Abstract:When the chloride ion content in the zinc hydrometallurgy system is high, it will cause certain corrosion to equipments and anode plates in the electrolysis process. At the same time, the increase of lead content in the electrolyte will lead to the precipitation of cathode zinc and lead exceeding the standard, thereby reducing the zinc grade rate and affecting the normal production and economic benefits of the enterprise. In this paper, the self-produced copper slag in the process of zinc hydrometallurgy was used to study the dechlorination of neutral leaching solution and electrolytic waste liquid respectively, and the dechlorination slag was washed with alkali to realize the comprehensive utilization of dechlorination slag resources and determine the best process control conditions. The results showed that the optimum conditions for chloride removal from neutral leaching solution were as follows : initial pH value of 1.5, temperature of 55-65℃, reaction time of 2.0h, and the amount of copper slag was 4.0 times of the theoretical amount. Under these conditions, the removal rate of chloride ions was more than 80%. When the amount of sodium hydroxide used for alkali washing of dechlorination slag is 2.0 times of the theoretical value of chloride ion content in dechlorination slag, the chlorine removal rate of alkali washing was about 85%. The optimum control parameters of chlorine removal from electrolytic waste liquid were as follows: temperature 30-40℃, reaction time 1.0h, copper slag dosage 3.0 times of the theoretical amount. Under these conditions, the removal rate of chloride ion can reach more than 80%. When the amount of sodium hydroxide used for alkali washing of dechlorination slag was 2.5 times the theoretical value of chloride ion content in dechlorination slag, the chlorine removal rate of alkali washing reached about 80%.
