Hydraulic mining

“ The mining interest respects no rights but its own. A farmer may have his whole estate changed to a barren waste, by a flood of sand and gravel from some hydraulic mining up the stream. If a fine orchard or garden stands in the way of the working of a rich gulch or bank, orchard and garden are doomed. They are torn down, dug out, washed to pieces, and then washed over side hills. Where the process of hydraulic mining has been, or is being carried on, the country presents an appearance of devastation and ruin that is scarcely imaginable; forming a frightful blot upon the face of nature. ”

“ This hydraulic mining seemed to be most in favor there, and the power developed by some of these streams was immense. The momentum acquired by the water in its long descent, sufficed to melt huge hills of clay and gravel very quickly; and instances were reported where men, and mules even, had been killed by being struck by the water, as it issued from the pipes or hose. The men engaged in mining were rough and hirsute, as miners everywhere are; but they looked bright and keen, and as if they believed in California and her future, come what might. ”

“ Hydraulic mining has for the most part been confined to the country of its invention, California, and the western territories of America, where the conditions favourable for its use are more fully developed than elsewhere—notably the presence of thick banks of gravel that cannot be utilized by other methods, and abundance of water, even though considerable work may be required at times to make it available. ”

“ Immense pipes were laid and altogether millions of dollars were invested in hydraulic mining. The water coming down under heavy pressure from the mountain reservoirs passed through giant hose which would carry a hundred miner’s inches, and, striking the mountain side with terrific force, washed away the earth from the rocks. Down fell the sand and gravel into sluices or boxes of running water where cleats and other arrangements caught and held the gold, which was heavy, while the lighter mixture was carried out into the canyon. ”

“ In some portions of the mountains hydraulic mining is more common than quartz-mining. Years ago many of the rivers occupied different channels from their present ones. The gravels of these old channels in the Sierra Nevada mountains, and in other parts of the West where gold-bearing veins occur, are rich in gold. In these channels the gold is so deeply buried that it cannot usually be obtained by means of pick and shovel. In order that the overlying gravel may be removed as cheaply as possible, water is supplied by means of ditches, often many miles long. ”

“ A complete outfit for boring with the diamond drill includes a steam engine and boiler, diamond crown, lining tubes, rods, and various minor accessories.
Hydraulic mining is the cheapest known method of recovering gold. In four years the North Bloomfield Mining Company of California worked 325,000,000 cubic yards, which yielded only 2.9 cents of gold per cubic yard, and realized some profit. Very poor gravel will pay when the conditions are good. ”

“ In the early mining operations, gold had been obtained by digging the gravel by hand and washing in pans or in the devices known as cradles and sluices; but when the richer deposits were exhausted and lower grade gravels had to be worked, efforts were made to find means to mine on a larger and cheaper scale. The result was the introduction of what became known as hydraulic mining, a process invented in 1852 by Mr. ”

“ With water-power at the mine, winding engines can be operated by direct hydraulic application with a gain in economy over direct steam, although with the sacrifice of control and reliability. Rods for pumps can be driven directly with water, but this superiority in working economy means, as discussed later, a loss of flexibility and increased total outlay over other forms of transmission to pumps. As compressed air must be transmitted for drills, the compressor would be operated direct from water-wheels, but with less control in regularity of pressure delivery. ”

“ It is of great importance in mining with the cradle, to have the cradle placed within four or five feet of the hole from which the pay-dirt is obtained, and to have a good supply of water at the head of the cradle, and then to have a good descent below the cradle, so that the tailings may all be carried away by the water, so as not to accumulate. The rocker washes about one-half the amount of dirt that can be washed by an equal number of men with the tom, one-fourth of what can be washed with the sluice, and one-hundredth of the amount that can be washed with the hydraulic process ”

“ More water is required for piping down banks than for washing the dirt; and often the sluice is almost idle for want of dirt, while the water, after being thrown against the hillside, runs away without doing any service at washing. Blasting, therefore, by loosening the earth, enables the hydraulic miner to have an abundant and regular supply of dirt in his sluice, at an expense much less than the cost of manual labor to dig the bank down with pick and shovel. ”

“ 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. ”

“ The smaller mines, besides being generally more superficial, are commonly situated upon acclivities, and thus an accumulation of water seldom incommodes the mining; but the larger ones are more frequently in valleys, and soon filled with water, which it is necessary to remove. This is effected by a common and cheap hydraulic Chinese machine. Sometimes a canal is made to pass close to the mine, for the purpose of facilitating the labor of removing the upper strata of sand and clay, which are thrown into it as extracted, and thus carried off by the stream. ”

“ Many of these claims will yet afford from five to ten or more years' profitable labor to their owners, before the lead itself within them is exhausted. As in some of them quartz veins and poorer paying gravel have been found, many of them may be valuable to work from the top down as hydraulic claims. ”

“ Dredging requires little water as compared with that required for sluicing and elevating, and this water can, in many dry localities, be supplied at small expense, where a supply for hydraulic work or elevating would cost a very large sum, or be impossible at any cost. ”

“ The artificial ditch supplies the want. The ditches are made by large companies, which sell the water by the "inch." An inch of water is as much as will run out of an orifice an inch square, with the water standing six or seven inches deep in the flume over the orifice. The depth of water over the orifice is called the "head." The orifice is usually two inches high, and as long as necessary to give the amount of water desired. Nobody wants less than ten or twelve inches for mining: a "sluice-head" is about eighteen inches; a "hydraulic-head" is from forty to two hundred inches. ”

“ The miners do not support the earth by timber or pillars, as they should; the result is that the whole plot of about two hundred acres is gradually sinking, and this will eventually ruin the industry in that part of the deposit. In another part of the same field, a French company has purchased forty acres, and it is mining the whole tract and hoisting through one shaft by steam power. In that shaft they have sunk to a depth of six hundred feet, and are troubled with water and petroleum. These they pump out very much the same way as in coal and other mines, worked in a scientific manner. ”

“ 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. ”

“ 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. ”

“ Where the amount of water is limited,—up to, say, 50,000 gallons daily,—and where the ore output of the mine permits the use of the winding-engine for part of the time on water haulage, there is in the method an almost total saving of capital outlay. Inasmuch as the winding-engine, even when the ore haulage is finished for the day, must be under steam for handling men in emergencies, and as the labor of stokers, engine-drivers, shaft-men, etc., is therefore necessary, the cost of power consumed by bailing is not great, despite the low efficiency of winding-engines. ”

“ Of course in large alluvial claims, where capital is employed, such appliances are superseded by steam puddlers, buddles, and other machinery, and sometimes mercury is used to amalgamate the gold when very fine. Hydraulicing is the cheapest form of alluvial mining, but can only be profitably carried out where extensive drifts, which can be worked as quarry faces, and unlimited water exist in the same neighbourhood. When such conditions obtain a few grains of gold to the yard or ton will pay handsomely. ”

“ In some of the claims the pay-dirt lies within two feet of the surface; in others it lies much deeper, but all the superincumbent matter is swept away.
Water is the great agent of the placer miner; it is the element of his power; its amount is the measure of his work, and its cost is the measure of his profit. With an abundance of water he can wash every thing; without water he can do little or nothing. Placer mining is almost entirely mechanical, and of such a kind that no accuracy of workmanship or scientific or literary education is necessary to mastery in it. ”

“ 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. ”

“ Twenty yards from this was a cone of black earth twice the height of a man. This was their pile of pay dirt. For five days now, they had been working on the second 35 mine of the seven. The pay dirt they had struck was not as rich as they hoped to find, but it would repay the labor of sluicing. It was growing richer each hour. They hoped in time to uncover the mother-lode. This would pay for panning and yield a rich reward.
It was placer mining. Beside the mine entrance stood a steam thawer, a coal-heated boiler such as is used for driving a sawmill or grist-mill engine. ”

“ But accidents due to a flooding by surface water are not always to be obviated. Sometimes when a stream crosses the line of outcrop the water will break through into the mine and flood the lower levels in an incredibly short space of time; and this too when good judgment and prudence have been used in leaving sufficient coal for protection. The continuity and character of the strata lying between the earth’s surface and the coal face cannot always be determined. It is not often that accidents from flooding occur while mining is going on under large bodies of water. ”

“ The seam is worked on successive levels, but, even then, it is impossible to prevent constant accidents from the fall of coal or the sudden collapse of a roof. Take it the world over, and ten miners are killed every day in collieries alone. I told you coal mining was dangerous. ”

“ Another important problem that constantly confronts the mining engineer is that of drainage. Mines are, of course, great reservoirs for the accumulation of water, which must be drained or pumped out continually; and as the shafts are sunk deeper and deeper it becomes increasingly difficult to raise the water to the surface. ”

“ In connection with pumping it may be said that a great deal has been discovered and invented during this century concerning the force and utilisation of jets of water and the force of water flowing through orifices. In the art of mining, a new system called hydraulicising has been introduced, by which jets of water at high pressure have been directed against banks and hills, which have crumbled, been washed away, and made to reveal any precious ore they have concealed. ”