Aluminum is one of the most well-known materials existing on the planet. However, pure aluminum does not occur naturally, and a chain of processes is required to develop the usable material for different purposes. Many compounds are quickly produced due to the easy atom binding in this metal. Simultaneously, it is impossible to isolate the metal by simply melting the compounds in a forge, as in metals such as iron. The pure aluminum production process is very complex and requires special machines and vast amounts of electricity. Thus, smelters for this metal are always built in the vicinity of power energy sources, including hydroelectric power plants that do not contaminate the environment. Now let’s get to know the best practice methods and steps for producing pure aluminum material.
Bauxite Mining for Creating Pure Aluminum
Pure aluminum production is essentially broken down into three main stages. The first step is extracting the bauxite, which contains aluminum from the ground. The second step is processing the bauxite into alumina or aluminum oxide. Finally, the third stage produces pure aluminum by using an electrolytic reduction in which the aluminum oxide should be broken down into its components by utilizing electric current. About 1 tone of pure metal is made from 4-5 tons of bauxite, producing 2 tons of alumina.
There are many different minerals available from which pure aluminum can be produced for other industrial materials, such as Aluminum composite panels. Bauxite is a raw material that is commonly used for this purpose. Bauxite generally contains 50% aluminum oxide mixed with some other substances.
Bauxite is available in different variations. It can structurally be dense, solid or crumbly. Usually, it has brick re, flaming red or brown color due to the existence of iron oxide. The bauxite can be grey or white in case of lower iron content. However, dark green, yellow, and even multi-colored bauxites with purple, bluish, black and red strains are available too.
The most practical way to mine minerals is by utilizing open-pit mines. Special equipment is used to cut one layer after another off the surface, including rocks, and then transported to factories for further processing. However, there are other areas where aluminum ore needs to be mined from deep underground layers, which require underground mines.
Alumina Production for Pure Aluminum
The next step in the pure aluminum production chain is obtaining aluminum oxide from bauxite, also known as a white powder. Bayer process is one the most common methods of producing alumina from the mineral. This method is discovered over a hundred years ago and is still a very a suitable system.
About 90% of alumina producers utilize the Bayer method. This system’s only issue is that the Bayer process is efficient on high-quality bauxite with low admixtures, such as silicon. This method’s instruction is as follows: Dissolving the crystallized aluminum hydrate in concentrated caustic soda at high temperature. After the temperature is lowered and the solution’s concentration increases again, the material reduces but the other elements existing in the bauxite settle to the bottom appropriately.
After aluminum hydrate desolvation in the soda, the extra stuff can be isolated and removed quickly. The additional elements are also known as ballast or red mud. Large hydrate particles can be filtered out from the solution without requiring the complex procedure. For exceeding the water, manufacturers wash, dry and heat up the material. The result of the process is alumina. This substance has an unlimited shelf life. However, it has to be stored under appropriate conditions because it can absorb moisture at the first provided opportunity. Thus, alumina producers choose to ship the material to smelters ASAP. Manufacturing system stack the metal into piles that weight about 30,000 tones. As a result, a kind of layered pie about ten meters high is built. The mass is then cut and loaded into the railroad for dispatching to smelters to create the material suitable for producing aluminum sheets and other products such as aluminium sidings for cladding.
Sintering is another method for alumina production, which is less common in comparison to the Bayer system. The technique is about making solid materials from powders at high temperature. The primary element is sintered with lime and soda. The latter two parts generally bind the silica into inexplicable silicates that can then be easily separated from the produced alumina. This method is suitable for obtaining alumina from a high content of toxic silica admixture bauxite. However, sintering can consume more energy in comparison to the Bayer process.
Alumina is considered the direct source of material in the pure aluminum production procedure. However, Cryolite is another component that is necessary to create the right environment for electrolysis. This substance is a rare natural fluoride mineral that is manufactured in artificial ways due to its scarcity. In modern industries, Cryolite is made by mixing up hydrofluoric acid with soda and aluminum hydroxide.
In part two of How is the Pure Aluminum Produced, more details are about the production procedure is introduced.