利用粉煤灰和酸性含铝废水制备聚合氯化铝

Preparation of Polyaluminium Chloride(PAC)from Fly Ash and Acidic Wastewater Containing Aluminum

为解决聚合氯化铝（PAC）生产过程中铝矾土价格上涨带来的成本增加的问题,提出了一种工业化生产PAC的方法,即采用粉煤灰部分代替铝矾土,使用酸溶法提铝,并加入助溶剂NaCl.其最佳工艺条件为：固液比1？3（质量/体积）,盐酸浓度20%,加热酸溶时间3 h,助溶剂NaCl的加入量为固体质量的5%,粉煤灰替代率为20%.由此生产所得液体PAC产品的氧化铝含量约9%,pH3.5~3.9,密度约1.2 g/cm3,盐基度约95%,均符合国家标准.此法工艺简单,节约生产成本且可实现活性白土生产过程中产生的酸性含铝废水的再利用.

A new technics for preparing PAC was proposed in this paper in order to meet the challenge of increasing price of bauxite.That is to partly replace the bauxite by fly ash and to aroid its leading by acid solution,while adding NaCl as a cosolvent.The optimum condition is that the ratio of solid to liquid volum is 1︰3,the concentration of HCl is 20 %,the reaction time is 3 h,the concentration of NaCl is 5 %,and the proportion of fly ash is 20 %.The content of aluminum oxide in liquid PAC prepared under this condition is about 9 %,the pH is varied from 3.5 to 3.9,the density is about 1.2 g/cm3,the basicity is about 95 %.The characteristics of PAC produced this way are in full compliance with national standards.This new technique both save cost and can be resued for treactment of acidic wastewater containing aluminum produced in the production of activated clay.