白钨选矿尾水石灰絮凝沉降效果初步探讨

STUDY ON COAGULATING PRECIPITATION OF LIME FOR DRESSING WASTEWATER OF SCHEELITE ORE

为了利用人工湿地对白钨选矿尾水进行深度处理时不发生堵塞,选择石灰作为絮凝剂,进行了预处理试验,考察了絮凝剂用量对尾水沉降速度及污染物去除效率的影响。结果表明:随着石灰用量的增加,清液中悬浮物和重金属的含量降低,尾水的沉降速度减慢。对比清液中重金属与悬浮物的去除率,并根据原矿成分和选矿流程进一步推导,发现尾水中重金属的主要存在形式为悬浮态。综合考虑沉降速度、清液中悬浮物含量、经济效益三个因素,确定预处理过程中石灰用量为1.5kg/t尾水。

Using constructed wetland to purify dressing wastewater of Scheelite ore can not only make the effluent reach the high emission standard,but also lower the expense. But this wastewater contains large amount of tiny suspended solids which are difficult to sediment,directly pouring into the wetland is easy to cause clog,affecting water flow,which also makes the whole system unable to collect sufficient water,resulting in operation problems,so a chemical pretreatment to reduce suspend solids is necessary. In this study, a chemical pretreatment test was made to investigate how flocculant dosage affect sedimentation rate and pollutant removal efficiency. In the test,lime was used as flocculant. The result showed that with the dosage of lime increased,the amount of suspended solids and heavy metals both decreased,and the sedimentation rate slowed down. Compared with the removal of heavy metals and suspended solids,a conclusion based on the composition and ore dressing progress that the large amount of heavy metal was stay in suspended solid was found. The removal of suspended solids and heavy metals occurred at the same time,the main pollutant in the wastewater was suspended solids. The dosage of lime in chemical pretreatment progress was 1. 5 kg / t considered the factors of sedimentation rate,the amount of suspended solid and economic benefits.