As more rich mineral discoveries are made in the 1880s, miners begin to improve their methods for recovery
By Steve Fiscor, Editor-in-Chief
By the mid-1880s, Engineering & Mining Journal (E&MJ) was hitting its stride as it approached its 20th anniversary. Readership was growing. The newspaper was still a 16-page weekly with engravings. Much of the coverage was dedicated to news items related to the American mining scene developing in the western frontier. Many of the reports were written by editors who were dispatched to document mining districts. They, however, also regularly published stories explaining what was happening abroad. These reports often carried a detailed history of those regions as well. The editors also routinely offered opinions, providing an American perspective.
The vast railroad network that would eventually bring more settlers to the West and return resources to the urban centers in the East was still being assembled. Power was provided by steam engines and compressors. Stamp mills, a means of crushing material by pounding it into pulp, were giving way to crushers, which grind the ore. The first gyratory crushers began to appear in the 1880s.
Some of the more established mining camps were yielding to new districts. The California placer gold mines and the mines working the Comstock Lode near Virginia City, Virginia, were showing signs of depletion. Meanwhile, in Montana, miners were about to discover the richest hill on earth, but just hadn’t realized it. The next gold rush was about to begin in the Black Hills of South Dakota.
THE COPPER MINES OF BUTTE MONTANA
April 28, 1877—The almost new district of Butte, in Montana, produced last year 800 tons of copper ore, carrying on an average 35 per cent of that metal and 15 ounces of silver per ton. When it is remembered that the district is but two years old, and that it lies 300 miles away from any railroad, this yield will not seem small….
The ores of the district are oxides (mainly the red oxide) and copper glance. On nearly all the veins carbonates are found on the surface which disappear as soon as depth is gained. In a few there is a preponderance of sulphide. The veins are quite numerous, and cut across the country like huge dikes, in places traceable by their colored outcrops for hundreds of feet at a stretch. They average from 3 to 20 feet in width, and carry a very regular seam of pay, which rarely disappears entirely.
Butte is, next to the Clifton district on the border of New Mexico and Arizona, the most prominent copper-producing camp in the West. Its growth has been very rapid, owing to the existence of very good silver mines in the same belt of veins….
Within the last few years the development of base metal districts in the West has been one of the most important features in its history. We have become quite accustomed to new and rich discoveries of the precious metals, and the excitement which attends these has, in a measure, hidden the less brilliant but equally valuable discoveries of lead, copper, and iron deposits. In time it is not unlikely that the value of the latter metals produced on the coast will approximate to that of gold and silver, and already it amounts to a very respectable figure. Last year the value of pig-lead and argentiferous galenas shipped East amounted—exclusive of silver contained—to about $4,000,000, while the yield of copper was about $1,000,000.
The production of the Butte mines this year promises to exceed 1,000 tons of 35 per cent ore. The proportion of silver carried in the ore is reported to be decreasing as greater depth is gained, which would be a rather favorable circumstance, unless it increased to a high figure. It is a pity, however, that the Butte ores must be transported more than 3,000 miles overland, at an expense of about $60 per ton, before they are smelted. This expense comes, of course, out of the pockets of the miners, and makes the profit of the producers so small that the mines are opened slowly and developed under great disadvantage. There is a most favorable opening in this camp for the erection of copper-smelting works….
September 8, 1883—The completion of the Northern Pacific Railroad will, we are convinced, mark the beginning of an era of prosperity to the mining interests, notably of Montana. The industry which will be most directly and immediately benefited is copper mining and smelting in the Butte District. With increased outlets to market and better facilities for procuring fuel, the cost of production and of marketing ought to be materially reduced, and the Butte smelter be better than ever able to compete in the markets of the world.
October 16, 1886—Governor Hauser, in a report to the Secretary of the Interior, makes an excellent showing of Montana's progress in mining and other industries during the year past….
There is every reason to believe that the products of our mines will steadily increase from year to year until Montana stands reliably foremost among the States and territories as a producer of the precious metals.
The Alice mine has erected fine new hoisting works at an expense of $12,000.
A new steam stamp has been added to the Anaconda works, with a capacity in operation of 250 tons of ore a day. The ore-crushers, which have been stationed next to the ore-bins, have been taken down and out, and will be used in another place. The old concentrator building has been changed materially. The company is at present rebuilding the chutes at the St. Lawrence mine as well as the Anaconda. Large amounts of lumber are daily hauled to the mine for that purpose.
The Blue Bird mill goes steadily on at a cost of $250,000. The company has also erected hoisting-works at an expense of $40,000.
…a very rich but singular discovery bas been made in the Lexington [mine]. It has always been a silver mine. For ten years, it has been a producer of silver ore. On the 800-foot level, where prospecting has been active of late, and where a chute of the usual character of ore was expected, a body of distinctively copper ore has recently been struck. The size of the strike has not yet been developed. The ore is a pyrites of a bright and beautiful color, and assays from 25 to 30 per cent copper and about 80 ounces in silver. Of course, it can only be treated by smelting: The discovery dispels the idea that copper may not abound at great depth under all the silver mines in the vicinity of Walkerville. The freak of the Lexington is as interesting as it is important.
THE AUTOMATIC AIR COMPRESSOR
September 4, 1886—Mine operations and tunnel-boring are not usually accomplished by the aid of automatic machinery, owing to the peculiarity of the work and crude appliances presented. Operators and contractors have not taken kindly to machinery that very soon proves to be more expensive than the old methods. But experience has demonstrated that an air-compressor, to be successful and economical, must be self-governing, for the reason that rock-drills, pumps, etc., that are run by compressed air are of necessity irregular in their action, so that the quantity of air used by them must vary….
The automatic mechanism is a part of the machine, and is always on hand to govern the compressor at all times and under all circumstances, and of course accomplishes in a month much saving of labor machinery and fuel. The machine throughout is strong and of excellent construction. It is built by the well-known Morris County Machine and Iron Company, at its mining machine-works in Dover, New Jersey.
THE COMET CRUSHER
September 8, 1883—Crushers of the well-known Blake type, having a reciprocating action, do work only during a part of the time. The idea of so changing the design that work is continuous, naturally suggested itself, and it is to this class of machine that the Comet crusher belongs, the construction of which is shown in the accompanying engraving. In the jaw-crushers, the rock is broken by the approach of two planes surfaces; in the Comet crusher, the planes are converted into circular surfaces, the reciprocating being changed to the rotary motion of the inner crushing surface, which is mounted eccentrically on the shaft. The distance between a given point of the fixed outer surface and the rotating inner surface varies therefore during every revolution between the maximum and minimum. During one revolution, therefore, the rock between the two surfaces is once subjected to crushing action, which is thus continuous….
Messrs. Fraser & Chalmers of Chicago, who are the builders of the Comet crusher, attach the breaking head to the upright shaft by means of bolts, avoiding the use of zinc….
The crusher, of which five sizes are made has an excellent record for crushing material…The second drawing shows a design for an entire plant, the points of which will be readily understood.
THE BLACK HILLS
June 3, 1876—A pamphlet of 71 pages, now lying before us, contains Chapters V., VI., and VII. of the forthcoming Report of the exploration of the Black Hills of Dakota, made last year, under the direction of the Commissioners of Indian Affairs, by Walter P. Jenney, E.M. These chapters give an account of the general geology, mineral wealth, climate, and rainfall, and natural resources of the region….
…Mr. Jenney speaks favorably of the conditions for cheap mining, and of the prospects of a number of the districts; but his final conclusion is somewhat of a damper. He says: “There is gold enough to thoroughly settle and develop the country, and, after the placers are exhausted, stock-raising will be the great business of the inhabitants, who have a world of wealth in the splendid grazing of this region.” This is damning with faint praise.
Meanwhile, the present business of the inhabitants is saving their scalps from the Indians. Of course, we must approve the determination of the Government to protect the lives of citizens, even though, by disobedience to express proclamation, they may have forfeited their claim to protection. But we think the blood that has been, and will be, shed in this affair too great a price for the booty sought; and we trust the follies of the past will not be crowned with an expensive purchase of the Indian right to the Black Hills.
A little more than a year later, E&MJ would report that 725 stamps, four arastras and a smelter are operating in the Black Hills. These mills are located in the upper towns of the main gulch from Grayville west, at Lead City, Pennington, Strawberry Gulch and the smelter at Galena. They provide updates on about a dozen mines working the Black Hills gulches.
GOLD MINING AND PROCESSING
In a September 4, 1886, contribution, Cost of Mining and Milling Free Gold Ores, Hamilton Smith Jr. provides insight about the activity at American gold mines at the time.
The gold from all the mines for which the following comparisons are made is obtained nearly altogether by the simplest methods of amalgamation and concentration.
The ore coming from the mines is first passed over grizzlies: the larger pieces of rock that do not drop through the grizzlies are then crushed by rock-breakers into small fragments. The fine ore is then fed to the stamp mills, which consist of batteries each having five stamp-heads dropping in a cast-iron mortar. Electro-plated sheets of copper are generally placed inside these mortars, into which quicksilver is introduced. A sufficient supply of water is constantly poured into the mortar. The finely crushed ore and amalgam are discharged from the side of the mortar through finely punched or slotted screens of sheet-iron, and the escaping “pulp” passes down in a thin sheet through inclined sluices over sheets of copper also silver plated. The tailings flowing from the sluices are in some cases passed over rough blankets, or through buddles or vanners, in order to concentrate and save the heavy particles of either amalgam or pyrites. In all the reduction-works that will be spoken of, by far the larger portion of gold is obtained in the mortars and on the copper plates….
California—The Sierra Buttes and Plumas-Eureka mines are situated some 35 miles by wagon-road from the Central Pacific Railroad. Wood for timber and fuel is abundant and cheap. Mining labor costs about $2.50 a day. Water-power is used for crushing at the Sierra Buttes; at the PlumasEureka, both water and steam are used. The lodes worked are of good size, averaging a thickness of perhaps 8 feet, and are reached by ad1t levels.
At Sierra Buttes, 93 stamps were running for first six months and 60 stamps for last six months, being an average of 76.5 stamps; 54,479 tons mined, yielding $380,145, or $6.98 a ton.
The Sierra Buttes and Plumas-Eureka Mines are owned by English corporations under the same general management, and have been operated in a very judicious and economical manner; in these respects, their management compares most favorably with that of other foreign mines owned in England.
Dakota—The Homestake, Father de Smet, and Caledonia mines are situated near the town of Deadwood, a distance of some 250 miles from the Union Pacific Railroad. A branch of the Chicago & Northwestern road has in the last two or three years been approaching Deadwood, thus diminishing the length of wagon transportation; this branch will reach the town some time during the present year. Wood for fuel and timbers is brought to the mine by means of a narrow-gauge railroad, a distance of 15 or 20 miles. Water for mill purposes is more than usually expensive. Mining labor costs from $2.25 to $3 a day. The lode or deposit worked is from 15 to 70 feet or more in thickness. The ore is hoisted to the surface by steam-power. The deepest shaft has a depth of about 500 feet. Steam is used for power by the several mills.
There are two mills attached to the Homestake mine—one of 80 and the other of 120 stamps. These 200 stamps have been in continuous operation for about six years. From 1882 to 1885, production has increased from 179,000 to more than 213,000 tons worked at a yield of about $6.00 per ton. The Father de Smet mine has 100 stamps crushing a little more than 100,000 tons with a yield of $3.40 per ton.
A VISIT TO LEADVILLE
An E&MJ correspondent detailed his trip to Leadville, Colorado, in the July 21, 1883, edition. To the lover of grand and majestic scenery, a journey from Denver to Leadville, via the Denver & Rio Grande Railroad, is a treat not soon to be forgotten. Nothing could be grander than the Grand Canon of the Arkansas, and no visitor from the East should miss seeing it.
Arriving at Leadville, all was hurry and bustle, and trade was very brisk, as the mines were all making their monthly payment of wages. Harrison avenue is filled every day with busy people, hurrying to and fro; while in the evening, the foot-walks are almost impassable from the crowd of toilers, whose day’s work is over and who are out seeking amusement and social intercourse with friends.
Leadville and its surroundings have been so often described that it must be pretty well known now; nevertheless, for the sake of those who may not know, or who may have forgotten, I may say that it lies on a gently sloping plateau, between two gulches. at the foot of the mountains bounding the eastern side of the Arkansas Valley, and about five hundred feet above the river-bed. Around it, to the north, east and south, and within a radius of about five miles, lie the mines which are the chief source of its wealth. To the northeast, about one mile away, is Fryer Hill, containing the celebrated Robert E. Lee mine, the Matchless, Chrysolite, Little Pittsburg, Amie, Little Chief, and several others. Eastward, on the suburbs of the city, is Carbonate Hill, with the Morning and Evening Star mines, the Catalpa, Henriett, Agassiz lease, Gonabrod, Leadville Consolidated, and others upon it. Behind it lies the most celebrated part of the camp at present, namely and leases, Iron Mountain, possessing in its depths the Silver Cord….
The largest producing single mine is the Silver Cord, where I was most courteously received by T.S. Wood, who at once proposed that I should go down the mine and see for myself. So having donned some mining toggery, I descended, and, in charge of the foreman, was shown a part of the mine where they were the busiest. No. 3 station contains one of the most magnificent breasts of solid hard carbonate I ever saw. At present, it stands 25 feet by 20 feet of solid ore. In places it has reached a depth of 60 feet. Here and there, the sparkle of large lumps of galena could be seen. Altogether, it was a splendid site, even for one who was not a shareholder. It was impossible, in the time of my disposal, to visit the other parts of the mine, which runs on an incline 800 feet deep into the hill. I was told that they had struck it quite as rich in other parts. The output runs between 3500 and 400 tons per month and the ore contains gold as well as silver, and a considerable quantity of lead.
THE DIAMOND MINES OF SOUTH AFRICA
A story written by Gardner F. Williams (November 13, 1886) puts a burgeoning diamond discovery into perspective.
These mines are situated in Griqualand West, which is now a part of the Cape Colony. The town of Kimberley is in latitude 28° 40’ south, longitude 25° 10’ east, about 640 miles northeast of Cape Town, and 450 miles from Port Elizabeth on the east coast. It is connected with these towns by a railroad that has been completed during the present year. The mines are located in a desert country, resembling the desert portion of Arizona. The elevation above sea-level is about 4000 feet. The climate is exceedingly hot during the summer months.
Diamond Deposits—There are four large diamond-bearing deposits at Kimberley, all lying within a radius of one and a half miles, having the De Beers mine as the center. These are named the Kimberley, De Beers, Du Toit's Pan, and Bultfontein mines.
The first diamond is said to have been found in 1867 by some Dutch children on a farm near Hope Town, about 90 miles south of Kimberley. In 1869, natives discovered the Star of Africa, which weighed 83 carats. The discovery of these diamonds lead to a rush described by the writer: The year 1870 saw the banks of the Vaal River suddenly, as by magic, densely populated with tents of huts of every size and shape. The river diggings were the precursors of the great mines.
In July, 1871, the famous Kimberley mine was discovered. This is by far the richest of all the mines. The farm, on which are situated the De Beers, Kimberley, and St. Augustine mines, was purchased by the government of the Cape Colony for £100,000. The De Beers and Kimberley mines are held and worked under the old system of paying to the government a monthly license fee of ten schillings for each claim….
In 1873, Kimberley had grown to be a town, with a population of from 20,000 to 25,000, while neighboring towns and camps were nearly deserted. In 1876, the method of washing the diamond bearing ground superseded the old method of dry sorting; and the percentage of diamonds saved was largely increased, thus proving that a large percentage of diamonds had been thrown away while the old dry sorting was in vogue. The debris from the Kimberley mine was sought after and washed, in preference to mining virgin ground in other mines….
The surface [of the Kimberley mine] was originally blocked off into claims of 31 feet square, and, within a week from discovery of the first diamond, about 1500 licenses to work claims had been granted….
The original system of mining the Kimberley ground, namely, by open quarry, was without a doubt the best for a depth of 200 ft, because the mine could have been worked in no other way while the claims were operated by individual owners….
In whatever manner the diamonds may have been formed, they must have crystallized before they were deposited in the mass in which they now occur. No diamonds have been found either in the shale or in the hard rock surrounding the “blue,” as might be expected if the diamonds had crystallized where they are found….
The miners would soon choose another method for working the mine, by sinking shafts into the solid ground outside the mine, and drifting to the “blue” ground, and then the deposit was mined by drifting and stoping. The miners found the blue ground to be richer in diamonds the deeper they mined. However, the amount of water they hoisted amounted to 13 million gallons per year at a cost of 6 pence per load of 100 gallons.
THE MINES AT RIO TINTO SPAIN
November 17, 1883—Among the most remarkable mineral deposits known, those of Rio Tinto, Spain, possess more than ordinary interest for Americans, because the company working them is one of the leading competitors in our own markets of the miners of pyrites for sulphuric acid manufacture, and at the same time the one that has during the past few years rivaled our copper producers in placing growing quantities of metal on the markets of the world. An elaborate report by a leading French engineer, M. E. Cumenge, and printed during the current year, throws a flood of light on the present condition and the future of the great mine, and contains many points which deserve the attention of engineers and metallurgists.
The deposits of the Province of Huelva, of which Rio Tinto is one, were known to the ancients, Phoenicians and Romans, who, as evidence of their activity, have left more than 180 miles of workings in the Rio Tinto deposit alone, and accumulated no less than twenty million tons of slags and cinders on the neighboring dumps. A metalliferous zone extends in approximately an east and west direction for a distance of twenty leagues from El Castillo de las Guardias, north of Seville, beyond the Portuguese frontier. It is four leagues wide. Rio Tinto is situated towards the eastern end of the zone, while the mines of the Tharsis Company are located toward the west, there being a series of minor deposits between the two, among them El Castillo, Peña de Hierro, La Cueva de la Mora, Sotill, St. Elmo, La Joja, La Zarga and some others, some of them, like the Buitron mine, being partially exhausted….
The Rio Tinto deposit consists of a compact mass of cupriferous iron pyrites occasionally showing patches of gray copper, blende, and galena. The ore as mined is divided into two classes, by sorting according to its contents of copper, about one quarter of the quantity being exported, while the rest is treated on the spot. Samples are taken from every car of ore loaded, and, the entire sample being crushed, a daily average assay is made. M. Cumenge estimates the general average for the year 1882 at 2.88 per cent of copper. The export ore, 250,000 tons annually, is sold by the Cornish assay, which understates the true percentage by 0.75 to 1.0 unit, so that the actual percentage of copper in this class of ore lies between 3.25 and 3.50 per cent and from 48 to 50 per cent of sulphur. The ore treated on the spot carries on an average 2.50 per cent of copper….
Until now, all the estimates of the engineers have referred solely to the mass of ore worked by an open cut, which until a recent date furnished almost all the ore. The ancient workings, which, to a certain depth, were numerous, had evidently the object of mining the seams of richer ore in the mass of average grade, and this fact alone explains the increase in the percentage of copper when virgin ground was opened. Experience has proved that, in taking five millions of tons out of the open cut, almost the entire mass is uniform and essentially composed of compact iron pyrites, with spots of copper pyrites and black sulphide. In the future, however, the fact must be taken into account that the Western part of the South vein, known as the San Dionisio lode, is more complex. The copper becomes a more important factor. Pure copper pyrites is not found in spots, but true seams, and other copper minerals become more abundant, so that the average thus far is 4 per cent of copper, and selected lots assay from 7 to 8 per cent. The Rio Tinto Company bases great hopes upon this part of the ground, and has begun great underground workings….