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Show INTER-MOUNTAI- The Bennett Placer Machine. MINING REVIEW N The steel cross beams, twelve feet in length, are provided at each below the station of end with heavy jacks, which are used Seven miles Green River, on the Rio Grande West- to brace the machine and furnish a ern railway, the most ponderous, and solid foundation. When a gravel bank in many respects, the most wonderful has been cut through and it is desired machine ever built for handling: placer to shift the plant to one side in order gravel is now in operation. It is the to commence a new cut, these jacks invention of Mr. E. S. Bennett, a na- are used to lift it clear of the trucks, tive of Vermont, but a resident of Den- transverse trucks are substituted and ver, and was built for the South Park the machine moved to any desired poMining company of Denver. While at sition. this writing no clean-u- p has been made, Located upon the deck of the mareliable reports justify the assumption chine is the motormans cab, circular that the plant is a complete success, in form and provided with windows on and indicate that it is saving such a every side. This cab revolves about a high percentage of the values of the steel mast, and the shovel boom, weighGreen river gravel as to yield a very ing 7500 pounds, is also suspended from handsome profit to the owners. this mast, revolving with the cab. The A description in detail of the intriposition of the motorman is one requircate mechanism of the Bennett ma- ing a cool head, as he is required to chine is not possible at this time. It watch the operation of the various rests upon massive trucks and is moved parts of the machine, governed by difforward upon a track eight feet in ferent levers. These levers are so ar-trucks. THE BENNETT PLACER AMALGAMATOR. width, making an open cut through the feet in width. A gravel bank fifty-fiv- e great steel shovel raises the gravel into the hopper and thence it is screened, washed and concentrated, the values being saved by amalgamation. The machinery is operated by electricity, the current being supplied from a power-hous- e located some distance away. And it can thus be operated upon and down the river for a distance of several miles by simply adjusting the wires. Seven men, including the superintendent, are required to operate the plant and its capacity is from 2000 to 4000 cubic yards every twenty-fou- r hours, according to conditions. The illustration printed herewith Rives a correct idea of the appearance of the plant when in operation. Its extreme length, with the shovel extended, is eighty feet. The frame consists of two steel beams forty feet in length, which rest upon the wheel one-thir- j i j i j ; for holding the quicksilver and catching the fine gold. Jets of water enter the tank and keep the material in a constant state of agitation, sending the sand upward and forward, but affording opportunities for the gold to gravitate into one or another of the 600 pockets it is obliged, to pass in order to escape. A twelve-inc- h discharge pipe carries off the sand and debris. The weight of the machine is seventy tons and it filled thirteen cars. It was constructed at Denver by the Bennett Amalgamator company and taken to Green River last December. The power-hous- e is a building 76x24 feet, equipped with two eighty-hors- e power boilers, a high-spee- d automatic engine and power Edison dynamos. A Worthington pump, with a capacity of 1600 gallons per minute, supplies the plant with water through a twelve-inc- h pipe. An electric current of 500 voltage is sent over a No. 120-hor- se (on LINE OF RIO GRANDE WESTERN ranged that the motorman operates a portion of them with his hands and the others with his feet. When the machine is put into operation the great shovel, or dipper scoops d up one and yards of gravel at a load, and delivers it into a hopper. Thence the gravel passes into a double revolving screen, partly submerged in water, by which it is thoroughly washed and the coarse separated from the finer particles, the former being delivered to a steel carrier thirty-fiv- e feet long, which discharges the debris some distance away from the machine. The amalgamation tank, into which the fine sand, containing the values, passes, is of peculiar construction. It is twenty-seve- n feet long by twelve feet wide, with converging sides, so arranged that a cross section somewhat resembles a letter W. It is provided with rifiles set at every possible angle, so arranged that innumerable pockets are presented 5 o RAILWAY. copper wire to the amalgamator. While, as stated above, no clean-u- p has yet been made, the plates have been examined and tested and some of them scraped, and it is claimed the results show a saving of about 20 cents per cubic yard of gravel handled. If this is true the machine is earning about $500 per day and the cost of operation does not exceed $75. Twenty cents per yard is a higher value than the gravel was supposed to contain, and the gold is so extremely fine that it was not believed that it could be saved by any process. These bars extend for many miles along the Green river and the field is large enough to justify the erection of many such plants. It is not improbable that some of the old channels will be found to be richer than the gravel now being worked. Several more machines have been ordered by the South Park company and are now being built. As each machine costs |