垃圾焚烧飞灰与玻璃添加剂熔融固化物相转变研究

Phase transitions of MSWI fly ash and glass additives during vitrification

高温熔融固化城镇生活垃圾焚烧飞灰是一类极具前景的危险废物处理技术。在熔融固化过程中飞灰和玻璃添加剂反应引起的物相转变一直是该领域关注的重点。以飞灰和配合料(飞灰和玻璃添加剂混合物)为研究对象,利用ICP-AES、IC、DSC和XRD等表征方法确定飞灰化学组成,并开展高温熔融过程中的物相转变研究。结果表明,焚烧飞灰主要由Ca、Si、Cl组成,物相主要包括含水化合物、氯化物、碳酸盐和硫酸盐等。飞灰在热处理过程中主要发生含水化合物脱水分解、碳酸盐分解及硅酸盐中间物相生成;引入玻璃添加剂(SiO_(2)和B_(2)O_(3))后,配合料的脱水和碳酸盐分解反应基本不受影响,但硅酸盐中间物相的析出温度降低,并在850℃出现玻璃相,最终在1300℃完全转变为非晶态;此外,延长保温时间在一定程度上可以促进物料间的反应。

Vitrification of municipal solid waste incineration(MSWI)fly ash is a promising technology to treat hazardous wastes.The feed-to-glass conversion during the melting solidification process has been of great concern.Phase transformations of fly ash and the feed(the mixture of fly ash and glass additive)at elevated temperature were analyzed with ICP-AES,IC,DSC and XRD.The results show that the fly ash is mainly composed of Ca,Si,and Cl,and the crystalline phases mainly include hydrous compounds,chlorides,carbonates,and sulfates.Fly ash occurs dehydration of hydroxides,decomposition of carbonates and formation of silicate intermediate phases as the temperatures increased.After included glass additives(SiO_(2)and B_(2)O_(3)),the reactions of dehydration and decarbonation could hardly be affected,while the formation of intermediate silicate phases occurs in the lower temperature and the amorphous phase starts to appear in the feed at 850℃.The feed finally turns to molten glass at 1300℃.Additionally,prolonging the heat-treatment time could promote feed reactions.