Mining shaft

“ Of a hundred prospectors, ninety-nine die poor. The failures must be charged off to industrial waste attendant upon inherent conditions of the mining industry.
Again, in the development of a mine after it is located and proved in part, there is more unavoidable economic waste. The rock is blank and silent. It can only be explored by means of expensive drifts and drillings. In one mine at Bisbee, Arizona, a shaft was sunk which had drifts at the 600-and 900-feet levels, all without result. ”

“ At the bottom of this shaft was millions of dollars worth of copper and level after level of expensive workings; and some great stirring of the earth was cutting it off, crushing the bottle off at the neck. Every night, every shift, the swelling ground moved in, breaking stulls and square-sets like tooth-picks; and now with solid steel and quick-setting concrete they were fighting for the life of the mine. ”

“ The maximum output will depend eventually upon the rapidity with which development work may be extended. As levels and other subsidiary development openings can be prepared in inclined deposits much more quickly than the shaft can be sunk, the critical point is the shaft-sinking. As a shaft may by exertion be deepened at least 400 feet a year on a going mine, the provision of an equipment to eat up the ore-body at this rate of sinking means very early exhaustion indeed. ”

“ It is also cheaper to drive an adit than to sink an incline. If the topography is such that an adit can be driven into or beneath an ore body and thus expose it from a low elevation, the temptation is strong and along lines of good practice to do so. If the country is quite flat or nearly so, or, if the surface is such that, while rough, an adit of reasonable length cannot be driven to tap the valuable mineral and handle it economically, then it is good practice to decide upon a shaft mine. ”

“ Mill of the Pittsburg-Silver Peak Gold Mining Co., Blair, Nevada.
Water may be too scarce for the needs of a mine or its community. There may not be sufficient to supply boilers or a mill, or for the domestic purposes of the [89] workers. On the other hand, water may be so abundant in the mine workings as to prove a deterrent factor in profitable operation. With shaft mines, having deep workings and low grades of ore, if water must be delivered mechanically, the costs for such drainage are frequently prohibitive of mining. ”

“ New processes and more railroads have caused fortunes to be made out of low grade ore when there is enough of it. Some people would rather have a big lode of low grade ore than a pockety vein of rich quartz. As you know, abandoned mines are being leased all over the state, and abandoned prospect holes investigated. Well, there you are. This morning two mining engineers from New York came into my office with a tale of woe. They came out here to look about, and after considerable travel within a reasonable distance of railroads found an old prospect hole with a shaft sunk about fifty feet. ”

“ There is only a hole in the ground, where mining is carried on in much the same manner as in other kinds of mines. The shaft is sunk and lined with timbers to keep the dirt from falling in, just as in other mines. In working salt mines, however, water is almost as bad as earth, and therefore a layer of clay is put between the timbers and the earth. There are the usual galleries and pillars, with roof and floor of salt. The workmen try to get the salt out in lumps or blocks as far as possible, and so they bore in drill holes and then blast with dynamite or powder. ”

“ Again, it is a simpler and cheaper matter to maintain a mining tunnel in working shape than it is a shaft, particularly in bad ground. By the settling or "working" of the ground, a shaft may be thrown perhaps but slightly out of alignment and annoying interferences will be experienced in hoisting, especially when rapid and uninterrupted hoisting is necessary to maintain the desired output. While the same amount of disturbance does take place in an adit, it is an easy matter to readjust track grades while continuing regular haulage operations. ”

“ When our mining experts discover a mineral belt containing precious metals or copper, iron, lead, nickel, platinum, cobalt, quicksilver, manganese or any other ore used in manufactures and the arts, the first thing we do is to sink a shaft on the most likely ore chimney and at every one hundred feet in depth we run levels to develop it and if we continue to find ore as we go down and the ground requires drainage, we survey for a drainage tunnel that will drain the mine at the greatest depth, even if we have to run a tunnel ten miles. ”

“ Shaft-mining did not come in before 1450, when the stream tin was exhausted. The use of the adit cannot be traced back beyond the beginning of the seventeenth century. The only way of draining the mines was by rag and chain pumps, each consisting of an endless chain, broadened at intervals by leathern bindings, to fit snugly into a pipe from 12 to 22 ft. long, worked by a windlass at the surface. ”

“ It has, however, the disadvantage that a pillar of ore is locked up until the shaft is ready for abandonment. Moreover, as veins or lodes are seldom of even dip, an inclined shaft, to have value as a prospecting opening, or to take advantage of breaking possibilities in the lode, will usually be crooked, and an incline irregular in detail adds greatly to the cost of winding and maintenance. ”

“ It exists no more. All mine development work ceased long ago. There are green-stained carbonates on the surface, but there are no copper ore-bodies. The "mines" have been dismantled of their machinery and other equipment, and not even a lone watchman remains to point out to the desert-wayfarer the spot on which was reared the monumental mining-stock swindle of the century. Every dollar invested by the public is lost. ”

“ The want of capitalists in the mine country, and of practical skill in the boring, blasting, sinking shafts and galleries, oppose obstacles to the [Pg 160] successful progress of mining. There is but one regular hearth-furnace for smelting in the whole district; and that is on the modern plan of English furnaces. There are not over four or five regular shafts in about forty mines; there is not an engine, either by horse, steam, or water power, for removing water from the mines, several of which have been abandoned on this account, with rich prospects of ore in view. ”

“ Upon the bed-rock is a deposit, from three to four feet in depth, of gravel and boulders, in which the gold is hidden. This is called by the miners "pay-dirt," and to remove it to the surface and wash it is the end of mining. It is an expensive and laborious process indeed. The water has first to be controlled; and in mines of not too great depth this is done by a drain ditch along the bed-rock, commenced many claims below. In this all the claim-holders are interested, and all contribute their quota of the labor and expense of digging it. ”

“ But then, again, it is becoming plain to many experts in mining that, in working downwards from the surface itself, the future of their industry offers a wide field for the extension of the open-cut system. In proportion as power becomes cheaper, the expense attendant upon the removal of clay, sand, and rock for the purpose of laying bare the cap of a lode at a moderate depth becomes less formidable when balanced against the economy introduced by methods which admit of the miner working in the open air, although at the bottom of a kind of deep quarry. ”

“ When we have to use drainage tunnels for our mines we carry the water off from the mouth of the tunnel in a flume, placing quicksilver in the riffles, and if it is a copper mine we place scrap iron in the water and we also use the water for power to assist us in mining, so that at the present time we extract and reduce ore at a lower rate than in other parts of the world, for there is no wastefill management and no overproduction, for in all our mining operations we work those that cost the least, and we operate our coal mines in the same way. ”

“ These deposits are naturally the first to fail in productiveness, but the neighboring hills are formed of a gold-bearing quartz which is being crushed, night and day, by hundreds of powerful machines; and the works still pay ten thousand miners fair day-wages, besides giving the organized companies who employ them satisfactory dividends. Thus mining has been largely robbed of its adventurous character in this neighborhood, and perhaps also of most of its alluring charm, having become a sort of regular industry, like coal-mining, or even brick-making. ”

“ In shafts and levels for permanent use iron is an economical substitute. Wherever possible, new methods of mining are being introduced. Thus in the Lake Superior iron regions, the mine development is planned along lines almost unheard of ten years ago. In the first place the gravel which overlies the ore is stripped off, even if it is fifty feet thick. This is done with steam shovels, which load the gravel upon cars. These are then pulled away by one locomotive while a second places new “empties” in position to be filled. One shovel will load from 150 to 175 cars a day ”

“ Access to the buried deposits is gained by vertical shafts. Actual mining is now done to a large extent by continuous miners, machines which bore or rip the potash ore from the face and load it into shuttle cars in one continuous operation. The shuttle cars then transport the ore to conveyor belts which move it to the shafts for hoisting. Working conditions and safety are excellent and have led to high productivity from these mines. ”

“ A similar sacrifice in the shape of pillars is often necessary to support the surface, either to avoid injury to valuable structures or to prevent a flooding of the mine. As already noted large pillars must always be left to protect shafts, adits and the more important mine-passages necessary for drainage, ventilation and the haulage of mineral. In the early history of mining there was but little attempt at systematic development and working, and the mines were often irregular and tortuous. ”

“ Otherwise they can be employed only as wagoners drawing the ore to Tarascon.
The earliest mention of these mines is in a charter of the Count of Foix in 1293. For centuries the counts found the utmost difficulty in levying a toll on the iron carried out of the valley; the miners exercised their ingenuity in evading it, and overriding all the restrictions hampering their industry. Unhappily, for many hundred years the mining was not carried on by companies, but by individuals who grubbed where they would and carried on the works in the most wasteful manner. Now the veins of ore are giving out ”

“ Mine à La Motte has also proved an extensive deposit, and is still unexhausted. New Diggings, Shibboleth, and Richwoods, are among the discoveries of later date, which have yielded very large quantities of ore. But the mode of mining in the diluvial soil must exhaust it of its mineral contents, and direct miners, in after years, to the true position of the ore, in the calcareous rock. So long as the search continues in the soil, the business will partake of the uncertainty which now attends it, and which renders it rather an object of temporary enterprise, than a fixed employment. ”

“ In irregular and uncertain deposits this work of development should be kept at all times so far in advance of mining operations as to ensure a regular and uniform output. In some cases, where the barren areas are large, it may be necessary to have two or three years’ supply of ore thus blocked out in advance. A mine, however, may be over-developed, which results in loss of interest on the capital unnecessarily locked up for years by excessive development, and involves additional cost for the maintenance of such openings until they are needed for active mining operations. ”

“ From all of which it will be seen that nearly $4,000,000 may be given as the product of the mines up to May, 1870.
Nor are the mines, as a whole, decreasing in value. The promise of the past is the promise of the future. If results ave been encouraging, they may be fabulous. There are fields above and below unoccupied. It needs, simply, that capital, energy, and practical mining experience combine, to make this second to no hydraulic region in the State. The wealth is here, and it remains to be seen whether the forces that produce it are to bless with their coming and successful working. ”

“ It rises to the height of 3000 feet, the whole being coated with a thin mantle of the richest ore. In all directions it is covered with machines of various forms, horizontal and vertical galleries, tunnels and roads, and represents, as it were, a mine turned inside out. The whole of the operations are exposed to view, like those in the Carclaze tin mine in Cornwall, only in the former the ore is conveyed by tram-roads, galleries, and shafts to the bottom of the mountain, where they all unite in one main shaft, from which a tramway runs to the smelting-ovens of Eisenerz and Vordernberg. ”

“ Upon the Rand, South Africa, a territory dominated by Englishmen, every mine is equipped with its own mill, and all notions of mining cover the inseparable idea of local ore treatment. Here, in our country, there are many, many mines which have absolutely no means of treating their own products and the managers give no thought whatever to metallurgical or milling lines. There are, on the other hand, many companies that have erected private plants at their mines for the extraction of metallic contents from the ores. ”