造块焙烧对于酸碱联合法提取粉煤灰中氧化铝工艺的改进

以实现粉煤灰最大利用价值并有效回收氧化铝为出发点,采用造块焙烧引入酸碱联合法的方式来提高粉煤灰的利用率。在造块方式下,最优实验条件得到最高的氧化铝浸出率为84%,通过XRD、SEM等进一步分析了造块方式的优势。该工艺可以实现铝硅分离,硫酸也可以循环使用。动力学研究表明:造块过程粉煤灰颗粒和块样内部毛细通道起到了类似高炉中焦炭的骨架作用,造块处理为反应塑造了介观尺度的多孔结构,在缩小了固液两相之间距离的同时,有效改善了气液两相的传质条件,从而提高氧化铝的浸出率。

IMPROVEMENT OF ALUMINA EXTRACTION FROM FLY ASH BY ACID-ALKALI METHOD WITH LUMP ROASTING

To solve the problem of environmental pollution caused by the extensive accumulation of the fly ash residue, achieve the maximum utilization value from fly ash and alleviate the shortage of bauxite resources in China, the acid-alkali combination method, which was most commonly used for extracting alumina from fly ash, was combined with block roasting to improve the extraction rate from fly ash. The extraction rate of alumina was greatly improved by lump roasting method. Under the optimum condition, the extraction rate of alumina reached 84%. Through XRD, SEM and other mean, the advantages of blockmaking methods were further analyzed. In addition, the process could not only be used to separate aluminium and silicon, but also recycle sulfuric acid. Kinetic studies showed that the internal capillary channels of fly ash particles and the lumps played a skeleton role similar to that of coke in blast furnaces. Block making treatment created a mesoscopic porous structure for reaction, which not only reduced the distance between solid and liquid phases, but also effectively improved the mass transfer condition of gas and liquid phases, thus enhancing the extraction of aluminium.