Red mud: Red mud is a waste produced during the process of refining alumina from bauxite.
Bayer process: The Bayer process is a method of extracting alumina from bauxite invented by the Austrian chemist K.J. Bayer from 1889 to 1892. The Bayer process consists of two main processes. The first is the dissolution (i.e. leaching) process of aluminum oxide from bauxite under certain conditions, and then the process of dissolution of aluminum hydroxide from water in supersaturated sodium aluminate solution. These are the two patents proposed by Bayer. The essence of the Bayer process is to extract alumina from bauxite using hydrometallurgy.
Red mud is a waste produced during the process of refining alumina from bauxite. In the Bayer process, after the bauxite is crushed, it is wet-milled together with lime and circulating mother liquor to make qualified slurry. The slurry is pre-desiliconized and then preheated to the dissolution temperature for dissolution. After dissolution, the slurry undergoes auto-evaporation and cooling and then enters the process of dilution and sedimentation and separation of red mud (solid phase residue after dissolution). The secondary steam generated from the evaporation process is used for preheating of the slurry. After sedimentation and separation, the red mud is washed and entered into the red mud yard, and the separated crude liquid (sodium aluminate solution containing solid floating matter, the same below) is sent to the leaf filter.
With the development of the aluminum industry, about 55 million tons of red mud are currently produced in the world every year, and more than 3 million tons of red mud are produced in my country every year. Because a large amount of red mud has not been fully utilized, a large amount of land has been occupied for a long time, causing alkalization of the land and contamination of groundwater, endangering people's health. Scientific and technological workers have made long-term and unremitting efforts to solve this problem and achieved a series of results.
Because the composition and properties of red mud are quite different, the utilization methods of red mud are also different. Abroad, the main method is the Bayer method