The production of aluminum ingots is composed of bauxite mining, alumina production, and aluminum electrolysis.
The bauxite ore is first mined, and aluminum ore powder is produced through water washing and grinding processes, and then alumina is obtained through four complex processes such as roasting. There are three main types of bauxite for the production of alumina: gibbsite and monohydrate. Water diaspore, boehmite.
Of the proven global reserves of bauxite, 92% are weathered laterite-type bauxite, which belongs to the gibbsite type. These bauxites are characterized by low silicon, high iron, and high aluminum-silicon ratio, and are concentrated in Africa West, Oceania and Central and South America. The remaining 8% is sedimentary bauxite, belonging to boehmite and diaspore type, with medium and low grades, mainly distributed in Greece, the former Yugoslavia and Hungary.
Due to the different characteristics of the three types of bauxite, each alumina production enterprise adopts different production processes in production, mainly including Bayer method, soda lime sintering method and Bayer-sintering combined method. Generally, high-grade bauxite is produced by the Bayer method, and medium and low-grade bauxite is produced by the combined method or the sintering method. Due to its simple process and low energy consumption, the Bayer process has become the main method used in the current alumina production, and its output accounts for about 95% of the global alumina production.
Alumina is electrolyzed to produce aluminum metal under the action of a strong current. This process is called electrolytic aluminum;