The Bauxite Mineral Processing Flow

As the main raw material for producing metallic aluminum, bauxite is widely used in many fields such as aerospace, construction, and transportation. The bauxite mined from nature needs to go through a complex mineral processing flow to extract high-quality alumina, laying the foundation for subsequent aluminum smelting.

The first step in bauxite mineral processing is crushing and grinding. The bauxite ore just mined is large in size and high in hardness. It is gradually crushed into smaller ore blocks by equipment such as jaw crushers and cone crushers. Subsequently, with the help of grinding equipment like ball mills, the ore blocks are further ground into slurry, fully dissociating the useful minerals in the bauxite from the gangue minerals, creating conditions for subsequent separation.

The slurry after crushing and grinding enters the pre-selection stage. Pre-selection usually involves washing and screening to remove the soil and impurities on the surface of the ore and sieve out materials with inappropriate particle sizes. During the washing process, the clay and other impurities attached to the surface of the ore are separated by the scouring of water flow and mechanical stirring, improving the purity of the ore and reducing the load of subsequent processing.

After pre-selection, an appropriate mineral processing process needs to be selected according to the type and quality of bauxite. For gibbsite-type bauxite, the Bayer process is often used. In this method, the ground bauxite is first mixed with sodium hydroxide solution, and a dissolution reaction is carried out under high temperature and high pressure conditions, causing alumina to react with sodium hydroxide to form sodium aluminate solution, while impurities such as iron oxide and silica form insoluble substances. Through sedimentation and filtration, the clear liquid containing alumina and red mud are separated. The clear liquid is then cooled, seeded, and other operations are carried out to decompose the sodium aluminate solution and precipitate aluminum hydroxide. Finally, high-purity alumina is obtained through calcination.

For diaspore-type bauxite, due to the difficulty of dissolving alumina, in addition to the enhanced Bayer process, flotation is often combined for treatment. During flotation, specific collectors and regulators are added to change the surface properties of the minerals, making the alumina minerals adhere to the bubbles and separate from the gangue minerals, improving the recovery rate and grade of alumina.

After a series of separation processes, the obtained aluminum hydroxide product needs to enter the calcination stage. In a high-temperature calcining furnace, the aluminum hydroxide undergoes a dehydration decomposition reaction and is converted into activated alumina. The activated alumina can be further processed into alumina products with different crystal forms and uses to meet the needs of different industrial fields.

From bauxite to alumina, every process in the mineral processing flow is closely linked, and every operation step embodies the power of science and technology, ensuring the efficient utilization of bauxite resources and continuously supplying important raw materials for modern industrial development.