水泥窑共处置产品中重金属的形态

Heavy Metal Species in Cement Products from Co-Processing Waste in Cement Kilns

通过模拟煅烧掺入重金属化学试剂的水泥生料,制备水泥熟料,进而制取水泥净浆.采用修正的Tessier连续提取法,分别研究了水泥熟料和水泥净浆中各重金属的形态.结果表明:水泥熟料中Ni,As,Cd和Pb几乎不存在可交换态.其中,Cr和Cd主要以酸性醋酸钠溶液提取态存在,分别为71.0%和95.1%;Ni主要分布在酸性盐酸羟胺溶液提取态(65.6%)中,在残渣态中的分布也较多(20.3%);Pb主要分布在硫化物结合态(72.7%)中,与硫形成某种化合物固溶于水泥矿物相中;As的硫化物结合态和酸性醋酸钠溶液提取态质量分数较高,分别为35.1%和51.8%.水泥净浆中各重金属的形态分布与水泥熟料基本一致,表明重金属的主要化学形态分布受水化作用影响不大.

A modified Tessier sequential extraction method was conducted to study the species of heavy metals in clinker and cement paste acquired from a cement calcination simulation of raw materials mixed with heavy metal chemical reagents.The results showed that the contents of exchangeable Ni,As,Cd and Pb were very small in the clinker.Acidified sodium acetate solution in extractable form was the dominant species for Cr and Cd in the clinker,with the percentages in this form 71.0% and 95.1%,respectively.Acidified hydroxylamine hydrochloride in extractable and residual form,accounting for 65.6% and 20.3% of Ni in the clinker,were the first and second dominant species for Ni in the clinker,respectively.72.7% of Pb existed in sulfide-bound form as a solid solutions compound containing sulfur.Arsenic was mainly presented as acidified sodium acetate solution in extractable and sulfide-bound forms;these two forms accounted for 51.8% and 35.1% of As in the clinker,respectively.The species composing of heavy metals in cement paste were found to be similar to those in the clinker.This might indicate that the hydration reaction has little impact on the chemical form of heavy metals.