硫酸钠激发尾矿充填材料的性能与微观结构

以铅锌尾矿、硅酸盐水泥、矿粉为原材料,硫酸钠为碱性激发剂,设计制备了高流动性早强尾矿充填材料(以下简称充填材料),研究分析了硫酸钠掺量、矿粉含量对充填材料流动度、凝结时间、力学性能、反应产物物相组成和微观结构的影响.结果表明:随着矿粉含量的增加,充填材料的凝结时间延长,流动性增加,早期强度降低;硫酸钠可以缩短充填材料的凝结时间,并提高充填材料的早期强度;硫酸钠提供的硫酸根离子促进早期钙矾石(AFt)的形成,减少了自由水数量,增加了颗粒间的胶结程度;硫酸钠可显著提高充填材料孔溶液pH值,加速矿粉的早期水化.

Properties and Microstructure of Cemented Paste Tailings Activated by Sodium Sulfate

Cemented paste tailings(CPT) with high flowability and early strength was prepared with lead zinc tailings, Portland cement, and slag, using sodium sulfate as an alkali activator. Effects of sodium sulfate use level and slag to cement ratio on workability, compressive strength, setting time, phase composition, and microstructure of CPT were evaluated. The result shows that increasing the slag content in the mixtures leads to an increase in flowability, whereas the setting time is prolonged, and the early age strength is decreased. The use of sodium sulfate as an alkali activator shortens the setting time of CPT and promotes strength development, especially at the early age. Incorporating sodium sulfate provides SO2-4 that promotes the formation of ettringite, reduces the free water in the pore solution and leads to a densified structure. The use of sodium sulfate as an alkali activator raises the pH of the pore solution and accelerates the early age hydration of slag.