螯合沉淀法去除稀土冶炼废水中的重金属试验研究

Removal of Heavy Metals from Rare Earth Hydrometallurgical Wastewater by Chelating Precipitation Method

研究了采用螯合沉淀法从稀土冶炼废水中去除铅、锌、镉等重金属,筛选了重金属螯合剂,并通过单因素和正交试验确定了影响重金属去除的主要因素及最佳工艺条件。结果表明:以二甲基二硫代氨基甲酸钠(福美钠)为螯合剂能有效去除稀土冶炼废水中的总铅、总锌、总镉;螯合剂用量对重金属去除率的影响最大,搅拌速度次之,反应时间、废水pH的影响较小;在废水pH=9.5、反应时间15 min、福美钠加入量30 mg/L、搅拌速度180 r/min条件下,经螯合沉淀处理的出水中ρ(∑Pb)<0.2 mg/L、ρ(∑Zn)<1.0 mg/L、ρ(∑Cd)<0.05 mg/L,符合排放标准要求。

The removal of heavy metals such as lead,zinc and cadmium from rare earth hydrometallurgical wastewater by chelating precipitation method was studied,and the chelating agents of heavy metals were screened.The main factors and the optimum process conditions were determined by single factor test and orthogonal test.The results show that the total lead,total zinc and total cadmium in rare earth hydrometallurgical wastewater can be effectively removed by using sodium dimethyl dithiocarbamate as a chelating agent.The dosage of chelating agent has the greatest effect on the removal rate of heavy metals,followed by stirring intensity,reaction time and pH of wastewater.Under the conditions of wastewater pH=9.5,reaction time of 15 min,the dosage of sodium dimethyl dithiocarbamate of 30 mg/L,stirring speed of 180 r/min,the effluentρ(∑Pb)<0.2 mg/L,ρ(∑Zn)<1.0 mg/L,ρ(∑Cd)<0.05 mg/L after chelating precipitation treatment,which can meet the requirements of emission standard.