Study On The Novel Process Of Selective Extraction Of Copper And Cobalt From Heterogenite

Cobalt, as an important strategic metal resource, is used as an important raw material in the production of a variety of high temperature corrosion-resistant alloys, tungsten carbides, superhard materials, magnetic materials and catalysts, et al. Copper is a kind of non-ferrous metals closely related to human beings, which is widely applied in electric, light industry, machinery manufacturing, construction and defense industry. However, cobalt and copper resources in China are in deficiency, especially the cobalt resource, the majority of which is in the form of heterogenite, imported from Africa, the Democratic Republic of the Congo (DRC). Up to now, there are many problems exist in the treatment of heterogenite, such as the complex equipment, low metal recovery, low comprehensive utilization, long technical process and huge ammonium-containing waste water discharge, et al. In this paper, the heterogenite with high copper content from DRC was used as the raw materials, while, the research on the new technology of reductive acid leaching-selective extraction of copper and cobalt by cyclone electrowinning was conducted. The process was in short flowsheet with simple equipment and environmental friendly without waste water discharge.In this paper, the occurance statements of the main metals in the ore was investigated, combined with the thermodynamic analysis, the reductive leaching process was determined for the extractive leaching of copper and cobalt. The results show that the cobalt and copper recovery reached98.13%and98.54%, respectively, while the iron leaching efficiency was only0.39%under the conditions as sulfuric acid of75g/L, Na2SO3dosage of7%, liquid to solid ratio of4:1, leaching time of0.5h at70℃. The copper and cobalt was simultaneously recovered in the leaching process, which ensured the valuable metal recovery being leached into the leaching liquor while the iron was left in the residue, thus, the iron removal process could be omitted and the leachate was used for the selective extraction of copper and cobalt by cyclone electrolysis.Investigations on the extraction of copper from the leachate obtained from the reductive acid leaching by two-stage cyclone electrowinning in sequence were conducted. In the first stage, the circular flow of the electrolyte was determined as400L/h, current density as360A/m2, the temperature of the electrolyte as20℃and the terminal concentration of the copper ion as2.9～3.Og/L, the copper so obtained could meet the national standard GB/T467-1997and the cathodic current efficiency reached97.73%. In the second stage, the circular flow of the electrolyte was determined as600L/h, the current density as480A/m2, the temperature of the electrolyte as40℃and the concentration of the copper ion as0.01g/L, the crude copper obtained was with99.23%copper content and the cathodic current efficiency was65.89%. Besides, the extraction of cobalt from the liquor after copper removal by cyclone electrowinning was conducted, the pH value of the solution was controlled at the range of2.8～3.3, the circular flow of the electrolyte as600L/h, the current density as480A/m, the temperature of the electrolyte as55～60℉, the boric acid content as6g/L, the dosage of the addictive A as1.75g/L and the terminal concentration of the cobalt ion as around0.5g/L, the cobalt obtained could meet the national standard GB/TCo9995and the cathodic current efficiency reached95.5%. The liquor after cobalt removal could reused in the reductive acid leaching, therefore, the liquor in the system could realize the closed circulating. The yield of the copper and cobalt reached98.23%and94.55%, respectively.