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Show FLoiaiiTiii ' GIB IN FAVOR Being Adopted by Principal Copper Companies in the Southwest. j Thft moat notable improvement in the milling procf-ascfl of the largo copper mining fompMiiies in Xew Mexi'-.o an't Arizona i the adoption of flotation, according to ProfwMur Robert H. Lewis of tho ritato S-IjoijI of Mint's of tbu Ij'rii vpi'hiI v nf Utah. rrulVbfor Lewi.-, working" in r.o-npnr;j Uon with tho Salt Lakn Mai ion of the United iStiiton bu-rouu bu-rouu ol ruined, has recently returned from an extondud trip to eoppcr prop-orf prop-orf ii-ft in f Ime statin. IVot'ftHor Louis reports that owing to t he hig"h priee of euppnr tho rom-jtaninH rom-jtaninH a ni operating at l ull capni'itv. -n rly nil the in inn have a sliding H'aln that varies with tbe- market prno of cupper, 'onseijent.ly the minora ai" rneni viiitr nta i rn uin pay and what might almost bo called ft boom spirit pervndos the canip-i. Many minor ehnnges have been introduced in-troduced in the milling methods, but the most notable iinprov nmont is tho adoption adop-tion of flotai ion ' treatment, either in whole or in part, by all the companies. com-panies. With one exception, the mill have been in operation for several yearn and flotation treatment has been added, but as an extension to former methods of concentrating the ores, it not being considered expedient to reconstruct re-construct tho entire mill until the pop-nihilities pop-nihilities of flotation were more f ul I3 determined. The weakness of the present eystem of gravity concentration lies in the inability in-ability of the machines e m p 1 oy ei 1 to make" a high saving on the tiniest part of tho oro, commonly known as ulitiu's. The very finely divided mineral floats off on the water and cannot be eaved by methods utilizing tho difference in specific, gravity .between tho valuable minora aud tho wante of ganguo as a method of separation. When treating an oro by Hie f iota t ion process, the voliiiiKla m 1 n iru t id finlMfil ( n t'l rtftt", Oil tho top of tho water in the machines as a froth that is removed and the mineral recovered. The gangiie or waste sinks to the bottom of the machine, from where it is sent to waste. Generally Gen-erally speaking, the finer the oro is ground the more suitable it becomes for flotation treatment. It is evident that this method is a valuable aid to gravity grav-ity concentration. "In what might be called the present combination treatment, tho coarser mineral is removed by gravity concentration concen-tration and the fine mineral is recovered recov-ered hv flotntion treatment. The 'mill of the Inspiration Consolidated Consoli-dated Copper company at Miami, AH?!., is a notable exception in that only tho flotation process is used. This company com-pany has over 100,000,000 1 tons of 2 nor cent copper ore in its mine, making It one of tho leading copper properties of tho country. The treatment of tho ore is quite simple. It is first crushed to small size, then ground to the required re-quired fineness and geflt to the flotation flota-tion machines, which "ive a " concentrate, concen-trate, M containing nearly all tho valuable valu-able mineral in the ore, and a waste product, or "tailing," that is thrown away. Tho concentrate is smelted and the copper content recovored iu the metallic me-tallic stato. Conservationists m!r decry the fact that only from 00 to Do per cent of the copper in tho ores is recovered by ordinary ordi-nary milling methods, but it should bo remembered that compauies must be financially profitable in order to continue con-tinue oporations. A higher percentage of recovery is possible, but not profitable, profit-able, iu the opinion of Professor Lewis, due to tho largo increase in the size and cost of plant that would be required re-quired to obtain a higher extraction and the comparatively small added saving sav-ing effected. The addition of the flotation process to gravity concentration plants has resulted re-sulted in a profitable increase in the percentage of extraction, sometimes as great as 10 per cent. Since each additional addi-tional saving of I per cent means an increase in output of 12,000 pounds of copper per day considering the production produc-tion of four of the largest companies alone the economic saving to tho country coun-try is seen to be of great value. |