OCR Text |
Show 4 INTER-MOUNTAI- Compressed Air in Mining. company to be $1.97 per ton, the average value of the ore milled in April having been $3.92, leaving a profit of $1.95 per ton. We are pleased to note that this statement has been widely copied, with favorable comment by the leading mining journals of the country, thus aiding the outside public in reaching a correct understanding of conditions in the Camp Floyd district. While much of the ore would elsewhere be considered very low grade, the cost of production per ton of ore, as well as per ounce of gold, is much lower than in any except a very few districts in JJV to various purposes in the working of mines. A recent press report says; C. M. OWEN. With the recent improvements in aircompressing machinery and the subordinate machines driven by compressed air, has come a corresponding increase in the use of this method of mining. In fact, where transmission is only required for a moderate distance, such as the world. Moreover, the great size of the ore bodies makes the operation of large plants desirable and large profits posple. Those individuals and incorporations that are continually sinking deep shafts, driving great tunnels and making tremendous strikes through the columns of the daily press do not always see themselves as others see them. The average reporter is a fellow, who uncomplainingly permits himself to be bored by these mining boosters, and whose only means of evening things up is to hand the daily dose over to the public. Thus we are given the daily progress in feet and inches of the tunnel, every change in the appearance of the country rock at the bottom of the Holy Terror shaft, and an exasperating lot of repetitions concerning unimportant Some companies have been strikes. known to go through forty hanging-wall- s and then never reach the vein. Pulling the leg of a reporter is not by any means the surest way to make a mine. The reporter simply winks the other eye as he puts the hot" item on ice. Some mines make altogether too many strikes. My advertisement in the Mining Review has brought me more business than any advertisement I ever carried in any paper, is the testimonial offered by Mr. F. E. Schoppe, a Salt Lake advertiser. Such voluntary statements are extremely gratifying to the publisher, as they afford conclusive proof of the excellence of this publication. as an advertising medium. good-natur- ed Rip-Snort- er The management of the Midsummer Carnival did a wise thing in making a s miners drilling contest one of the of the celebration, although possibly cash prizes would have stimulated keener interest among the miners. A celebration in this region without a rock drilling contest is incomplete. Every boom edition and boom publication recently issued at Salt Lake devotes liberal attention to the mines of this region, and the fact that mining is the chief industry of the country is receiving general recognition. Hugh McDonald, a Los Angeles mining operator, last week purchased 100,-0ounces of silver, ninety days delivery, at 72 cents, and after he had done this declared that silver would be cheap at 80 cents within three months. Salt Lake has good reason to feel proud of its daily press. No city of equal size is the possessor of so much newspaper energy and enterprise. feu-ture- inter-- mountain 00 . MINING REVIEW. N is usually the case in mining, a compressed-air plant driven by water power is the model plant of the day. While electric methods were daily advancing by mighty strides, compressed .air was, to some extent, thrust aside, and electric motors, drills and hoists were all the rage; but practical use has developed some disadvantages, and today air is being reconsidered more strongly than ever. The air drill is the only machine drill yet operated to any extent that will stand the Uutal treatment usually accorded it by the or- dinary, is a every-da- y freely-administer- ed miner, whose cure-a- blow with ll a sledge. With an equal original cost of erection, the air plant of today is both more economical in operation; calls for no expert in repairs seven-poun-d that cannot usually be made by the en- winzes, and the exhaust is always ac- gineer in charge; the loss by leakage, if any, can easily be detected; is easily conducted through crooked stopes or ceptable where bad air is encountered. Transmission for comparatively long distances is easily effected, with small loss, providing the conducting pipe has sufficient area in proportion to the demands of the plant, and the depreciation is small, while the first cost is not excessive. The Maxfield Mining company is toair day putting in a 200 horse-powcompressing plant, driven by Pelton wheels, which will operate their drills, hoists, pumps and motors, in all respects a modern plant of the highest grade, and which will reduce the cost of extraction of their ores to a very great extent, and no doubt their example will be followed by many mining corporations where the local conditions are favorable. Where mines are operated through long tunnels or shafts, the advantages of compressed air are very evident. The Honorine at Stockton is a very good example of this. The mine is now operated through a tunnel 3000 feet in length, and a shaft 4x9 feet is being sunk to connect with the ore bodies. This latter is in very wet ground, necessitating heavy pumping. The whole of the machinery in the mine is being operated by Ingersoll compressors, and includes drills, hoist and pump, which have done .excellent duty at a high efficiency. When the ore bodies are cut air haulage will replace the burro and Swede combination now in operation. Though the long-eare- d hay burner is economical in point of cost, his hauling power is limited. Many of our large mining properties have power running right past their dumps, only awaiting the investment of some capital to the more economical extraction of their ores. er The power is obtained from water conveyed about five miles in a twenty-inc- h steel pipe from the South Yuba canal to the power house In Boston ravine, giving a head of 775 feet, or a static pressure of 335 pounds per square inch. The pipe is a continuous riveted conduit, with no allowance for contraction or expansion. It has a capapower. city sufficient for The water from this conduit drives a Pelton wheel ei&rhteen feet six inches in diameter, built somewhat like a bicycle wheel, but with trusses to carry the power from rim to hub. It is run at 110 revolutions per minute. The wheel is mounted on a ten-inc- h shaft connected direct to two compound air compressors with cylinders eighteen feet, ten inches in diameter and twenty-fou- r inch stroke, to give a piston- speed of 400 feet per minute. The. air is compressed to thirtv pounds in the initial cylinders, which heats it to about 200 degrees Fahrenheit. It is then carried through the intercooler lying in the wheel pin. This consists of fifty one-in- ch copper pipes eighteen feet In length. The water from the wheel dashes over these pipes and cools the air down to its temperature by the time it passes into the second cylinder. Here it is further compressed to ninety pounds, and it then passes out through h a pipe about 1000 feet to a receiver in the shafthouse at the mine. From this receiver the air Is led 1,000-hor- se - six-inc- through a reheater, composed of a system of pipes placed in a furnace and so arranged as to have all the air pass over a heated surface, raising its temperature to about 350 degrees Fahrenheit, and increasing its volume about 43 per cent. For pumping from the mine, a compound differential group, of a capacity of 600 gallons per minute at 500 feet lift, is used. The air for the pump is reheated and sent down to the shaft in a magnesia covered pipe, but it is not reheated between the cylinders, which allows it to be discharged into the shaft at a comfortably cool temperature. It is expected that the compressors will deliver sufficient cold air at the shaft to develop power if used, and $3 a day will pay for the fuel for reheating the air sufficiently to produce power. The water for power costs the company about 1 cent per 1000 gallons, or $6.50 per cubic foot per second per day. Including the cost of fuel for reheating, this will make the cost of the raw material for developing the power almost exactly 10 cents per horse power per a ay of twenty-four hours, or say $3 a month. It Is found in actual practice one-ha-lf of the available compressor power being in use that by using about naif a cord of wood per day for reheating, 80 per cent of the theoretical power of the water is available at the mine. As the wheel has an efficiency of 90 per cent it will be seen that there is a loss of 10 per cent and half a cord of wood in developing and transmitting A Compressed Air Plant. power taken from the water The following details of a compressed air plant now in operation in the Grass wheel. Valley mines, California, illustrate the Two women at Ward, Col., have sold economy and adaptation of this power a mine for $75,000. . 175-hor- se 250-hor- se 140-hor- se |