关键词: 灰渣, 非晶态, 酸浸, 氧化铝

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