Sodium Aluminate Production Method
May 02, 2023
1. Bayer method
The bauxite is crushed and finely ground, then mixed with caustic soda solution, sent to an autoclave and boiled at high temperature, so that the alumina in the bauxite is turned into sodium aluminate and transferred into the solution, and separated to obtain Sodium aluminate solution, the product is obtained after evaporation. In recent years, the high-pressure dissolution process of lye has developed from discontinuous to continuous, and pipeline dissolution has begun to be used in Bayer process production.
2. Sintering method
Grind and mix bauxite, soda ash, and limestone, sinter at a high temperature above 1200C, leach the clinker with water, and remove silicon from the leached sodium aluminate solution to obtain a refined sodium aluminate solution, which is evaporated to dryness. To obtain products, the sintering method is divided into dry material sintering method and wet material sintering method. At present, the wet material sintering method has basically replaced the dry material sintering method.
3. Joint law
The so-called combined method refers to a production method in which the Bayer method and the sintering method are used simultaneously. In the production, if the Bayer method is the main method and the sintering method is supplemented, the high-silicon bauxite is treated by the Bayer method, and then the red mud obtained is treated by the sintering method, which is called the series combination method. If the low-silicon bauxite is treated by the Bayer method, and the high-silicon bauxite is treated by the sintering method, the two methods are carried out at the same time in the production process, and then the crude liquid obtained by the two methods is combined, which is called the parallel combination method, and the obtained The sodium aluminate solution is evaporated to obtain the product.
4. Alkaline hydrolysis of aluminum hydroxide
Add crude aluminum hydroxide to sodium hydroxide solution at a temperature of 50-80°C and raise the temperature to 110°C, keep warm for 3 hours to obtain sodium aluminate solution, and evaporate to dryness to obtain the product.
The Bayer method is suitable for bauxite with low silicon content. The process is simpler than the sintering method, with less investment, lower cost and high product quality. lowered. The fluke knot method is suitable for using high-silicon-lead bauxite as raw material. Compared with the Bayer method, the process is more complicated, the investment is larger, the cost is high, and the product quality is also poor, but the total recovery rate of alumina is higher. The combined method has the characteristics of the above two methods, both high-silicon bauxite and low-silicon bauxite can be used.
