新型磷酸镁水泥固化挥发型重金属锌的研究

Study on new type magnesium phosphate cement solidification of volatile heavy metal Zn

利用新型磷酸镁水泥对挥发型重金属锌做固化研究。通过测定磷酸镁水泥的抗压强度、Zn^2+的浸出毒性、水化产物的组成,观察固化后水泥表面微观结构,分析了锌在磷酸镁水泥中的赋存状态及化学态,以此来探究新型磷酸镁水泥对重金属锌的固化效果及机理。结果表明:Zn^2+的掺量由0增至4%(质量分数,下同)时,56 d龄期的抗压强度降低了21.9%。当Zn^2+掺量为4%时,1 d龄期的浸出质量浓度达最大值6.6 mg/L。Zn^2+抑制磷酸镁水泥的水化过程,磷酸镁水泥对锌的固化作用包括物理包覆和化学结合。锌主要以Zn2(PO4)(OH)沉淀物质形态被固化在水泥中,Zn^2+经磷酸镁水泥固化后+2价态并未改变。

New type magnesium phosphate cement(MPC) was used to solidificate volatile heavy metal Zn.By measuring the compressive strength,leaching rate of Zn^2+and composition of hydration products,the surface microstructure of solidified cement was observed and the occurrence and chemical states of heavy metal Zn in MPC were analyzed.Then, the solidification effect and mechanism of new type MPC on heavy metal Zn were explored.Results showed that when the doping content(mass fraction) of Zn^2+increased from 0 to 4%,the compressive strength at 56 d decreased by 21.9%.When the doping content of Zn^2+was 4%,the maximum leaching mass concentration reached 6.6 mg/L at 1 d.Zn2+adversely affected the hydration process.The Solidification effects of MPC on Zn included physical coating and chemical binding.Zn existed mainly in form of Zn2(PO4)(OH),and solidified Zn2+didn′t change by MPC.