Separation and solidlfication of arsenic in copper slag containing arsenic
Arsenic(As)is a harmful impurity element in the zinc(Zn)smelting process,which not only restricts the smooth and safe production of Zn smelting,but also affects the economic benefits of enterprises.A Zn smelting enterprise in Yunnan province,the"SO2 reduction leaching-iron powder Cu precipitation"process was adopted to treat Zn smelting leaching residue,resulting in the As enrich in the Cu As residue.In order to reduce As content and improve the pricing coefficient of the residue,the Cu post-sedimentation liquid,obtained from"SO2 reduction leaching-iron powder Cu precipitation"process,was used as the leaching agent.The As-containing Cu residue was mixed with the Cu post-sedimentation liquid at at a certain liquid-solid ratio,which containing a certain concentration of H2SO4 and Fe2+.And then,the mixed material was treat by oxygen pressure leaching process to carry out the separation and solidification of As.The effects of key technical parameters on the leaching efficiency of Cu and As in arsenic-containing Cu residue,the As solidification efficiency,and the quality of arsenic-fixing residue were investigated.Results show that the leaching efficiency of Cu and As are more than 99％under the optimal process parameters at initial sulfuric acid concentration of 50 g/L,liquid-solid ratio of 5∶1,oxygen partial pressure of 0.4 MPa,leaching temperature of 120 ℃,and leaching time of 3 h.The As-containing Cu residue was treated with arsenic-fixing process under the conditions of iron-arsenic mass ratio of 2.0,initial pH value of 1.0,liquid-solid ratio of 5∶1,oxygen partial pressure of 0.4 MPa,reaction temperature of 120 ℃,and reaction time of 3 h.The loss of valuable metals is small,and As is solidified in a stable scorodite crystal.The As solidification efficiency is 98.23％,and the scorodite crystal structure is good,the grain is clear,the surface is smooth,and the edge is neat.The solution after As fixation is cemented by zinc powder to remove Cu,and Cu content of more than 70％in residue can be obtained.After As removal,the pricing coefficient of Cu in the residue increase to 13％.It not only realizes the separation and solidification of As in the Cu residue,reduces the pollution of As to the environment,but also realizes the economic benefits of the Zn smelting enterprise.The research results can provide reference for the high-value utilization of As-containing Cu residue in zinc smelting process and the prevention and control of environmental pollution and environmental risk of As.
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