以磁性粉煤灰为磁种的磁絮凝沉降研究

Magnetic Flocculation Using Magnetic Coal Fly Ash as Magnetic Seeds

摘要: 为降低成本、提升磁絮凝效果，对粉煤灰磁珠进行球磨加工，并以其为磁种材料对高浊度矿物污水进行磁絮凝沉降处理。以CaCl₂和APAM分别作为凝聚剂和絮凝剂，获得了常规絮凝的工艺参数，进而参照确定了磁絮凝的药剂制度。以球磨后的粉煤灰磁珠为磁种，在250 mT的磁场辅助作用下对高浊度矿物污水进行磁絮凝沉降处理。对常规絮凝和磁絮凝的沉降效果进行了对比，研究了磁种添加量、添加方式等关键因素对磁絮凝沉降的影响规律，并获得了最佳工艺参数。结果表明，在磁种添加量为3.2 g/L，磁场250 mT的条件下，磁絮凝沉降速度较常规絮凝提升48%；磁絮凝沉降10 min后上清液透光率达到84.2%，较常规絮凝提高6.7个百分点；最终尾泥体积量减少至42 mL，比普通絮凝提高40%。研究表明，磁絮凝的高效沉降与粉煤灰磁种的凝聚效应及磁吸附桥联作用有关。

Abstract: To reduce the cost and enhance the magnetic flocculation effect, coal-fly-ash magnetic spheres (CMS) are processed by ball milling and used as magnetic seed material for magnetic flocculation and sedimentation treatment of high turbidity mineral wastewater. The process parameters of ordinary flocculation were obtained using CaCl₂ and APAM as coagulant and flocculant, respectively, and then the agent regime of magnetic flocculation was determined with reference. Further, ball-milled CMS were used as the magnetic species for magnetic flocculation and sedimentation of high turbidity mineral wastewater with the assistance of the magnetic field of 250 mT. The settling effect of ordinary flocculation and magnetic flocculation was compared, and the influence of magnetic sphere addition, addition method and other factors on magnetic flocculation settling was studied, and the best process parameters were obtained. The results showed that under the conditions of 3.2 g/L of magnetic sphere addition and 250 mT magnetic field, the settling speed of magnetic flocculation was improved by 48% compared with ordinary flocculation; the transmittance of supernatant reached 84.2% after 10 min of magnetic flocculation, which was 6.7 percentage points higher than ordinary flocculation; the final volume of tailing sludge was reduced to 42 mL, which was 40% higher than ordinary flocculation. It was shown that the efficient settling of magnetic flocculation could be related to the coalescence effect of CMS and the magnetic adsorption bridging effect.