Abstract Using high aluminum gangue as a raw material, aluminum sulfate 18 hydrate was made by the sulfuric acid leaching method under certain conditions. The product was characterized using X-ray diffraction (XRD) analysis of the phases, x-ray-fluorescence (XRF) analysis of the aluminum and sulfur content and thermogravimetric analysis of the crystallized water [Al2(SO4)3·18H2O]. Change characteristics of the crystal form and morphology during pyrolysis of octadecahydrate aluminum sulfate were studied by thermogravimetric Analysis (TGA), differential scanning calorimetry (DSC), differential thermogravimetry (DTG), XRD and scanning electron microscope (SEM). The theoretical basis for the preparation of metallurgical alumina from octadecahydrate aluminum sulfate was provided. According to the characteristics of the crystal structure change, the pyrolysis process of octadecahydrate aluminum sulfate can be separated into three stages. The first stage (dehydration stage 87–250 °C) had a weight loss rate of 40.5% and a loss of 15 water molecules; the weight loss rate of the second stage (dehydration stage 280–414 °C) was 8.1% with three water molecules lost; the weight loss rate of the third stage (decomposition stage 770–900 °C) was 36.1%, where three SO3 molecules were lost. The pyrolysis products were mainly Al2O3. The activation energies of the three reaction stages were calculated using the Coats-Redfern method as 90.02 kJ/mol, 205.74 kJ/mol and 284.40 kJ/mol, respectively. Graphical Abstract

中文翻译：

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硫酸铝热解过程动力学研究

摘要 以高铝脉石为原料，在一定条件下，采用硫酸浸出法制备18水合硫酸铝。使用相的 X 射线衍射 (XRD) 分析、铝和硫含量的 X 射线荧光 (XRF) 分析以及结晶水 [Al2(SO4)3·18H2O] 的热重分析来表征产物。采用热重分析(TGA)、差示扫描量热法(DSC)、差示热重法(DTG)、XRD和扫描电子显微镜(SEM)研究了十八水硫酸铝热解过程中晶型和形貌的变化特征。为十八水硫酸铝制备冶金氧化铝提供了理论依据。根据晶体结构变化的特点，十八水硫酸铝的热解过程可分为三个阶段。第一阶段（脱水阶段87-250℃）失重率为40.5%，损失15个水分子；第二阶段（脱水阶段280-414℃）失重率为8.1%，损失三个水分子；第三阶段（分解阶段 770-900°C）的失重率为 36.1%，其中三个 SO3 分子丢失。热解产物主要是Al2O3。使用 Coats-Redfern 方法计算出三个反应阶段的活化能分别为 90.02 kJ/mol、205.74 kJ/mol 和 284.40 kJ/mol。图形概要 5%，损失15个水分子；第二阶段（脱水阶段280-414℃）失重率为8.1%，损失三个水分子；第三阶段（分解阶段 770-900°C）的失重率为 36.1%，其中三个 SO3 分子丢失。热解产物主要是Al2O3。使用 Coats-Redfern 方法计算出三个反应阶段的活化能分别为 90.02 kJ/mol、205.74 kJ/mol 和 284.40 kJ/mol。图形概要 5%，损失15个水分子；第二阶段（脱水阶段280-414℃）失重率为8.1%，损失三个水分子；第三阶段（分解阶段 770-900°C）的失重率为 36.1%，其中三个 SO3 分子丢失。热解产物主要是Al2O3。使用 Coats-Redfern 方法计算出三个反应阶段的活化能分别为 90.02 kJ/mol、205.74 kJ/mol 和 284.40 kJ/mol。图形概要 使用 Coats-Redfern 方法计算出三个反应阶段的活化能分别为 90.02 kJ/mol、205.74 kJ/mol 和 284.40 kJ/mol。图形概要 使用 Coats-Redfern 方法计算出三个反应阶段的活化能分别为 90.02 kJ/mol、205.74 kJ/mol 和 284.40 kJ/mol。图形概要