China Nonferrous Metallurgy

The light sum method is one of the ideal ways to deal with high arsenic copper solution. The existing literature believes that the copper precipitation of arsenic sulfide slag is mainly the sulfide precipitation reaction of As₂S₃ with copper ions. However， the arsenic sulfide slag used in the field contains a large amount of As₂S₅ in addition to As₂S₃. In order to clarify the copper precipitation reaction mechanism of multivalent arsenic sulfide slag， this study used a high arsenic copper leaching solution and arsenic filter cake of an enterprise as raw materials to investigate the effect of factors such as arsenic sulfide dosage， reaction temperature and reaction time on the behavior of copper precipitation and arsenic leaching. The product was characterized and analyzed， and the following main conclusions were obtained. The amount of arsenic sulfide， reaction temperature and reaction time had a great influence on copper precipitation rate， arsenic leaching rate and arsenic content in slag. In general， with the increase of arsenic sulfide dosage， reaction temperature and reaction time， copper precipitation rate and arsenic leaching rate showed an upward trend， and arsenic content in slag showed a downward trend. Under the conditions of arsenic sulfide slag dosage 1. 3 times， reaction temperature 85℃ and reaction time 60 min， the copper deposition rate is more than 99%， and the arsenic content in the slag can reach 14. 64%. It is necessary to continue to extend the reaction time to soak arsenic. When the reaction time is extended to 255 min， the arsenic content in the slag is 4. 05%. The reaction process can be divided into copper precipitation stage and arsenic leaching stage. The copper precipitation stage （15-60 min） is dominated by the copper precipitation reaction of As₂S₃ and As₂S₅ and the copper precipitation reaction of As₂S₃ with sulfuric acid. The reaction kinetics is zero-order reaction， which is the control step of chemical reaction. In the arsenic leaching stage （75-255 min）， the conversion reaction of As₂S₅ to low valence arsenic sulfide and the sulfur generation reaction of As₂S₃ and As₂S₅ are the main reactions. The reaction kinetic model conforms to the Boltzmann model. In the later stage， the arsenic leaching rate changes little， and the arsenic content in the slag changes little. The results of this study complement the existing copper deposition mechanism of arsenic sulfide slag， that is， for multivalent arsenic sulfide slag with high As（V） content， in addition to As（III） participating in the copper deposition reaction， As（V） also participates in the copper deposition reaction， and there is a conversion to low valence arsenic sulfide to continue the copper deposition reaction.