Leaching of Bornite With Oxygen and Ferric Chloride as Oxidants.
NTIS: PB/83-234997 :183 pages
Natural bornite (cu5fes4) leached in ferric chloride or in sulfuric or hydrochloric acid solutions with oxygen showed several differences. In ferric chloride 80% of the copper was leached in two stages. The first was controlled by liquid ferric ion diffusion and chemical surface reaction and required 1 minute for a 30% copper removal. The second was controlled by formation of a surface sulfur layer and then diffusion through the sulfur. With oxygen in sulfuric acid, reaction was slow and only the first stage was studied. Copper removal had an induction period. The bornite structure disappeared at 12% copper removal (also found with ferric chloride) and covellite formed on the surface with a species inside the particles with an x-ray structure similar to cufes2 but with cu3fes4 composition and ferric chloride. Copper removal was controlled by iron dissolution. Surface iron vacancies filled with cu+ to give cus while interior copper dissolution produced cu3fes4. Preliminary results with oxygen and hydrochloric acid showed 80% copper removal and sulfur as end products.
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University of Utah