(642f) Advances in Technology for Producing Alumina From Complex Resources in China

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The qualified bauxite ore in China to produce Alumina through Bayer process is limited. However, there are considerable complex resources containing significant amount of alumina in China, such as low grade bauxite, fly ash, red mud and nepheline, which can be used to produce alumina through an appropriate process. Compared with low grade bauxite and fly ash, red mud and nepheline, which contain 5-20% of sodium oxide and potassium oxide, could be used to economically extract alumina only through an alkaline sintering or leaching process, because the sodium oxide and the potassium oxide could be leached as valuable hydroxides. However, an acid leaching or sintering process is theoretically suitable to extract alumina from low grade bauxite and fly ash containing tiny sodium or potassium, meanwhile, the purification of the acid leachate is quite important for the development of new acid technology to produce qualified alumina. The improved technologies based on sintering process, alkaline and acid leaching processes to produce alumina from those complex resources in China, and especially, a Low Pressure Hydro-chemical Process (LPHP) leaching technology will be presented.