硅石焙烧-酸浸提纯及杂质相结构的演变

Purification of Silica by Roasting-Acid Leaching and Transformation of Metallic Impurity Phases

在硅石提纯过程中,采用XRD和EDS分析硅石中杂质元素赋存特征,采用高温焙烧活化与酸浸复合提纯方法研究了酸浸过程杂质相结构演变及提纯效果.结果表明,硅石中不同类型铝硅酸盐的K,Na,Ca,Al,Si含量不同,主要分为长石类、伊利石和高岭石;酸浸提纯过程中硅石的杂质相不仅会溶解在酸中,且长石类杂质相会演变成伊利石和高岭石.与未预酸浸的硅石提纯相比,预酸浸的硅石经高温焙烧活化提纯后纯度达99.995%,达到高纯石英砂的纯度,杂质Al和K含量分别降低了76.6%和66.5%;在700℃下焙烧,预酸浸硅石的Al和K去除效果最好,去除率分别为85%和41%.

In the purification process of silica, XRD and EDS are applied to analyze the existing characteristics of impurities in silica, and a combined purification method of acid leaching and high-temperature roasting is adopted to study the transformation of impurity phases during acid leaching, and the combined purification effect. The results show that the main phases of aluminosilicate are feldspar, illite and kaolinite based on their different contents of elements such as K, Na, Ca, Al and Si. Not only the impurity phases are dissolved in acids, but also the feldspar impurity phases are changed into illite and kaolinite. The purity of silica after pre-acid leaching and high-temperature activation can reach up to 99.995%, and the contents of Al and K in it with pre-acid leaching are decreased by 76.6% and 66.5%, respectively, compared with its purification without pre-acid leaching. High-temperature roasting at 700℃ can obtain the best effect for removal of Al and K as impurity elements in pre-acid leached silica at the removal rates of 85% and 41%, respectively.