TREATMENT OF SULPHUEET ORES AT CHARACTERISTIC MINES. 147
track, over which the ore is hauled to the mill by a small locomotive. This tunnel is drained by a wooden gutter situated in the center of the track line. At present ore is being quarried in the west cut (W) near the surface, from where it falls to the bottom of the pit (P), and is hauled to the mill through (A). The 40-stamp mill, which was not in opertion when visited, is situated about a quarter of a mile east of the mine, on the west bank of Lynch's creek. It is of the Western type, built by Fraser & Chalmers. The weight of the stamps is 900 pounds. The mortars are 15 inches wide at the lip, and are fitted with front inside plates and 30-mesh steel wire screens. The outside plates of silvered copper are S feet long by 54 inches wide. Below the plates is situated a line of pointed boxes, serving simply as amalgam-traps, which discharge 2 feet above the bottom to four Frue vanners with 6- by 14-foot belts. This is one of the most substantial and best constructed mills in the South. (Plate X.)
The chlorination plant consists of 2 revolving-pan furnaces, 2 barrels, 8 filters, 2 stock-tanks, and 8 precipitating-vats of the same construction and arrangement as at the Ffaile mine (see pp. 139-142).
When the mill was last operated (in 1S93), the object was to put through as much material as possible; 5 to 6 tons of ore per stamp were milled in 24 hours, with 4-inch drop, 90 drops per minute, crushing through a 20-mesh screen. Xaturally, the pulp flowed over the plates without a large portion of it coming in contact with them; and, with only 4 vanners, the ultimate loss in tailings was so great as to leave little if any profit. The concentrates that were obtained ran from $15 to $20. About 50 per cent, of the gold in the ores is free, and of the amount saved in amalgamation 50 per cent, was in the battery and on the inside plate. The cost of mining and milling at the Brewer mine, as practiced above, is given at 75 cents; and the total cost (including maintenance, salaries, etc.) at $1 per ton of ore mined.
Laboratory experiments with cyanide, and others with chlorination in bulk (the latter by Mr. P. G. Lidner), have been tried at the Brewer, but proved unsuccessful. In the latter part of 1S95 cy/anide experiments were again undertaken with reported favorable results.
