Bauxite refineries produce alumina (Al₂O₃) which is used primarily as a feedstock for the aluminum reduction industry. Waste muds created by the extraction of alumina from its ore, bauxite, may contain low levels of Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM), usually:

• Uranium.
• Thorium.
• Radium.
• Their decay productsdecay productsThe atoms formed and the energy and particles emitted as radioactive material decays to reach a stable form..

Learn more about TENORM-producing industries and sources in the United States.

Waste Generation

Most bauxite is imported from countries in Africa and South America and from Jamaica. Only a few surface mines in Arkansas have been responsible for all recent bauxite mining in the United States.

The refinery processes generate about one ton of solid waste during the production of a ton of aluminum. This includes a small amount of waste rock, waste "muds" and a small amount of other scrap and solid wastes coming from the smelter.

Wastewater from Mining

The only ore beneficiation operations performed at bauxite mines are crushing and grinding. Water used for dust suppression, water drained from the mine, and surface runoff generate a small volume of wastewater. This water is neutralized by lime and then discharged into nearby streams.

Refinery "Muds" from Processing

Dried bauxite is mixed with hot caustic solutions to dissolve alumina. The bauxite residue, called "red mud," is removed in settling tanks and placed in a tailings impoundment near the plant. In some plants, red mud is further processed to produce aluminum oxides. The waste product from this process is called "brown mud." 

The refinery muds (both red and brown mud) dry to a solid with very fine particle size (about 1 μm) and contain significant amounts of iron, aluminum, calcium, and sodium. They may also contain trace amounts of TENORM and other various elements. The types and concentrations of minerals present in the muds depend on the composition of the ore and processing conditions.

Disposal and Reuse

Red and brown muds are caustic and no secondary use has been made of the waste. However, muds might be used for land reclamation, for the construction of site dams or embankments, or as a feed material for other extraction processes because of the high iron content (20 to 50 percent). The EPA has identified elevated arsenic (16 micrograms per gram (μg/g)) and chromium (374 μg/g) concentrations in some mud samples.