Study On A New Process For Cobalt Compounds From High Cobalt Residue

The high-grade cobalt residue was a kind of by-product containing cobalt produced in the comprehensive utilization of nickel-cobalt slag of purification process in the zinc hydrometallurgy,which contains considerable valuable metals,but its composition was complex and the recovery was difficult,and it was easy to cause heavy metal pollution to the soil and water body if improper storage.In this paper,high-grade cobalt slag was the research object,a new process of comprehensive recovery of zinc and cobalt and other valuable metals such as zinc and cobalt was developed by using all hydrometallurgy process.Cobalt carbonate products were prepared,the value of cobalt in cobalt residue was reflected.Not only the problem of high cobalt residue treatment was solves,but also the cause of environmental pollution and metal loss for the stacking of high-grade cobalt residue.The new process adopts the principle process of controlled potential leaching,one step removal of iron,copper,cadmium,zinc removal under second step and cobalt precipitation.The optimum process conditions were determined through high cobalt residue leaching,impurity removal,separation of zinc and cobalt,and carbonation precipitation.The optimum process conditions were determined as follows: high cobalt residue leaching sulphate concentration was 15%,reaction temperature was 90?,and reaction time was 2 hours,the leaching rate of zinc and cobalt was higher than 99%,the concentration of cobalt in the leaching solution was 10-12g/L,the Co/Mn ratio of solution was higher than 10000,and the selective leaching could be achieved.The initial pH of the iron removal process was 2,the end pH was 4,the iron removal rate was 99%,the remnant iron was 0.1mg/L,the zinc loss rate was 3.6%,the cobalt loss rate was 2.5%,the iron removal rate was high,cobalt loss was little.The replacement of copper and cadmium with zinc powder,the zinc powder amount of addition was 4.5g/L,temperature control between 50-55?,reaction time was 30 min,the replacement of copper and cadmium could achieve the desired effect.The first zinc removal process,NaOH concentration was 5mol/L,reaction temperature was 85?,reaction time was 2 hours,liquid solid ratio was 5:1,zinc separation rate reached 88%.In the second zinc removal process,the initial pH was around 3.0-4.0,the reaction temperature was 60?,and the zinc reagent-B was 9.0g/L,the remnant zinc was reduced to 26mg/L.The precipitates cobalt carbonate with sodium carbonate,the reaction temperature was 85?,the control reaction pH was about 8,and the purity of cobalt carbonate product was more than 98%.The technical and economic analysis was carried out through the expansion test,and the cost of processing slag was about 5841.52 RMB/t.