Abstract: This paper studied on aluminum leaching from coal ash in fluidized bed boiler(CFB) produced from northeast China. The coal ash was leached by sulfuric acid under various conditions to get suitable aluminum dissolution with less energy and acid cost. The products were acid solutions with rich aluminum sulfate and residue high in silicon. The results of acid leaching experiments showed that the aluminum dissolution was 91.5%, and the content of SiO₂ in high silicon residue reached 87.6% under the suitable leaching conditions of sulfuric acid 5 mol/L, reaction temperature 105—110℃、reaction time 2h and ratio of solid to liquid 1:3. X-ray diffraction(XRD)and scanning electron microscopy(SEM)analysis showed that the aluminum element in the raw coal ash mainly occurred in amorphous phase. The high chemical reactivity of the amorphous material contributed to the high aluminum leaching rate. Thus, coal ash from kind of circulating fluidized bed boiler is suitable for aluminum leaching and silicon extracting.

Key words: coal ash, amorphous, acid leaching, aluminum oxide

摘要： 为实现煤炭资源化分级利用,对东北某热电厂循环流化床锅炉灰渣进行提铝研究。用硫酸在不同的反应条件下酸浸,以获得较高的铝浸出率和合适的酸浸条件,产品为富含硫酸铝的酸浸液和高硅提铝残渣。酸浸实验结果表明,较为合适的酸浸条件为:5mol/L的硫酸、105～110℃的酸浸温度、2h的反应时间和1:3的固液比,此时铝浸出率为91.5%,提铝残渣中SiO₂含量高达87.6%。X射线衍射分析(XRD)和扫描电镜(SEM)分析表明,原始煤灰渣中的铝元素主要以非晶态的化合物形式存在,而非晶态物质具有较高的化学反应活性,促成了较高的铝浸出率。因此,这种循环流化床锅炉的灰渣酸浸提铝提硅较为合适。

关键词: 灰渣, 非晶态, 酸浸, 氧化铝