Iron Removal And Separation Of Cobalt And Nickel Using A Synergistic Extraction System From The Bio-leaching Solution Of Low-grade Sulfide Of Nickel And Cobalt

Iron is the key impurity ion in the complex bio-leaching solution during the purification separation process. Iron was precipitated by the formation of jarosite or goethite. And sulfide precipitation or extraction of nickel and cobalt at high pH were used in the hydrometallurgy at home and abroad. But this does not apply to bio-leaching solution at room temperature and the low pH. Therefore, the development of removal of the iron and the subsequent separation of nickel and cobalt process at room temperature and low pH is particularly necessary. This can provide a new way for the purification of the iron and separation of nickel and cobalt by synergistic extraction in the bio-leaching solution.According to the instance that the content of the iron and other impurities are high whereas the content of the valuable metals is low in the bio-leaching solution of low-grade sulfide of copper, nickel and cobalt from Jilin Baishan. Process of the iron removal by formation of jarosite and separation of the nickel and cobalt by synergistic extraction were investigated. And related mechanism was studied.The studies of the iron removal shown that in the stage of bacterial oxidation, ferrous was oxidized completely after36hours in the pH range of1.4-2.0and temperature range of30～40℃; In the process of iron removal by the formation of jarosite, the iron removal rate was above99.9%at pH of2.0, temperature of45℃The primary and secondary factors that affect the jarosite precipitation was confirmed as time, inoculate quantity and the concentration of iron.The thermodynamics study of the iron removal process shown that the jarosite can exist stably at the pH range of0.80-2.76at the temperature of45℃. Dynamic process research shown that the iron removal process can be promoted by increasing the concentration of iron, pH value and temperature.The studies of separation and recovery of the nickel and cobalt from bio-leaching solution using synergistic extraction of P507and Cyanex272shown that the best condition for separation the divalent nickel and cobalt ions using synergistic extraction is:the saponification rate of organic phase is50%and saponification time is30minutes; The composition of the organic phase is10%[P507:Cyanex272(volume ratio3:2)]+85%sulphonated kerosene+5%TBP. The water and organic ratio is3to1and the initial pH is2.5. In these conditions, the extraction rate for divalent cobalt ion is92.96%. The separation of divalent nickel and cobalt ions was realized under the low initial pH.Separation of industrial copper nickel and cobalt bio-leaching solution shown that the iron removal and separation of the nickel and cobalt from the bio-leaching solution was realized through the process of the efficient extraction of copper using the M5774, the iron removal at the low temperature, the impurities elimination completely with P204, and the separation and of the nickel and cobalt by synergistic extraction with P507-Cyanex272system at the low pH value.