Dry beneficiation of bauxite minerals for greater yields

The primary starting material for aluminum refining is bauxite. Since aluminum is a reactive element and does not occur naturally, aluminum-rich ore needs to be refined to produce alumina and aluminum, resulting in a significant generation of by-product residue.

The biggest downfall in the bauxite refining process, the Bayer process, is the creation of alumina refinery residues (ARR)—also known as “red mud”—a toxic sludge that needs to be contained in holding ponds and monitored for long periods of time, at high cost. This sets the stage for potentially devastating environmental and human health disasters if the holding ponds fail for any reason and the red mud gets into local water sources or populated areas. Despite much ongoing research, there is no commercially significant level of red mud beneficial reuse.

ST Equipment & Technology LLC (STET) has developed a tribo-electrostatic belt separator that is ideally suited for the beneficiation of very fine (less than one micron) to moderately coarse (500 microns) mineral particles. The high throughput rate process is energy efficient and capable of increasing available alumina in bauxite while reducing reactive and total silica.

The STET process is entirely water and chemical free, resulting in a dry bauxite co-product that can be beneficially reused in cement manufacture, unlike red mud. The STET process removes some of the contaminants that would otherwise be rejected by the Bayer process as red mud. However, the STET process operates at a fraction of the cost of the Bayer process. In addition, the upgraded bauxite results in savings in the Bayer process, including lower consumption of caustic soda, reduced need for fresh water source, savings in energy due to a lower volume of inert oxides, and a reduction of red mud by-products. In some situations, the tailings for the STET separator; a water-free and chemical-free, low grade bauxite, could even be sold to cement producers to offset processing costs.

In addition, STET technology may offer bauxite producers and alumina refiners other added benefits including reduced bauxite logistics costs, extension of red mud disposal site life, and extended operating life of existing bauxite mines by improving quarry utilization and maximizing recovery. The water- and chemical-free by-products produced by the STET process are also usable for the manufacture of cement in high volumes without pre-treatment.

If you add it all up, that’s a lot of “wins” you can put to work for your alumina operations. Contact ST Equipment & Technology and let us help you gain more from your current operations while lowering your operating costs and increasing your environmental friendliness.