[Chinese aluminum industry network] method has the alkali method, the acid method and the electrothermal method three kinds. Acid and electrothermal methods are still used in industrial applications, while the alkali process is the main method for producing alumina. Alkali method can be divided into Bayer method, sintering method and joint method. Xi'an Jmlai Bio-Tech Co., Ltd. , https://www.jmlaisarms.com
The Bayer process alumina production process consists of raw slurry preparation, high pressure leaching, pressure boiler digestion and red mud separation and washing, species decomposition, alumina grading and washing, aluminum hydroxide roasting, mother liquor evaporation and soda ashing. . The Bayer process is only suitable for the treatment of low-silicon high-quality bauxite, and it is uneconomical to treat the high-silica bauxite because the SiO2 in the ore is converted into aqueous aluminosilicate when it is dissolved and thus it needs to consume a large amount of NaOH. The effective method for treating high silica bauxite is alkali-lime sintering.
Alkaline-lime sintering process for producing alumina includes raw slurry preparation, clinker sintering, clinker leaching, red mud separation and washing, crude liquid desiliconization, selenium carbonate decomposition, aluminum hydroxide separation and washing, aluminum profiles Aluminum hydroxide roasting and mother liquor evaporation and other processes.
Alkali-lime sintering method is suitable for the treatment of high-silica bauxite, especially the type of ore-aluminous type in China, and the ore-silicon ratio is less than 4 ore. Sintering is more advantageous. Compared with some Bayer plants that do not have high-grade bauxite, the sintering method has low alkali consumption and high total alumina recovery. The disadvantages are complex production processes, high equipment investment, high consumption, and high product quality. difference.
The joint method is a method developed based on the advantages and disadvantages of the Bayer process and the sintering process. Joint methods are parallel, series and mixed three.
When the treated bauxite is a medium grade, the ore is first leached by the Bayer process. After the leached red mud, the alumina and sodium oxide are further extracted by the sintering method. The economic effect. It is possible to greatly reduce the scale of the equipment for the sintering, leaching and desilication processes that require large investment in the sintering process. Alkali and alumina in Bayer's red mud can be fully recovered. If a part of low-grade bauxite is added to the raw material prepared from Bayer's red mud, raising the slag aluminum silicon to facilitate the operation of the sintering kiln will not only improve the technical operation of the large kiln, but also provide a part of the sintering process. Alkali and aluminum profiles that are needed in the Alpha part can also achieve good economic results. This is a joint method that combines the characteristics of series and parallel, which is called hybrid joint method.