Behavior of Leaching and Precipitation of Copper and Iron in the Leaching Process of Hydrometallurgy Zinc
This study focuses on the problem of low copper recovery rate in the traditional technology of hydro-metallurgy zinc,the leaching and precipitation behavior of copper and iron,and phase transformations are studied to reveal the reason for restricting copper leaching.The results showed that the copper minerals in the zinc-roasted ore are mainly free cupric oxide and cupric oxide in combination,with a small amount of native and sec-ondary cupric sulfide.In the leaching process,as the pH value gradually increases,the Fe3+is first hydrolyzed and precipitated,and the reducing substances in calcine lead to the reduction and precipitation of copper.When the pH reaches 4.63,copper ions hydrolyze extensively,which causes the content of copper in the residue to in-crease.The reducing substances existing in the system like sulfides have a significant impact on Cu2+,which leads to the reduction and precipitation of Cu2+.The oxidizing system can inhibit the influence of reducing sub-stances on Cu2+in the solution and inhibit the formation of secondary copper sulfide phases.Based on the re-search,a new technical process of zinc calcine direct weak acid leaching of copper and iron,solution neutraliza-tion,and impurity removal was put forward.The leaching rate of copper reached 71.83%and the copper recovery rate was over 70%.The precipitation of copper in the leaching solution can be effectively avoided and the leac-hing rate of copper can be improved by direct weak acid leaching and cementation of copper.
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