- 21 November 2024
Despite the fact that aluminum is the most common metal on the planet, it cannot be found in pure form on Earth. Due to its high chemical activity, aluminum atoms easily combine with other substances. However, this metal cannot be obtained by smelting ore in a furnace, as is the case with iron, for example. The process of producing aluminum is much more complicated.
The production of aluminum is divided into three main stages: the mining of bauxite - an ore containing aluminum, its processing into aluminum oxide and, finally, the production of pure metal by electrolysis - the decomposition of aluminum oxide into its constituent parts under the action of an electric current. From 4-5 tons of bauxite, 2 tons of aluminum oxide are obtained, from which 1 ton of aluminum is produced. As for what aluminum is, there are several types of aluminum ores in the world. It is also important to know what aluminum is made of. The main raw material for the production of this metal is bauxite. It is a rock consisting mainly of aluminum oxide mixed with other minerals. Bauxite is considered to be of high quality if it contains more than 50% aluminum oxide.
The world's bauxite reserves are estimated at 18.6 billion tons. At current production levels, this provides aluminum demand for more than a century. About 90% of the world's bauxite resources are concentrated in tropical and subtropical countries - 73% of which are in five countries: Guinea, Brazil, Jamaica, Australia and India.
Most often, bauxite is mined by open-pit methods - using special equipment, the ore is "cut" layer by layer from the surface of the earth and transported for further processing. However, there are places in the world where aluminum ore lies very deep and mines have to be built to extract it.
The next step in the production chain, is the processing of bauxite into aluminum oxide - this is Al 2 O 3 aluminum oxide, which is a white, brittle powder. The main method of producing alumina in the world is the Bayer method, which was discovered more than a century ago, but is still valid - about 90% of the world's alumina is produced this way. This method is very economical, but it can only be used when processing high-quality bauxite with a relatively low content of impurities - primarily silica. According to the Bayer method, crystalline aluminum hydroxide, which is part of bauxite - dissolves well at high temperatures in a solution of caustic soda (caustic base, NaOH) at high concentration, and when the temperature and concentration of the solution decreases, it crystallizes again. Foreign substances contained in the composition of bauxite (the so-called ballast) do not transform into a soluble form, nor do they recrystallize and precipitate before the crystallization of aluminum hydroxide occurs. So we already know what aluminum is and what aluminum is made of. It is now worth learning about its uses.
In a foundry, aluminum is shaped not only into various shapes, but also into alloys. These are formed by introducing various metals (so-called alloying additives) into aluminum - some increase its hardness, others increase its density, others lead to changes in its thermal conductivity, etc. Boron, iron, silicon, magnesium, manganese, copper, nickel, lead, titanium, chromium, zinc, zirconium, lithium, scandium, silver, etc. are used as additives. Currently, more than 100 grades of aluminum alloys are used in industry.
The use of aluminum is mainly in construction, production of electrical equipment and in transportation. Items made of aluminum can also be found in everyday life. These include pots, cutlery, but also windows and doors. Less well-known aluminum items are power cables, structural connectors.
The largest use of aluminum is in construction, but it is also growing in the aerospace industry. Aluminum is extremely popular for aircraft construction because it is lightweight, strong, corrosion-resistant, durable and ductile. Weight reduction alone is crucial for aircraft and spacecraft. For the same reason, aluminum is widely used in car manufacturing. It has helped reduce the weight of cars and trucks.
