浓缩灰酸洗液中重金属脱除技术研究

Research on Heavy Metal Removal Technology of Concentrated Ash Acid Wash Solution

以浓缩灰为研究对象,采用HCl为酸洗浸提剂,将重金属洗脱到酸洗液中,研究了3种重金属沉淀剂:片碱(NaOH)、30%NaOH溶液和Na_(2)CO_(3)粉末对酸洗液中Zn、Pb、Cu、Cd沉淀脱除效果的影响。结果表明:在pH为7~9时,3种重金属沉淀剂对4种重金属的沉淀脱除率均随pH增大呈增加趋势,且NaOH类沉淀剂对重金属的沉淀脱除效果远高于Na_(2)CO_(3)类沉淀剂;在pH>9时,其脱除率增长趋势变缓或略有下降。其中,Na_(2)CO_(3)粉末、30%NaOH溶液、片碱(NaOH)分别在pH为9、10、10时,对4种重金属的综合脱除效率达到峰值,分别为97.95%、98.71%、99.41%。3种沉淀剂对重金属的脱除效果差别不大,但综合考虑成本、运输、储存及投料等工程应用价值及安全生产方面,采用片碱(NaOH)作为重金属沉淀剂,调节反应溶液pH为10时,对浓缩灰酸洗液中重金属的脱除效果最佳,最适于工程应用。

The concentrated ash was taken as the research object,HCl was used as the acid washing leaching agent to elute heavy metals into the acid washing solution.The effects of three heavy metal precipitators of flake alkali(NaOH),30%NaOH solution,and Na_(2)CO_(3)powder on the precipitation and recovery of Zn,Pb,Cu,and Cd in the acid washing solution were studied.The results showed that at pH 7~9,there was an increasing trend with the increase of pH,and the precipitation removal efficiency of NaOH type precipitants for heavy metals was much higher than that of Na_(2)CO_(3)type precipitants;when pH>9,the growth trend of its removal rate became slow or slightly decreased.Among them,when the pH of flake alkali(NaOH),30%NaOH solution,and Na_(2)CO_(3)powder were 9,10 and 10,the removal efficiency of the four heavy metals reached the peak,which were 97.95%,98.71%and 99.41%,respectively.The removal efficiency of heavy metals by the three types of precipitants was not significantly different,but considering the engineering application value of cost,transportation,storage,and feeding,as well as safety production,flake alkali(NaOH)was used as a heavy metal precipitant.When the pH value of the reaction solution was adjusted to 10,the removal effect of heavy metals in the concentrated lime acid washing solution was the best,which was the most suitable for engineering application.