氧化铝对煤矸石提铝废渣制备水玻璃的影响

Effect of alumina content on preparation of water glass using slag from acid leaching of coal-waste

以纯石英砂或煤矸石酸浸提铝废渣为原料,采用低温(850℃)纯碱烧结法制备水玻璃,考察了杂质Al2O3含量对原料中Si O2溶出率以及产品水玻璃模数的影响,通过电感耦合等离子发射光谱(ICP)、傅里叶红外光谱仪(FTIR)、X射线衍射仪(XRD)和热重分析(TGA)手段对原料和产物进行了分析和表征。结果表明,与纯石英砂为原料制备水玻璃相比,杂质Al2O3的存在降低了Si O2-Na2O体系的反应温度,但由于Al2O3会与反应体系中的Si O2和Na2O反应生成水不溶性的铝硅酸钠盐,导致实际可溶性Si O2的含量减少,降低了Si O2的溶出率和硅酸钠的模数。通过添加石英砂可控制提铝废渣中的A12O3含量低于5%,使提铝废渣中Si O2的溶出率达到90%以上,制得水玻璃模数达2.15。

Water glass was prepared by a low temperature soda-sintering technique(850℃) using slag from acid leaching of coal-waste or quartz sand as the feedstock. The effect of the content of impurity Al2O3 in the feedstock on the solubility of Si O2 and the modulus of the prepared sodium silicate were investigated systematically. The feedstock and the products were characterized by inductively coupled plasma( ICP),Fourier transform infrared spectroscopy( FTIR),X-ray diffraction( XRD) and thermogravimetric analysis( TGA). In comparison to the high water-solubility of the prepared water glass with pure quartz sand and sodium carbonate,the solubility of the product obtained with slag from acid leaching of coal-waste decreased remarkably due to the formation of insoluble sodium hydroaluminosilicates between impurity Al2O3 and Si O2 during the low temperature sintering process although the existence of Al2O3 lowered the melting temperature of Si O2-Na2 O system. Consequently,the modulus of the obtained sodium silicate reduced as well. The content of Al2O3 in the feedstock could be controlled to 5% or lower by adding a certain amount of quartz sand,and thus the dissolution rate of silica in slag reached up to 90% and the modulus of water glass was 2. 15.