The extraction of alumina from coal fly ash is one of the most important value-added utilization ways.The fly ash has been activated through adding additive sodium carbonate because the stability of mullite structure in fly ash leads to leaching alu-mina difficultly.Mullite structure in fly ash can transform into nepheline which tends to dissolve in acid if the fly ash and sodium carbonate react at high temperature in muffle furnace.Then,the resulting active mixture extracted by sulfuric acid,the Al2 O3 was transferred to solution,realizing the separation of alumina and silicon.The effects of coal fly ash and sodium carbonate mass ratio,sulfuric acid concentration,acid leaching time,liquid-solid ratio and acid leaching temperature on the leaching of alumina were investigated.The results show that the alumina extraction yield can reach 94% under the condition of the mass ratio of the coal fly ash and sodium carbonate mass ratio as 1:0.8,sulfuric acid concentration as 25%,acid leaching time as 2 h,the liquid-solid ratio as 5 mL/g,acid leaching temperature as 98 ℃.%针对粉煤灰中莫来石结构稳定导致氧化铝难浸出的问题，提出用碳酸钠作为助熔剂对粉煤灰进行活化的方法。将粉煤灰与碳酸钠放入马弗炉中进行高温反应，使莫来石转变为易溶于酸的霞石；然后使用硫酸进行酸浸，将活化样品中的氧化铝转移到溶液中，实现铝、硅分离。对粉煤灰与碳酸钠质量比、硫酸质量分数、酸浸时间、酸浸温度等因素对氧化铝浸出率的影响进行考察。结果发现：当粉煤灰与碳酸钠的质量比为1：0．8，硫酸质量分数为25％，液、固比为5 mL／g，酸浸温度为98℃，酸浸时间为2 h 时，粉煤灰中氧化铝的浸出率最高，可达94％。
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