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Show Treats Lower-grade Ores p : : ) ' i - " ' ' ', - 'j I ' , - I , ' A. 8. & R. plant at Garfield. During the past twenty years, two factors have greatly changed the mining Industry of Utah and the change or ore available for the smelters. During the past twenty years the direct smelting oxidized lead-silver ore was slowly depleted and changes In metallurgy were necessary. neces-sary. As mining developed to deeper levels, much complex sulphide sul-phide ore was developed and it was necessary to add another complete practice in the treatment of this low grade ore. This practice was selective flotation, a mill to eliminate elimin-ate the waste or gangue from the ore and separate the metals. The Murray plant of the American Amer-ican Smelting & Refining company was originally equipped with eight blast furnaces, having a capacity of approximately 1G00 tons per day, the largest smolter in Salt Lake valley at that time. Today the Murray Mur-ray plant smelts its entire tonnage through one blast furnace. While this Is due somewhat to Improvements in practice, the principal prin-cipal reason lies in the fact that the production of lead ores in Utah is steadily declining. This reduction has been accompanied by a decline in grade and by increased mining costs. The continuation of this trend will further reduce tonnages in the future, the only check being further economies in mining, milling, mill-ing, transportation and smelting. During the past 50 years the Utah mining industry has been successively suc-cessively forced to the production of lower grade ores and successively success-ively has faced increasing costs inherent in deeper work. With no increase in the market value for its products, changes in mining methods, meth-ods, milling practice, and smelting practice have been necessary for survival. The American Smelting and Refining Company, well aware of this from its past experience, is constantly endeavoring to improve its smelting practice. |
