混凝沉淀法处理含砷选矿废水

某钨矿含砷选矿废水砷含量高且砷以As(V)为主要存在形态,采用混凝沉淀法处理,详细考察了生石灰、硫酸亚铁和六水三氯化铁3种混凝剂对废水中砷的去除效果。实验结果表明,在PAM投加量40 mg/L,静沉时间60 min条件下,比较分析3种混凝剂对砷的去除效果,三氯化铁为最佳除砷混凝剂。三氯化铁最佳除砷工艺条件为:pH 7.5,三氯化铁投加量986.67 mg/L,混凝反应时间25 min,PAM投加量为40 mg/L,静沉60 min,含砷选矿废水经该工艺处理后,砷去除率可达99.14%,出水砷浓度降至0.361 mg/L,达到国家污水综合排放标准(GB8978-1996)。

Treatment of arsenic-containing mineral processing wastewater by coagulation and sedimentation process

Mineral processing wastewater with high concentration of arsenic mainly in the form of As (V) was obtained from a tungsten mine. Coagulation and sedimentation processes were selected to treat the arsenic-containing mineral processing wastewater, and the effects of lime, ferrous sulfate and ferric chloride on the arsenic removal were investigated in detail. As a result, under the same conditions of sedimentation with polyacrylamide (PAM) dose of 40 mg/L and precipitation time of 60 min, ferric chloride was the optimal removal coagulant in the coagulation of arsenic-containing mineral process wastewater compared to the other two coagulants lime and ferrous sulfate by arsenic removal efficiency. The optimum arsenic removal conditions with ferric chloride were pH 7.5, ferric chloride dose of 986.67 mg/L, coagulation reaction time of 25 min, PAM dose of 40 mg/L, precipitation time of 60 min. By this process, the removal rate of arsenic could reach 99.14% and the concentration of arsenic in effluent water was 0.361 mg/L, which could meet the standard of Integrated Wastewater Discharge Standard (GB8978-1996).