THE STORMONT SILVER MINES, SILVER REEF, UTAH,—IV,
With Supplement.
THE BUCKEYE MILL.
The Buckeye or Pioneer mill, belonging to the Buckeye property, is situ-ated at a distance of one and a half miles by the road from the mines, its location having been selected as central to several very promising mines on the southern portion of the reefs. While this position may have been advantageous as a general custom mill, it certainly is not so for the Buck-eye property; for it now costs $1.50 per ton (which, however, might be reduced to $1 per ton) for hauling ore from the mines to the mill. On this account, and because of its small capacity and defective arrange-ments, this mill, notwithstanding its remarkable record, can not be said to have any great value to the owner of these mines.
The following details give an idea of the mill. It consists of 3 head of stamps, 750 pounds, which make from 80 to 100 drops per minute, with a fall of 5 inches.
The battery can readily crush an average of 6 to 7 tons per 24 hours to the head of stamps—say 20 tons a day. The limiting point in this, as in every other mill in the camp, is an insufficient pan capacity. The pulp from the battery runs, as is usual, through tanks where the ore is depos-ited. This is next chloridized wet in 6 pans 4' 6" diameter and 5' 8" deep, the shaft in which revolves at half the speed of the battery. The charge in chloridizing varies somewhat with the nature of the ore; but it is about 4 per cent of salt, 1 ½ lbs. blue-stone, 1¼ lbs. mercury, and 1 ½ lbs. commercial (65°) sulphuric acid ; or for slimes, 6 per cent salt, 2 lbs. blue-stone, and 1 to 1 ½ lbs. sulphuric acid. The charge remains six hours, and is then run into the amalgamators, which till recently were exclusively Freiberg barrels; now one pan has been introduced to re-place a barrel which it was found to be almost impossible to keep tight.
The amalgamation lasts six hours, and the charge is about 2500 lbs. of ore. This charge is next run off into the settlers, where it remains three hours. The motive power for the mill is furnished by an engine 12"×18" steam-cylinder, and two tubular boilers, one of which is sufficient to supply the steam required.
The loss of quicksilver in the amalgamating and retorting exceeds 1 ¼ lbs. per ton.
Previous to August, 1878, the battery ran only twelve hours per day, and the capacity of the mill was ten tons a day.
A considerable quantity, from 10 to 15 per cent, of the silver contained in the ore goes out in the slimes, which are re-worked with the ore-pulp from the battery.
The supply of water is quite sufficient for the mill.
THE STORMONT MILL.
The Stormont or Rock Cliff mill, situated on the Rio Virgin, about five miles from the mines, is unquestionably the best mill now working Silver Reef ores. It is provided throughout with new plant and machinery, manufactured by Messrs. FRASER, CHALMERS & Co., of Chicago, whose experience and acknowledged preeminence as manufacturers of this class of work are sufficient guarantee of its quality.
The mill is about 650 feet lower than the Stormont mine, and as there is little or no fall in the first mile, this elevation would have to be overcome in about three and a half or four miles—a grade which would be very inconvenient, though not impossible, in a railroad. The mill is run by means of a 48"-diameter turbine-wheel, abundantly supplied by the waters of the Rio Virgin, which are collected by a low dam across the stream one and a half miles above the mill, and conducted through an extremely well-built canal to the mill, where they have eighteen feet of head to the turbine. The mill has ten head of 650-pound stamps, which work with a fall of six inches, and make 75 to 100 drops per minute. The ore is broken in a Blake crusher (two men working twelve hours), and then falls on to the battery plat-form, where it is fed to the stamps by two men (twelve-hour shifts). A self-feeder would save the labor of these men, and would cost but a few hundred dollars to put in. The battery discharges through forty-mesh screens, and can easily crush seven toxis per day, if the pan capacity were sufficient to amalgamate it. From the battery, the pulp runs into twenty-four settling-tanks (two men on eight-hour shifts), and from these is charged into ten pans of five feet diameter and a capacity of one and a half tons each. These pans are run nearly six hours, treat-ing four charges per twenty-four hours. They deliver into the five set-tlers, which are eight feet in diameter. These run about half as fast as the pans, and the charge remains in them two and a half to three hours. The tailings run through six blanket-sluices 130 feet long, 14" wide, 5' deep, with an inclination of 3°.
The pan charge is, for twenty-five ounce ore, about one and a half per cent salt, two pounds (and sometimes up to five pounds) sulphate of cop-per, and about 113 pounds of mercury; a bucketful of wood-ashes or a little cyanide of potassium is added to counteract the effects of candle-grease.
The steam for the pans is supplied by a tubular boiler forty-eight inches diameter and twelve feet long.
There are two twelve-inch iron retorts, capable of holding 1000 pounds, the usual charge of which is 700 pounds.
Wood costs eight dollars a cord, as against seven dollars at the mine. Mer-cury costs fifty cents per pound; salt, thirty dollars per ton, as against about twenty-eight dollars in Silver Reef. Teams are hired at five to seven dollars per day, including driver.
The Silver Reef ores are of fair grade, when the small cost of treating them is considered. The following data, taken from the books of the several mills working in the camp, give
THE AVERAGE YIELD OF SILVER REEF ORES.
The ores shipped from this camp previous to the erection of mills were necessarily of very high grade—averaging probably $150 per ton. After the erection of mills, much of the ore was mined by tributers, who paid the mills very high milling charges, and were, consequently, obliged to sort the ore to a very high grade. This is shown by the record of the Buckeye mill, where the average for sixteen months' work (4849 tons) was 44-98 ounces per ton, and where there was actually ob-tained, in net cash, $47.40 per ton of ore milled.
An equally high grade was milled in the Rock Cliff (Stormont) mill previous to August, 1878.
Since the Stormont Company commenced working its own mines, a much lower grade of ore has been treated; for, while about one fourth of all the bullion produced came from high-grade custom-ores, the aver-age net yield of 9893 tons milled was 20-63 ounces per ton; or, allowing that 86 per cent of the assay value was obtained, the ore contained on an average 24 ounces per ton.
The Barbee mill treated about 5740 tons of an average assay value of 29-10 ounces, and obtained net fine silver in the bullion 23-22 ounces per ton of ore.
The Leeds Company, in 1878, milled 12,064 tons of an average assay value of 19-42 ounces, and which yielded, in bullion, 15-11 ounces of fine silver per ton of ore.
RECAPITULATION.
Tons milled. Value of bullion Tons produced in ounces milled. fine per ton.
Buckeye Mill, February, 1878, to January 1st, 1879………………….4,849 44-98
Stormont Mill, September, 1878, to May 1st, 1879……………………9,893 20-63
Totals and averages……………………………………………………………....14,742 28-64
From this we see that the average actual yield in fine silver of all the ores milled by these companies, and which nearly all came from their own mines, was 28-64 ounces per ton; or, allowing for a loss of 15 per cent in milling, the ores contained an average of 33-70 ounces per ton. The ores milled previous to the date mentioned in this statement were of much higher grade, being mostly tributers' ore.
In assuming an average value of ore to be milled hereafter as 20 ounces per ton, I am far within the average of what these mines have produced in the past, and am providing for obtaining a much larger tonnage from the same area of ore-bearing beds, and at a much less cost per ton for mining.
Allowing a loss of 13 per cent in milling, which is justified by present practice in some of the mills, and a cost of $10 per ton for mining and milling, which is fully $1 per ton above actual present cost in some cases, 20-ounce ore, at the present price of silver, would yield at least $10 net profit per ton. Should it be desired at any time to increase temporarily this profit to $12, $15, or even $20 per ton, it can easily be done by sorting the ore more closely, and thus bringing its aver-age value up nearer to the average heretofore attained. I believe, how-ever, that the permanent interests of the company will best be served by milling a considerable proportion of that low-grade rock which is now thrown away after being mined, or is left unmined as waste.
From this it will be perceived that the average actual yield, in fine bullion, of 14,742 tons of the Stormont ores treated was 2864 ounces per ton. Since August, the average yield has been quite as high as ever before.
THE COST OF MILLING STORMONT ORES.
There were treated in the Christy M. and M. Co.' s mill, between January 1st, 1878, and May 1st, 1879, 14,248 ½ net tons of ore, of the average assay value of $32.86 ⅔, or 2542 ounces of silver, per ton. The tailings averaged $4.47⅔ per ton. The per cent extracted was, therefore, 86-38. The bullion obtained amounted to an average of 21•45 ounces fine per ton—equivalent to 84 per cent of the silver in the ore—and about 2- 38 per cent went into the slimes now on hand, and which will be reworked. The expenses of milling this ore are shown in the table which follows.
Per ton.
Labor and salaries..……………………………………………………………………………….....$2.85
Blue- stone, 2-1 lbs. at 15c…………………………………………………………………….……...31
Mercury, 1-22 lbs at 48-09c……………………………………………………………………….…58
Salt, 25-8 lbs. (?)…………………………………………………………………………………………..51
Fuel (wood, coal, and charcoal)…………………………………………………………………..1.31
General supplies…………………………………………………………………………………………..87
Hauling………………………………………………………………………………………………………..73
Contingent and legal expenses………………………………………………………………………41
Total.……………………………………………………………………………………………………….$7.57
COST OF MILLING AT THE STORMONT MILL.
1878 Ore Milled. Bullion Produced. Per ton. Net Cash received
Tons. Ounces Fine. Ounces Fine Per ton.
September,} 3,739 88,376-08 23-39
October,}
November,}
December,}
1879
January………..1,607 25,940-10 16-14
February..........1,335 26,107-28 19-55
March................1,827 39,592-87 21-67
April...................1,385 24,017-94 17-34
Total……………9,893 204,044-27 20-63 $21.00
Or, allowing that 85 per cent had been obtained, the ore averaged over 24 ounces per ton.
AVERAGE EXPENSES PER TON MILLED.
Per ton.
Labor and salaries……………………………………………………………………...$2.97
Blue-stone ( CuSO4), 1¾ lbs……………………………………………………………26
Mercury. 1-13 lbs…………………………………………………………………………...57
Salt, 20 lbs………………………………………………………...…………………………29½
Wood and charcoal………………………………………………………………………45½
General supplies……………………………………………………………………………..45
Incidentals……………………………………………………………………………………...12
Total…………………………………………………………………………………………...$5.12
Hauling…………………………………………………………………………………………2.58
Mining…………………………………………………………………………………………..8.27
Total…………………………………………………………………………………………$15.97
Improvement account, mine………………………………………………………….1.13
“ “ mill……………………………………………………………………….2.97
COST OF MILLING BY THE LEEDS COMPANY.
The Leeds Company, in 1878, milled 12,064 tons of an average assay value of 19-42 ounces, and which yielded, in bullion, 15-11 ounces per ton, equivalent to 79•41 per cent of the silver in the ore. The expense per ton of milling was as follows:
Labor and salaries………………………………………………………………………$2.20
Material……………………………………………………………………………………….3.15
Hauling…………………………………………………………………………………………..32
Assay Office……………………………………………………………………………………07
Total………………………………………………………………………………………….$5.74
During the six months ending December 31st, 1878, this total expense averaged $5.05 per ton; but during the present year, this has been further reduced to the following figures:
Labor…………………………$1.82-4
Material………………………..2.61-0
Sundries………………………….05-6
Hauling……………………………26-9
The chemicals used per ton of ore were about:
2 lbs. blue-stone.
1 ¼ “mercury.
20 “ salt.
A little cyanide or concentrated lye or wood ashes.
January—Total…………….$4.75-9
February "……………………..4.77-6
March "………………………….4.11-9
April "……………………………3.82-8
General average……………………………………………………………………$4.37-0 per ton
From these figures, we are quite justified in stating that Silver Reef ores not only can be treated in a large and economically-managed mill situated near the mines, at $4.50 per ton, but are now being treated at that figure. The reports from the superintendent of the company's mines continue to be of the most favorable character. In our next, we shall summarize the condition, prospects, etc., of this enterprise.
