Laterite Sulfate Ripening Roasting - Flooding Leach Solution Recovery Of Nickel And Cobalt And Other Valuable Metals Research

With the depletion of the nickel and cobalt contained sulfide ore which is easy treated by pyrometallurgical processes, more attentions have been paid on the treating of nickel laterite by hydrometallurgical processes. After different leaching processes, the leaching solution is obtained which contains nickel, cobalt, manganese, iron, chromium, aluminum and other metals in the form of metal salts. To recover the valuable metals like nickel and cobalt, a reasonable and economical method to separate the impurities and purify the leaching solution has a great significance for the whole treating processes of nickel laterite.In this research, a mixed metal ions solution was treated which was obtained from Philippines nickel laterite using concentrated sulfuric acid curing-roasting-leaching processes. By analyzing the constitution of the leaching solution, results showed that there have a high content of Fe3+,Al3+and Mn2+ions in the solution while the content of Cr3+,Zn2+,Cu2+,Ca2+,Mg2+ ions and other impurities was realitivily low. For the complex composition of the solution, a four-step precipitataion mehod was taken by comparing different methods, including the remove of Fe3+, Al3+ and Cr3+ ions by hydrolysis co-precipitation, remove of Ca2+ and Mg2+ ions by fluoride precipitation, remove of Zn2+and Cu2+ ions by sulfide precipitation and the remove of Mn2+ions by oxidation precipitation. After the precipitation and separation of impurities, a pure solution which contained Ni2+ and Co2+ ions and little impurities was obtained.By adoption of single factor experiments, optimum technical conditions were determined while the optimumexperiment results wereobtained. Using hydrolysis precipitation mehod to remove Fe3+,Al3+and Cr3+ ions, under optimum conditions, the removal rate were 99.6%,99.4% and 92.2%,respectivelly. Remained concentration of Fe3+,Al3+ and Cr3+ ions in the solution were lower than0.05g/L,0.03 g/L and 0.04 g/L, respectively. By utilizing fluoride precipitation method to remove Ca2+ and Mg2+ ions, precipitation rate of Ca2+ and Mg2+ can reach88.91% and 93.07%, remained concentration of Ca2+ and Mg2+ ions in the solution can be recuced to 0.03g/L and 0.07g/L. Using sulfide precipitation method to remove Zn2+and Cu2+ ions,99.9% of Cu2+ and 99.5% of Zn+ can be precipitated and separated from the solution, remained concentration of Zn2+and Cu2+ ions were lower than 0.002g/L and 0.001g/L. Oxidation precipitation method was adopted to remove Mn2+ ions in the solution at last. Precipitaion rate of Mn2+ was higher than 99.9%, remained concentration of Mn2+ in the solution was lower than 0.004g/L. After the precipitation and separation processes, the solution which contained Ni2+ and Co2+ ions and trace impurities was ontained. Through the entire processes, more than 90% of nickel and 85% of cobalt can be recoverd from the solution.According to the characteristics of the materials, the present work determined the optimum technical conditions for each process,which will contribute a techincal scheme to the industrialized practice and production.