以城市生活垃圾焚烧飞灰水洗液制备半水硫酸钙晶须

Preparation of hemihydrate calcium sulfate whiskers by washing solution of municipal solid waste incineration fly ash

我国焚烧飞灰年产生量已超过1×10^(7)t,飞灰资源在利用之前需进行水洗预处理,所产生的飞灰水洗液主要含金属成分为NaCl、KCl、CaCl_(2)及其他重金属。本文将半水硫酸钙晶须的制备和飞灰水洗液的处理工艺相结合,采用飞灰水洗液为原料,先通过除杂解毒去除重金属,然后添加硫酸钠及晶型助长剂十六烷基三甲基溴化铵,利用改进常压法制备半水硫酸钙晶须。试验考察了材料配比、沸腾时间、静置时间对半水硫酸钙晶须产品的影响,结果表明,在n(钙离子)∶n(硫酸根离子)=1∶5、沸腾时间1 h、静置保持1.5 h的条件下,Ca^(2+)回收率可达到95.16%,所制备的半水硫酸钙晶须形貌均匀,长度为30~100μm,直径为2~7μm,长径比可达40,晶须密度大,能够满足硫酸钙晶须标准(DB43/T 1155—2016)中半水硫酸钙晶须的成分要求。本工艺生产成本低廉,环境友好,易于工业化生产,为飞灰水洗液的处理及资源化利用提供了一种新的解决路径。

The annual production of incineration fly ash in China has exceeded 1×10^(7)t.Before utilization of fly ash resources,it needs to washing.The main metal components of fly ash washing solution are NaCl,KCl,CaCl_(2)and other heavy metals.In this paper,hemihydrate calcium sulfate whiskers were prepared by adding sodium sulfate and crystal growth agent cetyltrimethylammonium bromide by removing impurities,detoxification and removing heavy metals from ash washing solution.The process combines the preparation of calcium sulfate hemihydrate whiskers and the treatment process of fly ash washing liquid by using an improved atmospheric pressure method.The effects of material ratio,boiling time and settling time on hemihydrate calcium sulfate whisker products were investigated.The results show that the recovery rate of Ca^(2+)can reach 95.16%under the conditions of n(calcium ion):n(sulfate ion)=1:5,boiling time 1 h and settling for 1.5 h;the prepared hemihydrate calcium sulfate whiskers can meet the composition requirements of hemihydrate calcium sulfate whiskers in the standard of calcium sulfate whiskers(DB43/T 1155-2016),and the products are uniform in appearance,with a length of 30~100μm,a diameter of 2~7μm,an aspect ratio up to 40,and a high density of whiskers.The process has the advantages of low production cost,environmental friendliness and easy industrial production,which provides a new solution for treatment and resource utilization of fly ash washing liquid.