We describe a process of chlorination of fly ash with either chlorine gas or calcium chloride, which successfully decomposes mullite and permits the extraction of a number of industrially useful, acid-soluble compounds. As a guide for determining optimal input molar ratios and temperatures, the Gibbs energies for three groups of reactions of major fly ash components between 973 K and 1473 K were calculated: (1) chlorination with chlorine gas; (2) chlorination with chlorine gas in the presence of coal; (3) chlorination with calcium chloride. Laboratory-scale measurements with fly ash from six coal combustion power plants in Kazakhstan show that chlorination with either calcium chloride or chlorine gas allows efficient extraction of alumina (α-Al2O3) and silica with both high yield and purity.

中文翻译：

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电厂粉煤灰处理氯化产生的氧化铝和二氧化硅

我们描述了用氯气或氯化钙对飞灰进行氯化的过程，该过程成功地分解了莫来石并允许提取许多工业上有用的酸溶性化合物。作为确定最佳输入摩尔比和温度的指南，计算了主要飞灰组分在 973 K 和 1473 K 之间的三组反应的吉布斯能：(1) 用氯气氯化；(2)在煤的存在下用氯气氯化；(3)用氯化钙氯化。对哈萨克斯坦六家燃煤电厂的飞灰进行的实验室规模测量表明，用氯化钙或氯气氯化可以高效提取氧化铝 (α-Al2O3) 和二氧化硅，并具有高产量和纯度。