| Copper smelting dust is a waste generated during the pyrometallurgical process of copper,which contains various valuable metal elements such as copper,lead,zinc,and other harmful elements such as arsenic.With the continuous development of the copper smelting industry,the reserves of arsenic containing dust are also increasing.Currently,most of the current researches mainly focus on the alkali process of Na OH+Na2S.However,the traditional alkali leaching process has the following problems:First,Long separation and recovery process for valuable metals such as copper,lead,and zinc,Second,Excessive addition of Na2S leads to a high content of calcium sulfide in subsequent calcium salt arsenic slag,which can cause secondary pollution due to long-term storage.In response to the above problems,this paper proposes an oxidation alkali leaching sulfuration precipitation distribution treatment process.Recovery of copper in the form of Cu（OH）2 through oxidation alkali leaching.This process realizes the step-by-step recovery of copper,lead,and zinc.Arsenic,lead,and zinc are fed into the liquid,and then lead and zinc are separated and recovered through sulfuration precipitation.Arsenic containing solution undergoes calcification precipitation and carbothermal reduction,resulting in high purity of arsenicα-As form realizes recycling.The main research conclusions are as follows:（1）It was determined that copper,lead,zinc,and other metal elements in high arsenic copper smelting dust mainly exist in the form of sulfate,while arsenic existed in the form of arsenic trioxide.The optimal conditions of oxidative alkali leaching were:Na OH concentration of 3.5 mol/L,leaching temperature of 90℃,leaching time of 60min,rotational speed of 300 r/min,and liquid-solid ratio of 8:1.The amount of H2O2added is 1.2 times that of H2O2/As2O3.Under the optimal conditions,the leaching rates of As,Pb,Zn,and Cu are 99.27%,82.82%,95.60%,and 1.78%,respectively.The leaching residue mainly was existed in the form of Cu（OH）2.Kinetic studies had shown that the apparent activation energies of arsenic,lead,and zinc during the oxidation alkali leaching process are 6.73 k J/mol,4 k J/mol,and 4.94 k J/mol,respectively.The leaching process is all controlled by diffusion.（2）Using the equilibrium relationship of various substances in As（Ⅴ）-S-H2O system and As（Ⅲ）-S-H2O system,through thermodynamic calculations,it were compared that the size of[S]/[S]T in As（Ⅴ）-S-H2O system and As（Ⅲ）-S-H2O system with S/As of 1,2,3,and 4,respectively,and p H range between 8-14.The results showed that As（Ⅴ）had a weaker binding ability with sulfur ions in solution than As（Ⅲ）,resulting in less formation of thioarsenate ions.（3）The experimental study on sulfide precipitation of oxidizing alkali leaching solution mainly investigated the effects of Na2S addition,reaction temperature,and reaction time on the precipitation rates of lead and zinc.The optimal conditions were as follows:the amount of Na2S added was 1.2 times,the reaction time was 60 min,and the reaction temperature was 50℃.Under the optimal process conditions,the precipitation rates of lead and zinc are 99.78%and 99.5%,respectively.The main components of sulfide slag are lead sulfide and zinc sulfide.（4）In this paper,the method of calcification precipitation and carbothermal reduction is used to treat arsenic in the sulfurized liquid with high value.Comparing the commonly used methods of"Na2S+Na OH"treatment of copper smelting dust,the results show that the oxidation alkali leaching sulfide precipitation distribution treatment process used in this article can reduce the residual amount of S in the subsequent process to only 0.95%.Calcification arsenic precipitation and carbothermal reduction can obtain elemental arsenic,and there will be no enrichment of Ca S in the reduction slag,avoiding the risk of H2S generation during subsequent recycling of the reduction slag. |
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