超细化拜耳赤泥制备PAFC及其絮凝效果评价

Synthesis of PAFC based on the ultra-fining bayer red mud and the flocculation effectassessment

为了探讨工业废渣——拜耳赤泥的综合利用新途径,以超细化拜耳法赤泥为原料,用盐酸浸取的方法将赤泥中的铝和铁溶出,并经聚合制备高效絮凝剂聚合氯化铝铁(Polymeric Aluminum Ferric Chlo-ride,PAFC),对制备聚合氯化铝铁的酸浸工艺参数和絮凝效果进行研究和评价。结果表明,酸浸的最优工艺参数分别为:盐酸浓度6mol/L,液固比5mL/g,反应温度90℃,反应时间1.5 h。在浊度的去除上,自制PAFC与市售PAC、PFC对综合污水有相当或更优的去除效果,最高去除率为66.9%;在COD的去除上,自制PAFC的去除效果介于市售PAC及PFC之间,最高去除率为52.1%;在总磷和磷酸盐的去除上,自制PAFC稍逊于市售PAC、PFC,最高去除率分别为73.8%和77.7%。

The present paper intends to provide a new way for comprehensive utilization of an industrial waste-bayer red mud and a new method for synthesizing PAFC. Thus the author would like to contribute a new technique to the research area for preparing highly-efficient flocculent-polymeric aluminum ferric chloride （PAFC）by using ultra-refining bayer red mud as raw material. As is known, bayer red mud is a kind of waste from aluminum-making industry containing rich Fe and Al. When used as a raw material for synthesizing flocculent, it would bring about a lot of environmental and economic benefits. The actual method for successful synthesizing of the so-called flocculent can be done in the following way： when roasted at the temperature of 650℃ for 4 h in the muffle furnace, bayer red mud can be ground by using a mortar into 300-mesh-pass particles, whose size are about 48 μm. Then it would be possible to use hydrochloric acid for leaching aluminum and iron content out into the ultra-fining bayer red mud. And, the final product PAFC can be prepared through polymerizing procession via the pH adjustment. The author has also carefully studied and developed the best acid leaching conditions and the flocculation results, which can be shown as follows： （1） The best acid leaching conditions are： the concentration of hydrochloric acid should be 6 mol/L, whereas the liquid-solid ratio should be 5 mL/g, with the appropriate temperature being 90℃ and the processing period being 1.5 h. （2）On removing the turbidity, the effect of PAFC should be equivalent or better than the commercially available PAC and PFC. That is to say, the best removal rate should be 66.9%. However, on removing COD, the effect of PAFC should be better than commercially available PAC but worse than PFC, with the best removal rate being 52.1%. Nevertheless, on removing the total phosphorus and total phosphate, the effects of PAFC should be minor than the other two flocculates PAC and PFC. That is to say, the best removing rate should be 73.8% and 73.7%, respectively. Thus, it can be seen that this study has developed a new way for comprehensive utilization of bayer red mud.