Research On The Step-by-step Separation And Enrichment Of Cobalt From Cobalt Slag Purified By Organic Matter In Zinc Hydrometallurgy

Cobalt metal is listed as a key strategic resource by many countries.my country's cobalt ore resources are poor and the degree of external dependence is high.A large amount of organic matter purification cobalt slag produced by hydro-zinc smelting enterprises every year,the comprehensive recovery of cobalt is of great significance.In this paper,the organic matter purification cobalt slag of hydro-zinc smelting enterprises is used as raw material to develop a low-acid leaching-calcining-reductive leaching-oxidation precipitation process for the gradual separation and enrichment of cobalt from organic cobalt slag.The law of phase inversion and the behavior trend of other valuable metals are explored.The main research content and conclusions are as follows:(1)The primary separation of zinc,cadmium and other metal elements from cobalt in the cobalt slag is achieved by low-acid leaching of the cobalt slag.The removal rate of zinc in comprehensive conditions experiment can reach 89.70%,and the enrichment ratio of cobalt in the leaching residue increases from 5.45%to 8.17%;the low-acid leaching countercurrent cycle experiment has determined that the optimal number of cycles for the enrichment of the leaching solution is 3 times,and the Zn²⁺in the leaching solution the concentration is 49.96g/L.(2)The theoretical calcination temperature is 400?obtained by thermogravimetric analysis of low acid leaching cobalt slag.The cobalt-containing phases in the slag are mainly CoSO₄.6H₂O and Co₃S₄,but due to the existence of Co₃S₄,the cobalt leaching rate in the slag is only 70.97%.The calcination temperature test was carried out at different temperatures.The main cobalt-containing phases in the slag at 500°C were CoSO₄ and Co O,while the main cobalt-containing phases in the slag at600°C were CoSO₄ and Co₃O₄ due to over-oxidation.The leaching of cobalt in the slag at 500°C The rate is 92.84%,the final calcination temperature is selected to be 500?,the calcined slag contains 30.50%cobalt,and the main cobalt-containing phases are Co O and CoSO₄.(3)The technical optimization parameters for the reduction and leaching process of calcined cobalt slag are:the initial sulfuric acid concentration is 60g/L,the initial Na₂SO₃ concentration is 20g/L,the reaction temperature is 80?,the liquid-to-solid ratio is 10:1m L/g,and the reaction time is 2h.Under these conditions,the metal leaching rate was Co 92.84%,and the composition of the obtained leaching solution was Co²⁺28.98g/L.(4)Using sodium persulfate direct oxidation method,hydrogen peroxide direct oxidation method,and hydrogen peroxide indirect oxidation method to study the oxidative precipitation of Co²⁺in the reduced leaching solution,and the efficiency of cobalt precipitation under the condition of p H 1.2 by the direct oxidation method of sodium persulfate It is only 65.57%,and the oxidant Na₂S₂O₈ consumes a large amount;the direct oxidation of hydrogen peroxide cannot directly oxidize and hydrolyze Co²⁺to Co(OH)₃ under the condition of p H 1.2;the precipitation rate of cobalt can be obtained by the indirect oxidation of hydrogen peroxide.Reach 94.2%,and then pickling the precipitated residue with a dilute H₂SO₄ solution of p H 1 to obtain a Co(OH)₃ residue containing 51.74%cobalt,which provides a high-quality raw material for further cobalt extraction.(5)The step-by-step separation and enrichment process of cobalt slag for organic purification developed by this research has realized the efficient enrichment of cobalt.From the raw cobalt slag to the final product Co(OH)₃,the cobalt element is enriched by 9.5 times.The comprehensive recovery rate of cobalt is 87.42%.At the same time,this process uses H₂O₂ in the oxidation precipitation stage of Co²⁺to replace the conventional Na₂S₂O₈ with huge consumption as the oxidant,reducing the process cost,and the final product Co(OH)₃ obtained provides high-quality raw materials for further extraction of cobalt.