水泥熟料固化重金属Cu^(2+)和Zn^(2+)及水化浸出行为分析

Behavior of Cement Clinker Solidified Heavy Metal Cu^(2+) and Zn^(2+) and Hydration Leaching

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Cu^(2+)和Zn^(2+),文章研究了危废中重金属Cu^(2+)和Zn^(2+)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:Cu^(2+)和Zn^(2+)均改善了熟料易烧性;Cu^(2+)促进了C_(4)AF的生成,同时也促进了C_(3)S晶粒的生长,并固溶在其中;Zn^(2+)与熟料形成新的矿物相Ca_(14)Al_(10)Zn_(6)O_(35)。通过相对分布系数(D)和分配系数(K_(f))说明Cu^(2+)主要分布在硅酸盐相中,硅酸盐相固化Cu^(2+)的能力强于中间相;Zn^(2+)主要分布在中间相中,中间相固化Zn^(2+)的能力强于硅酸盐相。掺量为2.0%的Cu^(2+)和Zn^(2+)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Cu^(2+)和Zn^(2+)在水泥使用过程中不会对环境造成二次污染。

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.Cu^(2+)and Zn^(2+)are included in most hazardous wastes.The solidification performance and distribution of heavy metals of Cu^(2+)and Zn^(2+)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 Cu^(2+)and Zn^(2+)improved clinker burnability.Cu^(2+)promoted the formation of C_(4)AF,and also promoted the growth of C_(3)S grains,then was solidified in C_(3)S.Zn^(2+)would form a new mineral phase of Ca_(14)Al_(10)Zn_(6)O_(35) in clinker.The relative distribution coefficient(D)and the partition coefficient(K_(f))indicate that Cu^(2+)is mainly distributed in silicate phase.The silicate phase has a stronger ability to solidify Cu^(2+)than the interstitial phase.Zn^(2+)is mainly distributed in the interstitial phase,and the ability of the interstitial phase to solidify Zn^(2+)is stronger than that of the silicate phase.When dosage is 2.0%,the maximum leaching concentrations of Cu^(2+)and Zn^(2+)in cement pastes at 7 day are 1.724 mg·L^(-1) and 0.387 mg·L^(-1),respectively.The cement clinker solidified Cu^(2+)and Zn^(2+)would not cause secondary pollution to the environment during the use of cement.