高寒地区露天矿矿坑水混凝试验研究

Experimental study on pit water coagulation of open-pit mine in alpine area

为了解决高寒地区露天矿低温矿坑水悬浮物去除效率低、处理成本高等问题,研究了内蒙古某露天矿矿坑水的水量水质,利用粒径分析、Zeta电位表征了悬浮物的微观结构,采用静态混凝试验研究了悬浮物去除效果。结果表明:该露天矿矿坑水水量和水温均呈夏高冬低两极化,全年矿坑水的水温有8个月处于10℃以下,7个月低于4℃;初沉后矿坑水中的悬浮物仍高于15000 mg/L,悬浮物粒径大部分处于0.4~1.5μm且带负电,属于亚微米级颗粒物;室温下最佳的药剂组合为聚合氯化铝(PAC)+阴离子聚丙烯酰胺(APAM),最佳投加量分别为150 mg/L和1 mg/L,最佳混凝沉淀程序为快速混合搅拌(200 r/min)2 min、絮凝搅拌(60 r/min)15 min,静置沉淀15 min;全年以10℃为基准分为常规段(6~9月)和低温段(1~5月和10~12月)加药,由于低温减缓了混凝剂的絮凝反应,低温段加药量同比常规段增加20%~33%;混凝沉淀出水悬浮物和浊度分别小于50 mg/L和10 NTU,达到《煤炭工业污染物排放标准》(GB 20426—2006)中的悬浮物含量限制要求。

In order to solve the problems of low removal efficiency and high treatment cost of suspended solids(SS)in low-temperature pit water of open-pit mine in alpine regions,the water quantity and quality of the mine water from an Inner Mongolia open-pit mine were studied,and the particle size analysis and Zeta potential were used to characterize the microstructure of suspended solids in the mine pit water.Static coagulation experiments wereconducted to study the removal effect of suspended solids.The results showed that the water quantity and temperature of pit water from the studied open-pit mine were both high in summer and low in winter.Additionally,the water temperature of pit water was below 10℃for 8 months in the whole year,and was below 4℃for 7 months.The suspended solids in mine water were more than 15000 mg/L after initial sedimentation,and most of them were in the range of 0.4~1.5μm with negative charge.The best combination at room temperaturewas polyaluminum chloride(PAC)+anionic polyacrylamide(APAM),and the best dosages were 150 mg/L and 1mg/L respectively.The optimal coagulation and sedimentation procedure was rapid mixture stirring(200 r/min)for 2 min,flocculation stirring(60 r/min)for 15 min,and settling for 15 min.As the low temperature reduced the purification effect of coagulants,the whole year could be divided into conventional period(June to September)and low temperature period(January to May and October to December)based on 10℃.The dosage inthe low temperature period was 20%~33%higher than that in the conventional period.After coagulation and sedimentation treatment,the suspended solids and turbidity in the effluent were less than 50 mg/L and 10 NTU,respectively,reaching the effluent standard of emission standard of pollutants for coal industry(GB 20426-2006).