Bisbee daily review., 1920-04-18
CONCENTRATQRA SHATTUCK
 MINE, BUILT ON ORIG NAL
 PLANS, |S UNIQUE IN AMERICA
Local Plant Handles Ores of Lower Grade Than Others in Country; Is Result of Scientific Experiment. Made by Locally Employed Men and Handles Ore Con
 taining Gold, Silver and Lead


 existence operating on low grade OK idized lead and silver ores. Several unsuccessful attempts have been made in different parts of the coun- try to mill similar ores and ill every case the grade of the ore was much hihger than that handled by the Shat tuck concentrator.
 The success of the Shattuck mill technically is due to several factors, the most important of which are: n the introduction of a special applica- tion of the Notation process. known as sulphidizing, to recover values in the slime heretofore not considered amenable to flotation; (2) mill cor rectly designed and mechanically equipped; (3) a simplified, workable, cess capable of making high recov- cry of the mineral values, and finally to (4) efficient operation and man- agement
 Points of View
 The mill might be viewed from three different angles, metallurgically, me chanically and economically. The metallurgy consists of the milling problems and processes; the meChani- cal description covers the methods ana machines used, and the economies of the plant are the results obtained by the combined use of certain processes and mechanical equipment. This will be the general method used here with out attempting to be technical.
 The ore for the mill is mined from the Shattuck mine by carefully work- ed out modern methods of extraction, at the rate of about 300 tons a day at present. The ore is transported down the hill from the mine by aerial tram way, loaded into E. P. & S. w. ore cars, and delivered to the mill bins. These bins for the crude ore hold about 1000 tons, are of the 'V' type, constructed entirely of heavy timbers and lined with steel plates. The ore care are spotted, three at a time, di- rectly over the ore bins and dumped.
 MetalIurgical Process.
 The ore occurs in the mine III the form of a siliceous breccia and natur- ally silicia is the chief gangue con stituent Iron, mostly in the form of d black crystallized specularite, to- gether with variable amounts of li monite, are the. other most important gangue materials. Lime and alumina occur only in small amounts, and the sulphur content varies from trace to 0.4 per cent.
 Cerussite or lead carbonate, horn silver and gold are the valuable min erals. The lead is practically all in the form of carbonate, but with The silver occurs in the form of com mon chloride The gold, silver and lead are apparently in no way asso- ciated or combined. The valuable minerals are of considerably greater specific gravity than the gangue, or worthless rocks, so the mineral par ticles larger than 200-mesh, when ire from gangue are readily concentrated by gravity methods.
 Metuliurgical Problem.
 The metallurgical problem, then, is to recover the gold, silver and lead in the form of a concentrate and discard the worthless gangue. This concen- trate must contain, of course, suffi- ciently large percentage of the values contained in the original ore to pay nr milling, smelling and selling, and still return d margin of profit. In the case of the Shattuck ore this problem is complicated by the fact that the mill must recover three separate and dis tinct minerals, all of different physi- cal characteristics.
 The crude ore, as il comes from the mines. contains the values for the most part locked up in the rocks, so the first step in dressing the ore con sists of crushing it down to about 9s- inch Jumps, in order to free more of the valuable minerals from the gangue. This work is done in the crushing plant before the ore is sent into the mill bins. The crushed rock is car ried to the fine ore bins in the high est part of the mill on a long conveyor belt and is automatically dumped into the bins.
 Milling Process.
 The milling process. in brief, con sists of drawing the ore from the fine ore bins Cat about 9s-inch sige), sig ing over a quarterinch screen. sending the courser size to the gIndlng mills and the finer size over concentrating tables to extract the free lead, gold and silver. The discard from the con centrating tables. together with the oversize from the screen, is ground to 65-mesh and run through "classi fer" which separates the product into sand and slime. The sand is treated or the concentrating tables and the cIi io tpaatod hv zulnhidiziuU and