含CO_(2)废气再生高钙废水工艺研究

Study on the Regeneration Process of High Calcium Wastewater by CO_(2) Waste Gas

采用含CO_(2)废气脱除菱镁矿脱钙产生的氯盐废水中的Ca,“以废治废”,协同处理,实现了废水循环利用和废气降碳的目的。结果表明,含CO_(2)废气再生含Ca废水的最佳条件为废气流量与溶液量比0.2((mL_(气)/min)/mL_(液)),废气中CO_(2)含量为33%,沉淀温度为40℃,MgO添加量为1.2倍理论量,沉淀时间4 h,搅拌线速率3.3 m/s;钙沉淀率为99.62%,产生的除钙渣中碳酸钙含量为97.35%,可作为工业碳酸钙产品。此外,除钙后液中Ca∶Mg摩尔比降至0.0033,溶液可以有效循环用于含钙菱镁矿脱钙,社会和经济效益显著。

In this study,the purpose of waste water recycling and waste gas decarburization was realized by using CO_(2) waste gas to remove Ca from chlorine salt wastewater,which produced by magnesite decalcification,"using waste to treat waste" and collaborative treatment.The optimal conditions for regenerating Ca-containing waste water were as follows:the ratio of waste gas flow to solution is 0.2((mL_(gas)/min)/mL_(liquid)),CO_(2) content in waste gas was 33%,precipitation temperature was 40 ℃,MgO addition amount was 1.2 times the theoretical amount,and precipitation time was 4 hours,stirring line speed 3.3 m/s.Under these conditions,the calcium precipitation rate is 99.62%,and the calcium carbonate content in the calcium removal slag is 97.35%,which can be used as industrial calcium carbonate products.In addition,the molar ratio of Ca/Mg in the solution is decreased to 0.003 3 after calcium removal,and the solution can be effectively recycled for the decalcification of calcium-containing magnesite,which has significant social and economic benefits.