Abstract:Few researches have been made at home and abroad on the process of Cu & As removal from the post reduction solution in zinc hydrometallurgy. The commonly used process at present is Cu precipitation with Fe powder. However, this process is an impurity removal process with the largest consumption of hematite as auxiliary material and the highest cost, moreover, it has such disadvantages as large consumption of Fe powder, incomplete Cu & As precipitation and the Cu & As content in the post-precipitation solution being off standard, etc. In this paper, exploratory tests have been carried out on the process of Cu & As precipitation with hydrogen sulfide by using the post-reduction solution from a smelter in Yunnan Province as feed material, to study the influence of process parameters including hydrogen sulfide dosage, reaction time and temperature, etc. on Cu & As precipitation efficiency. The test results show that only the hydrogen sulfide dosage and the return amount of Cu residue crystal seed have relatively large influence on the Cu & As precipitation efficiency; the hydrogen sulfide dosage needs to be 1.2 times of the theoretical value to start the effective precipitation of Cu & As, and when it’s 1.4 times of the theoretical value, the precipitation efficiency of Cu and As is 99.95% and 98.45% respectively, which can meet the requirement of the acidic solution on Cu and As content; the return of Cu residue crystal seed can improve the Cu & As precipitation efficiency, when the excess coefficient of hydrogen sulfide is 1.2, Cu residue crystal seed of 5g/L is added into the solution, after reaction for 30min, the precipitation efficiency of Cu and As can reach 99.87% and 95.12% respectively. The exploratory tests indicate that the process using hydrogen sulfide to precipitate Cu & As in the post-reduction solution is feasible, its Cu & As precipitation efficiency is much higher than that of the Fe powder Cu precipitation process, thus, it deserves promoted application.
