钼尾矿复合胶凝材料的制备及其水化机理研究

Study on Preparation and Hydration Mechanism of Composite Cementitious Materials using Molybdenum Tailings

为了促进固体废弃物的资源化利用,解决尾矿堆积带来的环境、安全问题,并提供相应的理论依据,以钼尾矿为主要原料制备复合胶凝材料,通过粒度分析、力学性能测试、X射线衍射(XRD)和扫描电镜(SEM)等测试手段,研究了钼尾矿磨矿时间和掺量对胶凝材料性能的影响及复合胶凝材料的水化机理。结果表明:①当钼尾矿粉磨时间为80 min,比表面积为500 m^2/kg,其28 d活性指数接近1.2;钼尾矿掺量为40%,胶砂比为1∶3,水胶比为0.5时,所制备的复合胶凝材料胶砂块28 d抗压强度为52 MPa。②复合胶凝材料水化反应初期,主要生成水化硅酸钙和钙矾石,为胶砂块提供了早期强度,水化反应后期主要产物为C—S—H凝胶、水化铝酸钙及钙矾石(AFt),尾矿残余颗粒及水化产物的凝聚效应为胶砂块强度提供了保障。

The composite cementitious materials were prepared using molybdenum tailings for enhancing the utilization of solid waste resources.In order to solve the environmental and safety problems caused by tailings accumulation,and provide the corresponding theoretical basis,the research focuses on effects of grinding time and contents of molybdenum tailings on properties of cementitious materials and hydration mechanism of composite cementitious materials were conducted by means of particle size analysis,mechanical properties testing,X-ray diffraction(XRD) and scanning electron microscopy(SEM).The results indicate that:① when the grinding time was 80 min and the specific surface area was 500 m^2/kg,the 28 d activity index of the molybdenum tailings was close to 1.2.The mortar block of 28 d compressive strength is about 52 MPa when cementitious materials is consisting of 40% molybdenum tailings,and the mass ratio of cementitious materials to standard sand is 1:3 with the water-cement ratio of 0.5.② The hydration products of composite cementitious materials are calcium silicate hydrate and ettringite at early stage,which provided the early strength for the mortar block strength.The main products in the later hydration reaction are C-S-H gels,calcium aluminate hydrate and ettringite(AFt),and mortar block strength is provided by the aggregation effect of residual tailings particles and hydration products.