The extraction of aluminium from coal fly ash (CFA) is an important industrial process and has produced commercial interest. However, the leaching kinetics of aluminium has received little attention. This work, therefore, addresses the leaching kinetics of aluminium from fly ash in sulphuric acid. A shrinking core model has been used to investigate aluminium extraction kinetics and its results are presented. The effects of leaching time, solid to liquid ratios and reaction temperature on aluminium extraction rate are studied. The process optimization reveals that the extraction rate can reach up to 68.68% when the fly ash reacts with sulphuric acid at a 1:3 solid to liquid ratios of fly ash / H₂SO₄ (100 g / 300 mL) at 220°C for 4 hour reaction time. The sulphuric acid concentration was maintained constant at 18 M. The leaching rate increases with increasing temperature and solid to liquid ratios. The leaching kinetics indicates that chemical reaction at the surface of the particles is the rate-controlling process during the reaction. The shrinking core model enabled the determination of activation energy of about 60.85 kJ/mol, which is likely to be a consequence of the chemical reaction at the surface of the particles.

中文翻译：

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硫酸从粉煤灰中浸出铝的动力学

从粉煤灰（CFA）中提取铝是重要的工业过程，并产生了商业利益。但是，铝的浸出动力学很少受到关注。因此，这项工作解决了硫酸中粉煤灰中铝的浸出动力学。收缩芯模型已用于研究铝提取动力学，并提出了其结果。研究了浸出时间，固液比和反应温度对铝浸出率的影响。工艺优化表明，当粉煤灰/ H ₂ SO ₄固液比为1：3的粉煤灰与硫酸反应时，萃取率可达到68.68％。（100 g / 300 mL）在220°C下反应4小时。硫酸浓度保持恒定在18M。浸出率随温度和固液比的增加而增加。浸出动力学表明，颗粒表面的化学反应是反应过程中的速率控制过程。收缩核模型能够确定约60.85 kJ / mol的活化能，这很可能是颗粒表面化学反应的结果。