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MODEEN MINE-HAULAGE PEACTICE. [Paper read before the Engineers' Club of Philadelphia on the 6th May, 1899, by Harry K. Myers.] To the engineer of the present day, in whose hands is the success or failure of the various mining operations, there are many forms of daily expense which he is desirous of curtailing; yet, on account of existing conditions, it is a serious problem as to the method most suitable for his special condition. One of the vital points in the production of any mineral is the transportation of the same from the face of the workings to the point of preparation, and it is almost impossible to conceive the vast amount of money expended in the various mines simply for underground haulage and maintenance of track. Previous to the past decade the question of economy was not so large a factor in the financial operation of mines, but at the present time competition in all lines is so great that the ruling prices are those at which the most advantageous mines can market their product with a fair margin of profit. In mines where natural conditions are not so favourable it is a matter of vital importance to devise or adopt methods whereby the product can be marketed at the going prices with a substantial profit. This is more especially the case in the mining of bituminous coal, with which the ruling profit is very small, and the cost of mine-transportation quite a large percentage of the price realised. Under a few special conditions it is possible to have animal-power more economic than mechanic, but with the recent improvements in the latter such favourable conditions have become exceedingly few. In this paper it is not the intention to go into special details of the construction of the different machines in mine-haulage, but rather to point out the most modern methods as applied in general to the coal-mines of this country. Particular attention is given to coal-mines for the reason that this tonnage is the maximum of any mineral product from underneath the surface, and on account of the low specific gravity it necessarily follows that the area worked over is a maximum, and, consequently, the power necessary for its transportation is vastly greater than for any other. To persons unaccustomed to underground workings and the rapidity with which the various gangways are advanced it is almost impossible to conceive the vastness of this subject; but when one considers that in one mine alone, with which the writer is familiar, there now exist 130 miles of track laid with iron and steel rails, and in the operation of this mine up to the present time there has existed 500 miles of such track on headings and air-courses and three times as much in rooms, making a total of 2,000 miles of road-construction which has been in this mine, of which about one-fourth now remains—if one simply makes an estimate of the track laid during the past year, based on a 6 ft. seam of coal, it is found that in the production of 200,000,000 tons it required 2,000 miles of track on headings and 5,000 miles in rooms. It may be said that all of this track was at such grades that it could be operated by some sort of traction, and, with such an amount of extensions each year with a total of 30,000 miles in operation, there is no reason why this class of work should not receive the full attention of the engineer and great economies result therefrom. Much has been written about preliminary, location, construction, maintenance of way, and transportation on steam surface-roads, but little has been said of the underground systems. At the present time there are fully 400,000,000 tons of different minerals produced annually over a total of 50,000 miles of mine-track, with an average haul of one mile per ton at a cost of 15 cents. In the transportation of this material it requires 100,000 mules, whose average life is four years each. To drive and maintain each mule will cost $600 annually, or a total of $60,000,000 annually for mine-transportation. With such an amount involved, it would appear to be a matter of a short time when animal-power would be a thing of the past and mechanic haulage universally adopted. . Of the various forms of haulage—viz., rope, steam-locomotive, compressed air, and electric— the first two have been used for a number of years. The wire-rope haul has been rather efficient, especially in straight headings and where the grades are heavy and against loads, but in the various attempts to use them in crooked gangways the cost of renewals has been very great. The mining type of steam-locomotive has been used considerably, but with the perfecting of mining-laws and the generally poor results obtained they are fast going out of use. The depression of business during the past year caused mining companies to examine modern methods, that they might secure a saving in this item of cost. About twenty years ago the question of compressed-air haulage in mines came up for consideration, but with the low pressures then advocated the range of the locomotive was such that very few plants were installed ; yet in that form it was a great improvement over the original tandem compound—viz., a string team of mules. The only disadvantage in compressed-air haulage is the size of the storage-tanks. As built at the present day for ordinary heavy work, they have the following dimensions : Height, 5 ft. to 5 ft. 6 in.; width, 6 ft. to 7 ft.; length, 16 ft. to 22 ft. Duringthe past ten years much discussion has arisen as to the merits of the forms of compound locomotives, but not until about two years ago was any attempt made to apply this principle to pneumatic locomotives, when the Baldwin Locomotive-works agreed to build for the Philadelphia and Beading Coal and Iron Company a Vauclain compressed-air locomotive, with the following dimensions : Diameter of high-pressure cylinder, 5 in.; diameter of low-pressure cylinder, Sin.; length of stroke, 12 in.; diameter of drivers, 24 in.; wheel-base, 54 in.; weight, 22,0001b.; capacity of storagetanks, 160 cubic feet; line-pressure, 800 lb. ; tank-pressure, 6001b.; working-pressure, 2001b. It was the intention to have this locomotive do the work of fourteen mules, and after a series of delays the plant was completed and the locomotive was thoroughly tested, much to the satisfaction of both builder and purchaser. After a most thorough trial of eighteen months two other plants were ordered, and at the present time another large coal company is having two similar plants installed.

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