China's alumina production process

China's aluminum oxide plant Hu 6: 2003 alumina production in Shanxi Aluminum Plant 1.41 million t; Henan Aluminum Company of 1.37 million t; Zhongzhou Aluminum 850 000 t; Shandong Aluminum 930 000 t; Pingguo Aluminum Company 69 Wan t; Guizhou Aluminum Factory 750,000t. We have been producing metallurgical grade alumina. Pingguo Aluminum Company adopts the pure Bayer method, and other factories use the hybrid method. The Bayer method and the sintering method in the hybrid method are basically equal, and the process flow is shown in Figure 1.

Figure 1 Basic process flow chart of alumina production in China

China's bauxite is a diaspore type, requiring a dissolution temperature higher than 240 ° C, which is a relatively difficult to dissolve ore. China's bauxite has relatively low aluminum and silicon (6-9). The raw materials determine that China's alumina production consumes more energy than foreign countries and costs more. China's alumina industry started from the sintering method. Due to the adoption of a series of technologies such as unsaturated formulation, low caustic ratio dissolution, raw slurry addition coal desulfurization and deep desiliconization, the sintering method has achieved new development and achieved remarkable results. However, the sintering method has a large amount of materials and a complicated process, especially in the main process of high temperature burning, and the energy consumption is particularly high, the energy consumption per ton of alumina reaches 40 GJ, and the energy cost accounts for 53% of the production cost. It is obvious that the soda lime sintering method lacks competitiveness in the international market. To this end, China's Great Wall Aluminum Corporation alumina plant in the world first adopted the "Bayer-sinter" hybrid joint production of alumina. After more than 30 years of hard work, this method has been improved day by day. The total recovery rate of alumina is 92.2%, and the alkali consumption (calculated as Na ₂ CO ₃ ) is 69kg/t. Compared with the sintering method of Shanxi Aluminum Plant, the production cost is lower than 15%. As a result, the Guizhou Aluminum Plant changed from 1989 to a mixed-process method to produce alumina. In 1992, Shanxi Aluminum Plant changed to alumina production by mixing method. Shandong Aluminum Plant and Zhongzhou Aluminum Plant were also changed to the hybrid method.