The dissolution of chalcopyrite in ferric sulfate and ferric chloride media
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details have not been adequately resolved. Hence, further studies appear warranted on the leaching of chalcopyrite in ferric ion media. In the present investigation, the recent literature has been surveyed to identify areas of consensus and to define points of controversy. Those doubtful areas were then carefully reexamined experimentally. The results of the present investigation and the discussion of the recent literature data are presented in the body of the paper below. EXPERIMENTAL To avoid any possible problems associated with synthetic material, all the leaching investigations were carried out using carefully sized and cleaned natural chalcopyrite. The bulk of the work was done with chalcopyrite from Messina, Transvaal, South Africa, but confirmatory tests were also done with material from the Temagami Lake Mine, Temagami, Ontario. Selected pieces of high grade ore were dry-ground to -350 mesh and were then cyclosized in 50 g lots into the following fractions: -37 + 29 #m, -29 + 20 #m, -20 + 14 am and -14 + 10/~m. The various fractions were cleaned by repeated passage through a Franz magnetic separator sequentially set to remove impurities both more and less magnetic than CuFeS2. The magnetically cleaned sulfides were subjected to froth flotation at both pH 6 and pH 10.5 to remove middling particles and residual gangue. The cleaned fractions were then carefully recyclosized in 15 g batches to produce the product for leaching. The sized fractions were washed thoroughly with acetone and were finally vacuum dried at room temperature. The Transvaal chalcopyrite concentrates assayed 35.8 pct Cu. 29.0 pct Fe and 33.5 pct S; they contained over 98 pct chalcopyrite with traces of sphalerite, quartz and pyrite. The Temagami chalcopyrite con-
ISSN 0360-214118110611-0371500.7510 9 1981 AMERICAN SOCIETY FOR METALS AND THE METALLURGICAL SOCIETY OF AIME
VOLUME 12B, JUNE 1981--371
sisted of 95 pct chalcopyrite, 3 pct pyrite, 1.5 pct bornite and 0.5 pet sphalerite. Electron microprobe analysis showed both sulfides to be "chalcopyrite" of stoichiometric CuFeS2 composition. Both materials were examined using a Guinier-de Wolff precision focussing X-ray camera and it was established that both were chalcopyrite and not one of the recently discovered similar phases in the Cu-Fe-S s y s t e m : For the leaching tests, 0.780 g of chalcopyrite was added to 2.7 1 of solution in a thermostated water bath. The relative amounts of solution and chalcopyrite were such that the tests were done at approximately constant Fe 3+ concentration, and ferric ion depletion was never a factor. The leaching solutions were automatically sampled and analyzed colorimetrically for copper with a Technicon AutoAnalyzer. The sized fractions were agitated in the leaching bath by a plastic stirrer and protective atmospheres were used to minimize air oxidation. Liquid removed from the leaching vessels, either by sampling or by evaporation, was replaced by a return feed of barren solution or water, respectively. Throughout the paper the various leaching para
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