四川某尾砂充填材料物理性能及其重金属稳定性研究

为查清四川某尾砂充填材料理化特性和重金属毒性,以尾矿和普通水泥为原料制备井下充填材料,采用全因子试验探究尾砂粒径及灰砂比对试样物理性能及重金属稳定性的影响,SPSS 软件进行回归分析充填材料流动度和抗压强度,运用 XRD、FTIR 和 SEM 等分析方法,揭示充填材料水化反应过程及其重金属固化机理。 试验结果表明:尾砂粒度越粗,灰砂比越大,尾矿充填料的抗压强越大,易满足井下充填材料的强度要求,但尾砂粒度过大时,片状或棱型等不规则形状颗粒导致充填料流动性能降低;粗粒级尾砂充填料水化反应充分,水化产物与重金属离子相互作用,通过沉淀、静电吸附、离子置换作用等,将重金属滞固在充填材料中,重金属浸出毒性至少满足地下水Ⅲ 类水质要求。 因此采用水泥为胶凝材料,制备尾砂井下充填材料的理化特性和重金属稳定性均满足要求。

Study on Physical Properties and Heavy Metal Stability of a Tailings Filling Material from Sichuan

In order to reveal the physicochemical properties and heavy metal toxicity of a tailings filling material in Sichuan,tailings and common cement were used as raw materials to prepare the underground filling materials. Full-factor test was used to explore the influence of tailing particle size and cement-sand ratio on the physicochemical properties and heavy metal stability of samples. Regression approach with SPSS software was conducted to study the fluidity and compressive strength of filling materials. XRD,FTIR and SEM were carried out to reveal the hydration reaction process and the stabilization mechanism of heavy metal in filling materials. The test results showed that the compressive strength of the tailings filling material increased with increasement of the tailings particle size and the cement-sand ratio. The filling material with the coarse tailings met easily the strength requirements. However,the large flake and angular particles led to the decreasement of the flow performance of the filling material. The heavy metal was immobilized in the coarse tailings filling materials through precipitation,electrostatic adsorption and ion replacement during the hydration reaction process of cement. The leaching toxicity analysis showed that heavy metals concetration met the Ⅲ groundwater water quality standard. The tailings underground filling material consisted of the tailings and the cement was reliable and safe,which meet the requirement of physicochemical properties and heavy metal stability.