Recovery of copper from iron ores

In this study, the experiments were carried out on two different iron ore samples containing 0.69 % and 2.55 % copper, provided from Keban region in Turkey. In the first part of the study, it was aimed to enrich copper in both ore by flotation method. The enrichment of the iron ores containing copper by flotation method directly was not achieved. Therefore, both ore samples were sulfurized by H2S before flotation. The effects of pH, refreshing and suppressing reagents, amount of H2S, particle size, type and amount of collector on flotation experiments were investigated. In the flotation experiments, the best result was obtained from flotation of 500 g sulfurized ore containing Cu 0.69 %, sized to -100 mesh with 7.0125g H2S(g). Optimum flotation conditions for the ore were found as follows: collector type, diisobutyldithiophosphinate Aero 3418A; amount of collector, 0.5 mL/100 g ore (1%); pH, 9-11; amount of H2S, 7.0125g. Under the optimum conditions copper yield was obtained as 89.96 %. In the second part of study, leaching was conducted onto the ore containing 2.55 % copper by H2SO4 acid, and a variety of parameters such as effect of acid concentration, leaching time, amount of salt, particle size, solid/liquid ratio, SO2(g) and Na2SO3 were investigated to enable pass of copper into the acid solution. First of all, the effect of acid concentration was investigated. Although higher than 97% copper yield was obtained by flotation with 1.5M, 2.0M or 2.5M acid concentrations, it has been accepted that 1M acid concentration is more appropriate economically to minimize acid consumption. Secondly, ratio of K/S was determined. The acid leaching test results were indicated that 98 % of copper extraction was possible under the optimum conditions, which were determined as 1.0 M H2SO4, 20 h leaching time, room temperature, S/L ratio of 1/1.5 and 100 mesh particle size. Thirdly, the ore was split to -100-150 mesh, -150-200 mesh, -200 mesh to investigate the effect of particle size. In general, copper leaching ratio was decreased with decrease in particle size during 30 min leaching. Furthermore, optimum particle size was determined as -100 mesh. In the third part of study, electrolysis was carried out to recover of high purity copper from the pregnant copper solution obtained after sulfuric acid (H2SO4) leaching. The amount of consumed acid of the solution whose copper were removed by electrolysis after leaching were determined by titration and this amount of acid was added to the solution so that its concentration became 1.0M again. The solution was used for a second extraction so that the effect of other salts passed to the solution from the structure of ore by previous leaching on ratio of copper pass was studied. Then, the solution was prepared for a third extraction. While the leaching ratio increased in the second extraction, it decreased in the third one. Finally, it was found that copper was obtained in 99.9% yield by electrolysis. Keywords: Flotation, Copper, Leaching, Electrolysis