Aluminum is the most common metal element found on Earth. However, the aluminum we use today comes in the form of aluminum metal and alumina, also known as aluminum oxide, which is produced from bauxite. In order to release the raw alumina, bauxite must go through what is known as the Bayer process, where the bauxite is crushed, then heated in a pressurized vessel and dissolved with sodium hydroxide (caustic soda). The alumina is then separated from the other components and impurities contained in the bauxite so that it can eventually be refined into aluminum.
Unfortunately, the waste left behind—called red mud—is toxic and must sit in holding pools until it can stabilize. These impoundments are often reinforced with clay or synthetic liners that keep the caustic materials from seeping into the surrounding soil or ground water. However, there have been a number of instances when reservoirs of red mud have breached their confinements and caused catastrophic environmental issues.
ST Equipment & Technology has a better way to produce alumina. The STET process removes the reactive silicates and inert oxides (Fe, Ti) from bauxite without the use of caustic materials or wet separation processes. Through our unique triboelectrostatic dry separation process, a greater degree of alumina can be extracted from the bauxite with before going through the Bayer Process. The remaining elements from the process can be used in ceramic production, as well as Portland cement manufacturing. The fine powder created by the process can be managed with water to prevent it from creating dust clouds, but the resulting “mud” does not contain caustic materials and is perfectly safe for the environment.
So, if you add up all the benefits, ST Equipment & Technology’s method is a much better alternative. It saves on operating costs by lowering the use of caustic soda, which is both a cost benefit as well as an environmental blessing. It also saves money by performing pre-Bayer processing of the bauxite, resulting in less energy needed to heat and pressurize the post-separated materials. And, the ST Equipment & Technology process is energy efficient, so it can rapidly process a high volume of materials to keep mining operations moving forward.