The Editor:
Mining engineers will he pleased to know that our friend and colleague, Mr. Leon A. Perret is safely out in Japan, now that things are so slow in Russia, and it is interesting to discuss how to operate some of these big and rich placers to best advantage, so as to ensure regular and adequate dividends to capital, without which, we shall not get very far.
I take it that Mr. Perret would have liked to have encountered more capital (foreign or Russian) invested in mining, placer mines for preference, in Russia and Siberia, where several engineers were looking for suitable properties for that purpose. Few Russian undertakings can afford to develop their mines adequately, previous to extraction, and the need to recover the initial expense as quickly as possible. Want of capital, from which Russian placer mining is suffering, accounts for the lack of better mine development under more suitable conditions.
It is the lack of adequate prospected reserves that causes capital to be withheld. The more frequent procedure is to prospect in the winter, for the work of the coming summer. Such a hand-to-mouth policy of working in the dark [long winter nights] is unsatisfactory, and is apt to lead one accustomed to it, to make the remark be does, with reference to the Lenskoie company’s 17-ft. dredge:
“The Lenskoie company can afford to try such an experiment, but I believe there will not be many placer companies in America, to say nothing of Russia, disposed to risk such an expenditure at the start. Just think of the cost of transporting two or three dredges of that size to an isolated district in Russia.” However, Russian placer districts are exceedingly rich, once located, perhaps justifying otherwise unconventional methods of exploit.
Proper prospecting goes a long way toward removing the business from the insinuation of the word ‘experiment’, which might well be applied without such prospecting. Proper prospecting results give information that can be laid on the table, and with the other data necessary, helps to dispel ignorance of local conditions, and suggests suitable decisions to those putting up the money. After all, mining engineers the world over are good fellows, including Leon Perret, whom I know very well.
I well remember in 1912, taking up the work at Nicolo Pavda. This platinum placer ground was apparently about worked-out then. I was told that Mr. Perret had previously initiated the work with a bedrock tunnel property and many of the devices described by him produced excellent results at that time, before he left for the Schnvaloff property. After Perret left, the remaining enterprise chose not to follow his leads and plans, and the subsequent company leaders ran off course. The ground became deeper, labor a little more costly, and the known deposit was taken as nearly exhausted.
Observers had considered that the boulders, clay, bedrock timbers, and difficult digging would prove unsuitable for dredging. Briefly, investigation disclosed 26,000,000 yards of good dredging ground, averaging of 32 cents per yard at that time, and of double that value now. Conditions called for powerful heavy dredges, which were obtained, and success was assured from the outset. This illustrates the difficulty of making generalizations, for every property becomes an exception when you are about to spend money in equipping it with a view to getting maximum profits.
This particular part of the Nicolo Pavda property called for four electrically-driven elevator-dredges. One American 7 1/2-ft. electrically-driven elevator-dredge was bought, erected, and started in 1915, working profitably from the first. The power station was three miles away in the forest—the nearest place where conditions were suitable for generating power to advantage. All the near-by forest had been cut down for previous work.
Somewhat reluctantly, we installed a steam 5 1/2-ft. dredge manufactured in Russia, on easier digging ground which I had recently discovered, owing to the difficulty of getting what was wanted at that time. It was smaller and lighter than I would have selected otherwise, but we had to do the best we could. The power-plant was steam, and the boiler was good, so we got a direct comparison as far as possible under our conditions, although the work required of the steam Putiloff dredge was much easier. The American electrically-driven elevator-dredge (similar to Boyle’s dredges at Dawson) was digging regularly 3000 yards, and the Putiloff steam dredge just about half that yardage; both worked about 17 hours per day (local Russian conditions).
The point is that the power-plant of the electric dredge consumed 3 1/2 cubic sagenes [a Russian measure equal to about 0.8 cubic yards] of firewood per day, whereas the steam dredge consumed 5 1/2 cubic sagenes of similar fuel. It is incidental that the firewood cost twice as much for handling when burnt on the steam dredge, per cubic sagene, as similar fuel burned in the powerhouse of the electrically-driven dredge. At Nicolo Pavda there was no divided opinion as to whether a steam or an electric dredge should be employed, even before we started, but I must admit I did not realize that the difference would be so great. Subsequently two more dredges of American manufacture were purchased, and there is every reason to suppose that they will give satisfactory results, as the platinum is there, and we know that this kind of machine is no experiment.
Working expenses of all kinds amounted to 4 cents per yard, and amortization or redemption of capital to another 4 cents per yard, on a basis of ten years life, so that there was considerable profit on 32-cents ground; and then platinum went up. The cost of working was 12 cents per yard, or three times that of the steam dredge.
There are lots of electric-power plants at factories and works in the Ural Mountains using De Laval steam turbines and jet-condensers; these have operated three or four years without delays for power, so that Mr. Perret may feel encouraged to give impartial reference to his local conditions next time, without being prejudiced by the unforeseen difficulties encountered by the Orsk Goldfields. All credit to those men who hung on for the nine long years before realizing their aim. They stayed right with it.
The old tailing-heaps at Nicolo Favda contained no platinum worth considering, as was proved by exhaustive tests. One must certainly compliment the skilled Russian hand-washers for making a clean tailing when clay does not bother them.
Many years ago, when work was started, the shafts beside the Bodaibo River were sunk to bedrock in frozen material, but when I inspected the ground in 1916, the recent prospecting had shown that the ground to be dredged had thawed, no doubt from the effect of clearing, circulation of air, and water in the workings, and effect of the river. The surface round could be thawed if necessary, and I hope that the time will come soon when dredges will get busy at Bodaibo. There is plenty of room on other frozen ground where the other methods so eloquently advocated and so suited to conditions still existing in that far-off gold district may have full scope.
