石棉尾矿盐浸渣制备超细白炭黑的工艺条件研究

Preparation and Influencing Factor Research of Ultrafine Silica Powder Prepared from Salt Leaching Residue of Asbestos Tailings

以石棉尾矿盐浸渣为原料,通过碱浸制成偏硅酸钠溶液。向反应容器底液中同时注入偏硅酸钠和硫酸溶液,控制底液pH值稳定在7.5左右沉淀超细白炭黑。考查了超细白炭黑制备过程中偏硅酸钠浓度、反应温度、表面活性剂和电解质用量以及干燥方式对白炭黑样品性能的影响;采用扫描电子显微镜、X射线衍射仪、红外光谱仪及激光粒度分析仪等对所制备白炭黑样品的形貌、物相和粒径等进行了表征。结果表明,偏硅酸钠浓度和温度对白炭黑的生成率有较大影响,醇洗能够有效控制和减少白炭黑样品的团聚现象,在最佳实验条件下制得的白炭黑样品化学结构为无定形水合二氧化硅,比表面积(BET)为102.43m2/g,白炭黑生成率达75%以上。

Ultrafine silica powder was prepared via simultaneous injection of sodium metasilicate and sulfuric acid solution into a reaction vessel under constant pH value of 7.5. The sodium metasilieate was prepared from salt leaching residue of asbestos railings via alkaline leaching. Influencing factors of properties for ultrafine silica powder, including the concentration of sodium metasilicate, temperature, amount of surfactant and electrolyte and drying methods were investigated. The morphology, structure and particle size of the silica samples were characterized by scanning electron microscopy, X-ray diffraction, infrared spectrometer and laser particle size analyzer. The results indicates that the yield of silica is greatly influenced by the concentration of sodium metasilicate and temperature, the aggregation phenomena of the silica can be controlled by washing the precipitum with ethanol. The chemical structm-e of the silica is amorphous hydrated silicon oxide, the specific surface area is 102.43 m2/g and the yield of the silica is above 75% at the optimum experimental conditions.