提纯石棉尾矿酸浸渣制备无定型二氧化硅粉体

Preparation of amorphous silica powder by purification of acid leaching residue of asbestos tailing

对提纯石棉尾矿酸浸渣制备无定型二氧化硅的最优工艺条件进行研究。采用对石棉尾矿酸浸渣的超细粉碎、酸浸和煅烧等方法进行提纯实验，并通过扫描电子显微镜、X射线衍射等手段对样品进行表征。结果表明，最佳提纯工艺条件为：将酸浸渣超细粉碎至d50=2．50μm，d97=11．35μm，用10％盐酸酸浸1h，最后在70000下煅烧0．5h。得到的二氧化硅比表面积为247m^2／g，SiO2〉90％，符合GB10507-89中A类标准要求。石棉尾矿酸浸渣的颗粒形状与石棉尾矿的颗粒形状基本一致，包含块状、针状等颗粒，而经过提纯处理后的酸浸渣则为块状超细颗粒。提纯前酸浸渣的矿物组成为蛇纹石20％，石英8％，滑石6％，非晶质SiO266％；提纯后矿物组成为石英6％，非晶质SiO2 90％，滑石4％。

The optimal technical condition of the preparation of amorphous silica by purifying acid leaching residues of asbestos tailings was raported. Purification experiment was accomplished by the methods such as superfine grinding, acid leaching, and calcination. The characterization of the samples was completed via Scanning Electron Microscopy and X-ray diffractometry. The research result indicates that the optimal purification conditions are as follows： super-fine grinding the acid leaching residues to d50=2.50 μm, d97=11.35 μm, followed by hydrochloric （the mass concentration is 10%） acid leaching for 1 h, then calcining for 0.5 h at 700 ℃. The specific surface area of the amorphous silica is 247 m^2/g, and the total content is above 90%, which can meet the quality index of criterion A in GB10507-89. The grain shape of acid leaching residues of asbestos tailings is basically identical with those of asbestos tailings, including massive needle-shape particles, while the purified acid leaching residues are superfine ones. The unpurified mineral composition is serpentine 20%, quartz 8 %, talc 6 %, and amorphous silica 66%（mass fraction）; however, that of the purified sample is quartz 6%, amorphous silica 90 %, and talc 4 %.