铅锌尾矿制备水泥熟料及重金属固化特性

摘要

Taking Qiaokou lead-zinc tailings as a kind of main raw materials to produce cement, the burn-ability of raw meal, the heavy metal curing, leaching toxicity and the strength of clinker were studied. The mineral phases and microstructure of cement clinker were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively, and the mass fractions of heavy metals in clinker were analyzed by the method ofICP−AES. The results show that portland cement which is in accordance with GB 175—2007 can be produced under the calcination temperature over 1 350℃ with 15%−16% mass fraction of lead-zinc tailings, the mass fraction of C3S reaches the maximum of 49.2%, and the compressive strength of cement in 28 d is 53.99 MPa. After incorporating the lead-zinc tailings, the mass fraction of f-CaO in clinker is less than 0.5%, and it improves the burn-ability of raw material. The averaged curing degrees of Zn, As, Cd and Pb are 89.76%, 83.62%, 73.20% and 15.19%,respectively. The leaching toxicities of As, Cd, Pb and Zn are far below the national standard of hazardous waste.%以桥口铅锌尾矿为原料制备水泥熟料，主要研究生料的易烧性、熟料的重金属固化、浸出毒性及水泥的强度。利用X线衍射(XRD)和扫描电镜(SEM)分析不同尾矿掺量及煅烧温度下水泥熟料的矿物相和微观结构，用电感耦合等离子体原子发射光谱法(ICP−AES法)分析熟料中重金属的质量分数。研究结果表明：当煅烧温度超过1350℃且加入铅锌尾矿质量分数为15%~16%时，可生产出符合GB 175—2007标准的硅酸盐水泥，其硅酸三钙(C3S)质量分数最高可达49.2%，28 d抗压强度为53.99 MPa；掺入铅锌尾矿，熟料中游离氧化钙(f-CaO)的质量分数低于0.5%，改善了生料的易烧性；在煅烧过程中，重金属Zn，As，Cd和Pb的平均固化率分别为89.76%，83.62%，73.20%和15.19%；熟料Zn，As，Cd和Pb的浸出毒性远低于危险废物的国家标准。