High-speed Rail Biological Heap Leach Recovery Of Copper New Technology

Copper can be extracted from a low-grade copper ore by means of microbiological leaching. In the leaching process, copper and the impurities such as Fe was leached and enriched gradually due to the acid in solution. When the Fe3+ content accumulated to a certain amount would jeopardize the normal leaching process. Bio-heap leaching solution containing high iron was treated by mechanically activated pyrite and sodium thiosulfate. After that, copper sulphate was recycled.Mechanically activated pyrite was employed to treat bio-heap leaching solution containing high iron. The precipitation rate of copper and reduction rate of Fe3+ were up to 11.6% and 76.4% under the conditions of reaction temperature at 80℃, mechanically activation pyrite for 3h and 6:1 of liquid to solid ratio, respectively.Sodium thiosulfate was used to treat bio-heap leaching solution containing high iron. When the content of Cu2+, total Fe and Fe3+w as 7.41 g·L-1,27.9 g·L-1 and 14.68 g·L-1, respectively, the reduction rate of Fe3+ and precipitation rate of iron and copper achieved 99.69%,17.52% and 99.96% at 80℃for 60 min with 18 g·L-1 of the amount of Sodium thiosulfate. After treatment, the Cu, S and Fe content of the precipitated residues obtained was 46.61%,27.85% and 3.23%, respectively and the main phase was confirmed to CuS and S.Concentrated sulfuric acid and hydrogen peroxide were added into the precipitated residues obtained from bio-heap leaching solution containing high iron by Na2S2O3 treatment. As a result, the Cu of the precipitated residues was dissolved into copper sulfate solution and the copper recovery reached 93.1%. The obtained copper sulfate solution was crystallized into copper sulfate pentahydrate and the yield of copper sulfate reached 85.37%. If 10000m3 bio-heap leaching solution containing high iron is treated by sodium thiosulfate every month, the obtained copper sulfate pentahydrate can reach 232.5 t and the direct profits can reach 8.43×105 yuan.Bio-heap leaching solution containing high iron was treated by sodium thiosulfate. As a result, the Fe3+ of bio-heap leaching solution containing high iron was reduced to Fe2+ and its acidity increased and the copper was recovered. Moreover, the obtained solution after sodium thiosulfate treatment returned the bio-leap leaching process, which not only reduced sewage discharge and saved water and sulfate acid required in the leaching process, but also brought good economic and social benefits.