水泥熟料固化重金属Cu2+和Zn2+及水化浸出行为分析

危废处理是当前的热点问题,水泥窑协同处置作为一种有效的处理方式,逐步为社会所接受。多数的危废中包含Cu²⁺和Zn²⁺,文章研究了危废中重金属Cu²⁺和Zn²⁺在水泥熟料中的固化性能和在熟料中的分布,并探讨了重金属在水泥净浆中的浸出行为和环境安全性。通过熟料易烧性X射线衍射(XRD),矿物相分离萃取,浸出实验得出:Cu²⁺和Zn²⁺均改善了熟料易烧性;Cu²⁺促进了C₄AF的生成,同时也促进了C₃S晶粒的生长,并固溶在其中;Zn²⁺与熟料形成新的矿物相Ca₁₄Al₁₀Zn₆O₃₅。通过相对分布系数(D)和分配系数(K_f)说明Cu²⁺主要分布在硅酸盐相中,硅酸盐相固化Cu²⁺的能力强于中间相;Zn²⁺主要分布在中间相中,中间相固化Zn²⁺的能力强于硅酸盐相。掺量为2.0%的Cu²⁺和Zn²⁺在水泥净浆7 d龄期的浸出浓度最大,分别为1.724和0.387 mg·L^-1。水泥熟料固化Cu²⁺和Zn²⁺在水泥使用过程中不会对环境造成二次污染。

Behavior of Cement Clinker Solidified Heavy Metal Cu2+ and Zn2+ and Hydration Leaching

Hazardous waste treatment is a hot issue at present,and co-processing of cement kilns is an effective treatment method that is gradually accepted by the society.Cu²⁺and Zn²⁺are included in most hazardous wastes.The solidification performance and distribution of heavy metals of Cu²⁺and Zn²⁺in cement clinker are investigated in this work.The leaching behavior of heavy metals in cement paste and environmental safety are researched.Experimental results show that Cu²⁺and Zn²⁺improved clinker burnability.Cu²⁺promoted the formation of C₄AF,and also promoted the growth of C₃S grains,then was solidified in C₃S.Zn²⁺would form a new mineral phase of Ca₁₄Al₁₀Zn₆O₃₅ in clinker.The relative distribution coefficient(D)and the partition coefficient(K_f)indicate that Cu²⁺is mainly distributed in silicate phase.The silicate phase has a stronger ability to solidify Cu²⁺than the interstitial phase.Zn²⁺is mainly distributed in the interstitial phase,and the ability of the interstitial phase to solidify Zn²⁺is stronger than that of the silicate phase.When dosage is 2.0%,the maximum leaching concentrations of Cu²⁺and Zn²⁺in cement pastes at 7 day are 1.724 mg·L^-1 and 0.387 mg·L^-1,respectively.The cement clinker solidified Cu²⁺and Zn²⁺would not cause secondary pollution to the environment during the use of cement.