug-bear of many miners, that oxidized copper ores could only be treated at a profit when they were rich enough to stand treatment by direct smelting, has been overcome.

* Paper presented at Mining Revival, Prescott, Arizona, held by Yavapai Chamber of Commerce.

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rehab · NEW STAINLESS STEEL FORMULA TMJ 1 30 1930

for JANUARY 30, 1930

News from the Manufacturers
Recording the mechanical and metallurgical progress being made for the mining industry by equipment and supply manufacturers

Stainless Steel Alloy—

The problem of in-accessible, and exposed metal parts of buildings, has been solved by the development of a new stainless steel alloy which is now entering quantity production. This is announced by F. J. Griffiths, chairman of the Central Alloy Steel Corporation of Massilon, Ohio, and designated head of the research company of the Republic Steel Corporation, the new $850,000,000 midwest steel merger of which Central Alloy is a part.

This new alloy, known as Nirosta Steel, was discovered in the Krupp laboratories of Germany. It is being produced and developed, for mass production, under license from Krupp, by Central Alloy, and a few other American companies.

The laboratory tests have shown that the new alloy is resistant to air, water, and acids at high temperatures and pressures. The stainless quality is integral, and not merely a surfacing. Therefore, wear will not affect it. It can be made with a dull finish, which will not corrode, and will last as long as the buildings, requiring no further attention, it is stated. Substantial economies are immediately apparent when used for cornices, window frames and other places where painting and preservation of the surface now entail a considerable amount of expense.
In addition to the building industry, an important market for the alloy is in the automobile industry, where it can be used for radiator shells, and other bright parts of motor ears.

rehab · AZ MINING TO CONVERT TO NATURAL GAS TMJ 6 15 1930

THE MINING JOURNAL

ARIZONA COMPANIES SIGN CONTRACTS FOR NATURAL GAS

P. G. Beckett, general manager of Phelps Dodge Corporation, has announced the signing of a long-term contract with the Western Gas Company of El Paso, Texas, for the piping of natural gas to the Phelps Dodge mines and smelters, at Douglas, Bisbee, Clifton, and Morenci, Arizona. The contract will cover the company’s fuel requirements for a period exceeding 10 years.

Engineering work on the pipeline is now under way, but a definite announcement concerning completion of the line has not yet been made. The gas is to be piped into Arizona, from the Lea County, New Mexico, fields. It is reported that Calumet & Arizona Mining Company of Warren, Arizona, has also signed a contract with the same interests.

Natural gas is also to be made available for domestic and industrial use, in Bisbee and Douglas, according to an announcement of W. C. Hornberger, vice-president and general manager of the Arizona Edison Company, with offices in Phoenix, which company has contracted with the Western Gas Company, for distribution of natural gas to these districts.

rehab · FLOOD ROCK BLAST, LONG ISLAND, NY 6 30 1930

DESCRIPTION OF A RECORD BLAST OF FORTY-FIVE YEARS AGO

(By Albert Root, Vanadium, New Mexico)

In these days of great blasts and the breaking of immense masses of rock, about which we hear so much from time to time in the technical publications, it will be of interest to recall a great blast of 45 years ago; a blast that in many respects was epochal, and can well be compared with some of the very greatest of modern blasts. This event was in 1885, and was the occasion of the blowing up of Flood Rock, Long Island.

The details are thus: Including the galleries, from which 80,000 cubic yards were mined, and 275,000 cubic yards were blown up, there was something like three-quarters of a million tons of material handled, in addition to about the same amount of water, which was also blown high into the air. The rock thickness overhead, on which rested a varying depth of sea water, was from 10 to 24 feet high.

Four miles of galleries were first driven from a shaft, which descended to a depth of 64 feet below the sea level; 464 supporting pillars were left, having each a cross section of 15 feet by 15 feet. The blasting drill holes, 18,286 in number, were nine feet deep and three inches wide.

For blasting purposes, 110 tons of Rackarock were used. This was the last word in explosives of that day, being widely heralded as a super-explosive. In any event, it was far superior to black powder, as it could be set off by detonation.

The big charge was set off by electricity, also something quite novel for that time. A rock mass, nine acres in area, together with the superimposed water, was seen to rise a hundred feet into the air. It was all a success and the rock was thoroughly pulverized.

In reviewing some of the old press accounts of that day, it is interesting to note the attitude of the public, as expressed through the newspapers of that region, as the day approached for the experiment; to note the general uninformed status of the layman concerning physical laws, the fear, superstitions, and even religious prejudice, to which a like reaction in our present generation would seem most incongruous and out of place.

The old accounts indicate that many people were fearful that the explosion would result in a world catastrophe—that perhaps the world would split open, or at least would open up a fissure which would permit the molten interior to spew forth and in a fiery deluge, extirpating a large section of mankind from the abode of the living; to heat and boil the sea, destroying all life therein and the ships that sailed thereon.

Others, of a pious complex, protested that this thing was impious and contrary to God’s will and design. Some even attempted through the courts to stop the undertaking by injunction. Certain imbecile preachers shouted to their moronic congregations, that certainly such an unnatural cataclysmic blast would actually break through the rock arch which lies over purgatory, and thus, amidst an effluvium of a Satan, himself, with all his hosts of fallen angels, would once more be at large to stalk over the world, leaving a wake of woe, amidst the sons of men.

Many were truly apprehensive and moved inland from the surrounding cities to a safer and more distant place; others, of a more practical trend of mind, gathered near boats, prepared with scoop nets to gather a finny harvest. The old accounts say these were not disappointed.

Besides these, a treat crowd of interested spectators gathered on the heights to see the unprecedented event.

It was a solemn moment for the little group of engineers who gathered behind a log buttress to draw the switch, which would create an explosion, and consummate an engineering achievement on a scale never before attempted in the annals of their profession. It was not for them, a moment of levity. Their very professional reputations were at stake.

However, all went off well, and entirely according to their expectations. The earth did not vomit forth its molten inwards; neither did Lucifer (Lucifer, Son of the Morning) levitate his loathsome form to harry forth and blight the fair lands of Mother Earth. In this connection, however, it must be said that there were some, perhaps of an imaginative complex, who actually claimed to have seen the cadaverous visage of the Prince of Darkness, amidst the billowing clouds of yellow Rackarock fumes, and reports gave it that one man made an affidavit to that effect.

In another day and age, such a person would have seen Poseidon, himself, driving through the scud and foaming wrack of tumbling waters on his hoppocampus-drawn chariot, and with his attendant Nereids; the vision of rampant, spume-flecked steeds champing amidst the weltering waves, would have been very real to such a type, for such do the fancies of men conveniently conform their mental aberrations to the orthodox tradition of the age in which they have their being.

rehab · MOLYBDENUM PRODUCTION UPPED IN 1929 TMJ 6 30 1930

MOLYBDENUM PRODUCTION INCREASED AGAIN IN 1929

Four companies produced molybdenum ore in the United States during 1929, the Climax Molybdenum Co., at Climax, Colorado; the Molybdenum Corporation of America, at Sulphur Gulch, near Questa, New Mexico; the Southern Copper Mining Co., at Helvetia, Arizona; and the Minerals & Metals Corp., near Sahaurita, Arizona; according to data collected by the United States Bureau of Mines.

In 1929, a total of 419,400 short tons of ore was milled, yielding 3,854 tons of concentrates, carrying from 75.40 to 88.38 percent molybdenum sulphide. In addition, a small tonnage of ore carrying 16 percent of molybdenum sulphide, was produced, and sold without milling. The metallic molybdenum content of the concentrates and ore so produced, was 4,020,607 pounds, an increase of 11 percent over 1928. The shipments of concentrates and ore from the mines, contained an equivalent of 8,904,648 pounds of elemental molybdenum valued, more or less arbitrarily, at $2,259,000 at the mines.

rehab · NORTHWESTERN PORPHYRY COPPER DEPOSITS TMJ 1 15 1930

Northwestern Porphyry Copper Prospects
By ROBERT N. BELL, Boise, Idaho.
The second of a series of articles covering the principal porphyry copper prospects in the northwestern United States.
Particular mention is made of the Idaho Copper Company.

The most productive copper-gold ore deposit to date in the Snake River Province, is the Iron Dike Mine, which carries some remarkably interesting and controversial features from a geologic standpoint. The following quotation from the 22nd Annual Report of the U. S. Geological Survey, by Waldemar Lindgren, made thirty years ago, covering this property in its early stages of adit development, is of keen interest in its general application to other outcrop condition of the province.

“The croppings are large masses of black and brown stained rocks, one knoll rising 75 feet above the general slope, and measuring 100 feet across. It is said that the croppings can be traced for some distance in a west-northwesterly direction. At any rate, few walls or fissures can be seen; one near the mouth of the highest tunnel, strikes north 55 degrees West, and dips 60 degrees South. The maximum width of the croppings is probably 200 or 250 feet. On the rusty surface of the croppings, scarcely any copper stain indicates the heavy body of chalcopyrite immediately underlying it. Holes a foot or two deep, show somewhat decomposed pyrite, but very little chalcopyrite, the latter appearing only a little farther below the surface.

The upper tunnel, for the first 100 feet, is in heavy ore of mixed chalcopyrite and pyrite; then follows 80 feet of poorer ore. A sharp contact here separates the chloritic greenstone from the dark-brown meta-andesite. Crosscuts extending 25 feet each way in the best part of the ore, show a width of four feet of solid sulphides which may average 15 to 20 per cent in copper.

The largest part of the tunnel is, of course, in poorer ore, consisting of disseminated pyrite and chalcopyrite in chloritic greenstone. There are also abundant quartz seams, veinlets and nodules, which contain chalcopyrite, and often a regular silicification of the rock may be noted. Zinc blende or galena rarely occurs, and a little antimony is contained in the best ore. The ore contains about $2 in gold, and 6 to 80 ounces silver, per ton. These amounts are apparently independent of the percentage of copper. The intermediate tunnel, 150 feet long, with a crosscut 125 feet toward the west, also shows a heavy body of sulphides. If the lowest crosscut, now being driven, exposes similar bodies of ore the deposit will be of considerable value.”

The original owners of this property seriously underestimated its remote situation, and transportation difficulties, before the branch railway was constructed. They developed the mine to the 400-foot level by crosscut adits and drifts on the vein, tying up several hundred thousand dollars in the enterprise, which failed to pay, in such a remote situation. The subsequent history of the property is of keenest interest.

In 1914, the writer called this property to the attention of Thayer Lindsey, now so prominent in Canadian mining progress, who obtained a long lease and option to purchase the property, and is said to have paid for it out of royalties on subsequent ore shipments. As the story goes, Mr. Lindsey and his associates invested just $5,000 in re-timbering and shaping up the old development for production. He took hold of the enterprise late in 1914, when copper metal prices were all shot to pieces by the U boat activities of the war, but he apparently had an uncanny foresight as to their early recovery. According to published records of the Oregon Mining Bureau, from December, 1914, to December, 1915, he shipped 480 cars of crude ore; subsequently built an up-to-date 100-ton capacity flotation mill, and established an elaborate modern camp, including a large boarding house, bunk houses and 80 bungalow-type cottages for married men.

The property was connected with the Idaho Power Company’s plant at Copperfield, four miles farther south on the river, where an abundant supply of electric current was made available for operating the machinery.

A shaft was started from the 400-foot adit level; in fact a winze was already down 100 feet at this point, in blank but highly oxidized gangue, which Mr. Lindsey recognized was not the bottom of the deposit. At a short distance below this winze bottom he ran into the most noted orebody of the property, which proved to be 150 feet in width, length and depth —an apparently isolated block of ore— that was richly and fairly uniformly sprinkled with pyrite and chalcopyrite in a very hard, siliceous gangue, and is said to have given average mill feed values of 5 percent copper, and $8.00 gold, per ton, with a production of 160,000 tons. A new shaft was sunk, near the portal of the lower tunnel, 440 feet deep through which this big ore body, and other ore bodies, were extracted.

The enterprise was actively operated for five years, until shortly after the close of the war, when it was shut down, and remained dormant for several years, and was subsequently sold in 1925 for $100,000 after a production that is said to aggregate $5,000,000 in gross value of crude ore and concentrate shipments, and $3,500,000 net smelter returns. The nature of this deposit and its development, subsequent to Lindgren’s studies, has proven quite a controversial problem with the geologists who examined it.

In 1926, the property fell into the hands of the Idaho Copper Company, and the three-compartment shaft was extended 200 feet deeper and below the level of the river, which is only 2,000 feet distant, some drifting done, and a large footage of diamond-drill work accomplished, particularly from the 740 level. This drilling campaign is said to have given some very interesting core results, indicating large bodies of ore with values ranging from 1 to 3 per cent copper, with the usual associated value in gold. Contrary to the shallow development promise, gold is the predominant associated value with the copper, and the silver unimportant, rarely exceeding a few ounces in the concentrates.

In its present development, the deposit looks like a tabular ore shoot, a thousand feet long, distributed by thrust fault movement, and broken into blocks or so-called boulders of ore through the later injection of flat dipping igneous dikes of yellowish and green basic igneous rock, and a thick zone of injection breccia which carries, in its matrix, marginal disseminations of chalcopyrite in bodies of ore, from a mere pebble, to blocks containing several thousand tons. These disturbed ore bodies, including the main 700 stope, which is said to have produced 160,000 tons of ore, are scattered through a disturbed zone 800 feet wide between two normal faults. The immediate bounding formation to the north is rhyolite, and to the south, the complex of greenstone formations with thick horizons of volcanic and calcareous breecias and conglomerates.

It has been suggested by some geologists that these disturbed ore bodies are fragmental boulders formerly associated with the neck or branch of a volcano of caldera proportions, and something on the order of the Braden Mine [Chile] South America. While there is no conspicuous surface evidence of such an orifice, the suggestion is not without value, as the vast accumulation of predominantly plastic material, which constitutes the 10,000 feet of associated greenstone formations, tuffs and breccias, must have involved one or more vents of such explosive character.

There is evidence of two such vents, several miles in diameter, farther down the river near Pittsburg Landing, with telltale patches of lignite coal indicating former crater lake marginal accumulations of organic matter. Such an orifice may exist near the Iron Dike Mine, and be obscured by the basalt cap, which covers the formation for miles in three directions. In 1926, the Iron Dike Mine was taken over by the Idaho Copper Company, and actively operated for over a year with a production of $70,000 in concentrate shipping values.

During its recent operation, a ventilation raise was extended from the 740 level, on the south side of the zone in virgin ground, to the 400 surface adit level. This raise was completed just before the operation was shut down, and passed through 100 feet of ore carrying sectional assay values of 1 to 8 per cent copper with the usual associated gold values. The full sectional dimensions of this ore body are as yet unproved.

The old mill on the property was partly renovated, and in the hands of a competent operator, formerly with the Utah Copper Company. The shipping grade of the concentrates was raised from 12 per cent under some previous leasing operations, to 22 per cent with $19.00 gold and a few ounces of silver per ton.

At this stage in 1927, the enterprise, with its associated properties, the Red Ledge and the South Peacock mines, got into difficulties resulting apparently from a factional quarrel among the company’s directorate, for control, and the enterprise was put into the hands of a receiver, and has been dormant for the past two years. This receivership was terminated during October 1929, and it is currently reported that this unit of the companys’ holdings is to be turned over to a prominent Arizona leasor, and operations on its further development and equipment, commenced at an early date.

In the vicinity of the Iron Dike mine, there are numerous promising copper prospects. The ore bearing greenstone formations are obscured by the thick flows of Columbia basalt, except for a narrow belt between the lower beds of the basalt, and along this side of the river, for 50 miles to the north, where the greenstone formations are cut by several copper bearing quartz porphyry dikes up to 2,000 feet in width, in the vicinity of Rush Creek, and Pittsburg Landing; the latter a notable ferry crossing of the river, about 45 miles north of Homestead.

The Imnaha River, 60 miles north of Homestead, with its source in the granite slopes of the Wallowa Mountains, has scored a canyon through the basalt series to the underlying greenstones, which exposes numerous copper bearing ore courses, both of the fissure and zonal type. One of these fissures, situated at the confluence of the two rivers, has a tunnel about 50 feet above the water level of the two streams through which the intervening point follows a massive vein of hematite, from five to 12 feet thick, carrying 4 per cent copper in the form of disseminated chalcopyrite and bornite. Smaller veins of much higher values are found in this vicinity and they all carry a good gold ratio associated with their copper values.

The third of this series of articles on Northwestern Porphyry Copper Prospects will appear in an early issue.

wallowa ore copper pics here

rehab · UNITED VERDE EXTENSION MILL, JEROME, AZ TMJ 6 30 1930

for JUNE 30, 1930

U. V. X. FLOTATION MILL WILL HANDLE SILICIOUS ORES

Construction of the new 200-ton flotation plant, by United Verde Extension Mining Company, Jerome, Arizona, will be completed within the next two months. This will give United Verde Extension facilities for the treating of its ores high in silica content, which show no oxidation.
The smelter crushing plant will be used for coarse crushing, and four of the smelter bins have been set aside for the mill feed. The equipment that is to go into the new plant consists of a seven-foot by five-foot Marcy ball mill, and eight-foot Dorr classifier, 10-cell Fahrenwald sub-A rougher flotation machine, four-cell cleaner of the same type, 40-foot Dorr thickener, and a 10-foot by four-foot Dorr filter.

In many ways the proposed treatment of the milling ores will be unique, as compared to the usual practice. While the usual procedure calls for a high ratio of concentration, in the case of the Verde Extension ores, the primary object will be the removal of one undesirable constituent, the silica, or insoluble content of the ore, while retaining the iron sulphides in addition to the copper sulphides, on account of the fluxing value of the iron. The benefit derived will be two-fold: first the mill will relieve the smelter of excess silica ore to the extent of the tonnage milled, and, second, the mill will furnish the smelter with concentrates of low silica content which can be mixed with some of the oxidized silicious ores and aid in smelting.

The mill will probably have a capacity, under favorable conditions, of 200 tons per day. The ratio of concentration by the bulk flotation of the iron sulphides will be low, giving probably 80 tons of concentrates per day. The usual mill of this capacity will average from 15 to 20 tons per day.
The total tonnage of ore to be handled by the flotation process, is estimated at 400,000 tons of 5% percent ore- The company feels that under the conditions prevailing, this tonnage could not be profitably handled except by flotation.

The plant was designed and construction supervised by E. L. Sweeney, consulting engineer, Phoenix, Arizona. Equipment was purchased from the Mine and Smelter Supply Company of Denver, Salt Lake City. and El Paso.

rehab · DR. TAYLOR; UNIVERSITY OF UTAH TMJ 8 30 1930

DR. TAYLOR ASSISTING WITH X-RAY WORK AT UTAH UNIVERSITY

Dr. Nelson W. Taylor, of the Department of Chemistry, of the University of Minnesota, who, during the past year, has been studying in Germany on a Guggenheim fellowship, is spending the months of August and September, at the University of Utah. He will act as consultant to the Department of Mining and Metallurgical Research, on the X-ray work, which is being carried on in that department, in connection with the study of the physics of minerals, in cooperation with the United States Bureau of Mines.

Geochemistry, and application of modern physical-chemical methods, to mineralogical problems, interested Dr. Taylor for many years. While in Germany, he did X-ray work in the laboratory of Professor V. M. Goldschmidt, whose work in the last seven years has shed much light on the structure of crystals, and on the geochemical distribution of the elements.

Dr. Taylor expects to return to the University of Minnesota in time to resume his work in the Department of Chemistry, at the beginning of the Autumn quarter.

rehab · MICROSCOPIC INVESTIGATIONS OF COMPLEX ORES 11 15 1930

for NOVEMBER 15, 1930

MICROSCOPIC INVESTIGATIONS OF COMPLEX ORES OF VALUE

An almost unlimited application of the microscope in the field of ore-dressing problems, is indicated as a result of microscopic investigations conducted at the Intermountain Experiment Station of the Bureau of Mines, in co-operation with the University of Utah, Salt Lake City.

During the progress of this work, the microscope has been applied as a fact-finding instrument to determine the mineralogical, and other physical characteristics, of numerous complex sulphide, and oxide ores.

Since the amenability of these ores to flotation or other treatment depends primarily upon the knowledge on the part of the operators of their physical structure, the data supplied by the microscope are invaluable.

The application of the microscope to ore-dressing problems, in general, is not restricted to the study of ores, but is equally valuable as a fact finder in the study of concentrates, tailings, residues from leaching operations, mattes, and slags, in fact, practically every metallurgical product whose physical condition has a bearing on the cost, or process involved, in producing it.

Microscopic studies conducted at the Intermountain Experiment Station have shown that tailing losses in treating complex ores, may be due to a variety of causes such as: Failure to grind sufficiently fine to liberate the valuable minerals, tarnished or oxidized films on the mineral surfaces, contamination of the surfaces of mineral particles with clay, iron oxide, and the slime products of rock decomposition, and the presence of rare, or uncommon minerals, whose existence was not suspected, and no special provision made for their recovery.

Studies made of residues resulting from the leaching of low-grade copper ore, have shown that the extent of fracturing in the ore, and the relation of the mineral grains to the fractures, are important factors in the time required for leaching. Since solutions penetrate rapidly through these channels, and thus assist in the permeation of the rock, contiguous mineral particles are attacked more readily, and isolated, or disseminated particles require a much longer time of treatment.

Mill operators and persons engaged in testing work or the treatment of ores cannot afford to neglect the microscope, since it has proven of constant value in the solution of metallurgical problems.

rehab · RADIORE GEOPHYSICAL PROSPECTING TMJ 12 15 1930

Results of Some Recent Geophysical Tests

By L. H. HENDERSON, and V. P. PENTEGOFF, Geological Engineers, and Field Engineers
for The Radiore Company, Los Angeles.

A number of interesting problems have been solved for mining companies by use of this modern prospecting method.

The art of geophysical prospecting has developed very rapidly in the past few years. The interest in this field is increasing tremendously, as indicated by the number of technical colleges now giving a course of study in geophysics, to supply the growing demand by the larger oil, and mining companies, for geophysicists.

In this scientific field, the Radiore Company is one of the pioneers in North America. Six years were spent in research by the organizers of this company before any work of a commercial nature was done. The Radiore high-frequency inductive process of prospecting, was finally developed to a stage where reliability of results was assured, and in 1925, the Radiore Company was organized. Since that date, the company has been successful in solving structural problems, and in locating sulphide mineralization under varied conditions, throughout the United States, Canada, and Mexico.

An intensive research program has been maintained in the field and in the laboratories, at all times, by a highly trained personnel. This insures the process the latest improvements in equipment and technique -all of which makes for efficiency and dependability.

As the object of this paper is to publish some actual results obtained by a Radiore geophysical survey, the procedure and methods used will be discussed but briefly.

The Radiore high-frequency inductive method is used as a rapid means, in a reconnaissance survey of an area, to localize the mineralization. While this preliminary survey is in progress, a geological study is made of the area under consideration, by a geologist, independently employed, or attached to the crew. The results of the inductive survey are then interpreted in the light of the geological observations. After proper correlation of the complete data, the electrical indications which may warrant further consideration are studied in detail by a supplementary method.

In the supplementary surveys, one or more of the following methods are employed, depending upon the detail desired: various potential distribution methods, the magnetic method, and in some instances, the gravimetric method is used. These supplementary studies serve the two-fold purpose of checking the preliminary work, and giving more detail as to the sub-surface conditions.

An abundance of literature has been published in the past on geophysical methods of prospecting and the results of experimental work. There has been very little published, however, on the actual results of geophysical work of a commercial nature. A number of problems solved recently by The Radiore Company are given below. Most of these are typical problems and were picked with regard to locality to give some idea as to the diversity of conditions encountered.

Silver Monument Mine
This property is located on the eastern flank of the Black Range, Sierra County, New Mexico.
The ore found in this area occurs in veins in late-Cretaceous, or early Tertiary
andesites. These veins constitute shear zones, along which silver-bearing copper sulphides—chiefly bornite—have been deposited. Previous to the geophysical survey, one oreshoot had been developed in a large east-west vein. The object of the survey was to locate any additional oreshoots which might occur in the unexplored extension of this vein.

The geo-electrical survey was conducted by a potential distribution method, along the surface outcrop of the vein, for 1,500 feet. Four “highly conductive zones,” which were attributed to sulphide concentrations, were located with respect to depth and outlined. These “highly conductive zones” proved to be the upper limit of oreshoots which rake 60 degrees to the east.
Since the completion of the survey, three of the four indicated zones of sulphide concentration have already been developed by the operators, and have proven to be ore bodies—one of which carries 2,000 ounces of silver per ton.

The following is taken from a letter of F. W. Cook, Manager of the Silver Monument Mine, for the Velie Royalty Company, El Paso, Texas:

“The geophysical survey at the Silver Monument Mines has proven very satisfactory. As far as we have carried our developments, we have found the ore exactly where indicated. We are very well satisfied so far.”
(See Plate No. I)

Spruce Standard Mine
The Spruce Standard mine is located on the west slope of Spruce Mountain, Elko County, Nevada.

The surface exposures on this property are mainly blue-gray Mississippian limestone, interbedded with shales and quartzites. These sediments have been intruded by granite-porphyry, and diorite porphyry dikes.

The ore deposits in this area, with a few exceptions, are replacements in limestone, closely associated with fractures and faults, and with the intrusive igneous rocks. The ore minerals are argentiferous galena, chalcopyrite, and some chalcocite.
Previous to the geo-electrical survey, ore had been developed along a mineralized fracture at a depth of 265 feet. The purpose of the survey was to locate any additional mineralized fissures, which might be present on the property. The high frequency induction method, and a potential distribution method were used in this work.

Sixty acres were covered by the survey in five days. Six electrical indications were located, which were attributed to mineralized fissures. In addition, the greatest sulphide concentration on the property was found to be in a badly brecciated area known as a “blow out.” This area was recommended to be explored immediately.

A drift was started along electrical indication No. 1, which proved to be a mineralized fissure carrying copper and lead ore. The drift was continued some 700 feet to the blow out, where a zone 150 feet in width, carrying high percentages of iron sulphide was found, at the periphery of which, a five-foot band of lead and zinc ore occurs—thus checking the electrical indications perfectly.
(See Plate No. 2)
Silver Plume Mine

The Silver Plume Mine, of the Minaret Consolidated Mines Company, is located in a country of gently rolling hills, 27 miles south of the town of Cananea, Sonora, Mexico.

The entire area is covered by andesite and rhyolite agglomerates and flows, with the exception of several small bodies of undifferentiated intruded rocks, (probably syenite), found in the eastern and southeastern part of the property. Mineralization here is entirely confined to the numerous quartz and barite fissure veins cutting through the flow. Principal ore minerals found are silver bearing galena, tetrahedrite, chalcopyrite, and some gold.

Previous to the geophysical survey, the Spar Vein of the property, was partially developed, and a considerable amount of ore was shipped. A number of other veins were prospected, and in several cases, the presence of a commercial ore was established. In order to find the extension of these known ore bodies, and especially to locate new ones, the property was covered by a geo-electrical survey. In this survey, the high-frequency induction method was used almost exclusively, with an exception where more detail was desired, and a resistivity method was employed.

In this survey, an area of 350 acres was covered in 18 days. Nineteen electrical indications were located, four of which followed known ore bodies, and the remainder were in unexplored territory. Up to the present time, five of these indications have been explored by the operators,
and in every instance, a perfect check was obtained.

The following is taken from a letter from C. C. Randall, Manager of the Minaret Mines Consolidated Company, in which he expresses his opinion of this survey:

“The survey showed a number of conductors on our Silver Plume Property, in Mexico, and to date, we have proven their finding in five different places. So far the results have been all and more than was predicted by them.

“I feel that the Radiore survey, is only another aid that has been placed at our command to minimize the risk of legitimate mining, and so far have no reason to doubt their finding in any particular.”
(See Plate No. 3)

Chino Mine

Very recently the Radiore Company conducted surveys near Silver City, New Mexico, for the Nevada Consolidated Copper Company, and the Illinois Zinc Company. While in this area, a short experimental survey was conducted on the Santa Rita ore body, to determine the adaptability of a geo-electrical method to the prospecting of large low-grade disseminated deposits. This work was permitted by the courtesy of John M. Sully, Manager of the Chino Mine, for the Nevada Consolidated Copper Company.

The Santa Rita ore body occurs at the periphery of a large granodiorite porphyry stock, in a badly fractured quartz diorite porphyry sill, in which intrudes upper Paleozoic and Mesozoic sediments. The ore mineral, chalcocite, occurs as a replacement of pyrite, and is disseminated through the granodiorite, the quartz diorite, and to a lesser extent, through the sediments. The ore runs 0.8 percent to 2.0 percent copper.

The object of the survey was to outline the upper limit of the disseminated sulphides, which averaged (inclusive of pyrite) 4 percent total sulphide content.

The survey was conducted along two lines of churn drill holes, comprising a total of eleven holes. This survey was conducted independently, and without knowledge of the drill hole data.

Upon the completion of the survey, the electrical profile of the sulphides was submitted to the Chino Geology Department, for comparison with the profile obtained from the drill hole data. These two profiles checked very closely, and the results lead to the belief that, disseminated mineralization may be definitely outlined by certain geo-electrical methods, although the total sulphide content be as low as 2 percent.
(See Figure 1 and Figure 2)

lnglewood Oil Field

The property of the Richfield Oil Company, which was covered by a geo-electrical survey, is located in the immediate vicinity of the town of Inglewood, California.

The object of this survey was to locate the major fault zones, which are expected to occur here. The topography of the area does not reveal any definite information as to the position of these zones, with the exception of the Inglewood Fault, which is expressed on the surface by an escarpment. A potential distribution method only was used in this survey. As the result of this work, the extension of the Inglewood Fault, and three additional fault zones, were definitely located.

If details of this survey are desired, refer to L. E. Porter, Chief Geologist of the Richfield Oil Company.

Conclusions
The above surveys represent but a minor portion of the problems successfully solved during the past year. In addition to the above types, problems involving the locating of water tables, water sands, and bedrock strata have been also successfully worked out.

The past eight months have witnessed the development of new apparatus by the research department, which permits greater depth range (to depths of at least 1,500 feet), and more detailed information as to the sub-surface condition.

The rapid stride made in the development of the geo-electrical processes and equipment, definitely warrant the employment of these modern methods, as the most logical and economic step in the exploration and development of mining and oil properties.
—

PLATE 1

PLATE 2 Map of detailed electrical survey for Spruce Mountain Mining Company, Sprucemont, Nevada.

Plate 3. Details of the electrical survey of the Silver Plume property of Minaret Consolidated Mines Company, Cananea, Sonora, Mexico.

=-=-=-=

FIGURE 1 Map showing area in which electrical survey was conducted at Chino Mines, Nevada Consolidated Copper Company, Santa Rita, New Mexico.

Figure 2. Comparative profiles of results from electrical survey and drill prospecting at the Nevada Consolidated Copper Company, China Branch.

rehab · WHERE DOES ORE COME FROM TMJ 12 30 30

DECEMBER 30, 1930

Where Does the Ore Come From?

By A. R. FLETCHER, Consulting Engineer, American Metal Company.

Suggesting that the constituents of ore bodies did their traveling as gases, condensed to solutions only when they neared the surface where ore deposition occurred.

There is probably no thoughtful mining man who has not, from time to time, asked himself where ore came from. It is one of those insoluble, but recurring perplexities, that plagues a man in his reflective moments, as do the mysteries of germination, growth, death, and possible immortality. To throw your light on a back of ore, 20 or 30 feet wide, waiting to be broken, is a sweet sight, but, at the same time, to realize that you have looked for its downward continuation below, on the tenth level, and then not find it, is not so comforting. If ore bodies pinch out with depth, as we know them to do, how did the ore bodies get to the places it occupies in commercial quantities, near the surface? How could such a considerable quantity of ore-making material ascend the underlying fractures, without leaving convincing traces of its passage?

There would be small excuse for embarking on this article if geologists were inquisitive. As a matter of fact, most of them are not; instead, they are studious. Turning to the geologists for an answer as to where the ore came from, we elicit no satisfactory response. They merely obfuscate us with terms like vein-dikes, solutions, magmas, and gels. I sometimes suspect them of falling in love with the sonorous Latin and Greek terms of their profession. They seem inclined to turn a technological vocabulary into a ritual, to be pontifically intoned, rather than use the terms of that vocabulary as tools, continually to be scrutinized for defects, and re-sharpened and reshaped to cope with new experience. They have not answered satisfactorily the question propounded in this article, “Where does the ore come from?”

Geologists, for the most part, cannot answer the question. For that matter, neither can I, but I can at least attack it, and summarize, and generalize the experience gained, at the expense of much sweat, and ladder climbing, in many mines. I hope to indicate a line of attack that has been neglected. I believe I can make the mystery of the birth of ore recede one step, and that, in the last analysis, is all we ever do with the mysteries that surround us in that wonderful world—make them retreat a step at a time.

It may be well to begin the serious part of this paper by summarizing some of the things we know that are true of all mines, or of a sufficient number of them, to make the generalizations valuable:

·Mines occur in regions of igneous approach.
·Intrusions and dikes are notably numerous in the vicinity of mines.
·Rock temperatures at a given vertical distance below the surface, in the vicinity of mines, give evidence of being, or of having been, higher than those found in non-mineral regions at the same vertical distance below the surface.
·Sulphur is, or has been, present in the ores of most mines.
·The ores and gangues of veins are not like the wall rock, and it is difficult to conceive them as having been derived either from the adjacent wall rocks or from other deeper seated rocks of the region, the existence of which may have been revealed naturally by erosion, or artificially, by the perforations of the diamond drill.
·All veins were once faults.
·The mineralizer that creates an ore body, follows the course of least resistance, which is available to it from its source, to the place of deposition.
·The fractures, faults, joint planes, shear zones, and their intersections, which define
·the channels traversed by mineralizers, tend to diminish rapidly in width and number, as depth is gained.
·Movement makes mines.
·Minor movements, many times repeated during mineralization, along planes of weakness already established before the advent of the mineralizer, make great mines.
·The cataclysms associated with regional faulting and mountain building, do not produce mines. The secondary adjusting movements that inevitably follow such periods of cataclysmic activity, do produce mines, provided they occur at the right time.
·The relatively feeble adjusting movements, characteristic of a period of mineralization, and occurring repeatedly along previously defined planes of weakness, penetrate more deeply into the crust, than the original cataclysmic movements that created the planes of weakness.
·Ore deposition is a phenomenon associated with the recession of igneous and dynamic activity from a district.

I believe most mining engineers will subscribe to the soundness of the generalizations above stated. There is nothing new in them except the emphasis placed on movement, as an agency, in the formation of ore bodies. Professional geologists, with few exceptions, think of ore bodies in terms of chemistry, and are only beginning to realize the all-important role in which movement plays in the formation of an ore body.

The rest of my premise has to do with matter, and is of easy

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