This article is about bauxite and alumina. Bauxite is the most important aluminium ore. It is formed by the weathering of aluminium-rich silicate rocks in tropical and subtropical climates. Bauxite is a mixture of aluminium hydroxides, oxides of iron and other compounds such as clay minerals and quartz.
In its natural form, bauxite contains aluminium hydroxide, iron oxide and other compounds. When it is processed and smelted, it produces aluminium metal which can then be used in a variety of applications, from aerospace to automobile manufacturing.
Alumina (also known as aluminium oxide) is formed when bauxite is processed. The process requires heat and pure water and when the bauxite is dissolved in it, a calcium aluminate solution is created. This solution is then passed through diaphragm cells that use electrolysis to separate the aluminium oxide.
Alumina has a variety of uses. It is used to make products such as abrasives, ceramics, refractories and chemicals. In addition, alumina is used in the production of aluminium metal, castings and extrusions, and in other products such as catalysts and filters.
Bauxite is mined in many regions of the world. Australia is the world’s leading producer, with over 25% of global production. Other countries with significant bauxite deposits include China, Brazil, India, Guinea and Jamaica.
Bauxite is often processed into alumina in a rotary kiln. This allows for direct exposure to the heat required for aluminium processing. The kiln is usually constructed of steel and lined with refractory bricks to maintain the required temperature and reduce heat losses. During the calcination process, the bauxite mixture is heated to over 800 degrees Celsius, which causes silicon and iron to be removed from the bauxite ore.
In some cases, bauxite is calcined to produce directly reduced alumina. This is a process that involves heating bauxite in the presence of reducing agents, such as carbon or natural gas, to reduce the iron and other impurities present in the bauxite ore. Calcined alumina is primarily used as a feedstock in the production of other aluminium compounds.
Aluminium is essential to the manufacture of a variety of products and to the economy of many countries. It is lightweight, strong, resistant to corrosion and a good conductor of heat and electricity. Bauxite and alumina are essential components in the production of aluminium, and as such, play a significant role in the global economy.
