Aluminium History

In the ancient history aluminium was used as a compound of metals. The aluminium compound was used in pottery by Persians. Also, the Egyptians used aluminium compounds in fabric dyes, cosmetic and medicines. The aluminium was used as compound due to the difficulty of extracting it as a pure metal.

In 1886 a process was created and developed by two scientists. The process aimed to isolate aluminium from its compound. The process was called the Hall-Heroult process, named after the persons who created this process. In 1888, another process called the Bayer process was created to refine the aluminium from its ore. The creation of these processes made the production of aluminium economical.

Aluminium now is a very famous metal due to its properties. Aluminium is non-magnetic and non-toxic. Also, aluminium can keep its shape under extreme cold without being brittle. Aluminium also does not rust and can conduct electricity and heat. Aluminium also is lightweight, workable and can be economically recycled.

Nowadays, you can find aluminium in many applications. It is used in cooking equipment, food packaging and drink cans. Also, it is used in flying transportation because of its lightweight. There are some electrical uses for aluminium due to its conductivity. Because aluminium has a resistance to corrosion, it is used also in buildings.

Bayer Process

After the creation of Bayer process, it has become the primary method for refining alumina. The Bayer process is composed of five steps. The steps can be described like the following series: mixing, digestion, clarification, precipitation and calcination.

First, the crushed ore is mixed with caustic soda in a grinding mill machine. Then, the produced slurry is pumped to a digester. The slurry is heated in the digester to 110-270 degrees for several hours to dissolve the aluminium compounds. After that, the slurry is transferred to a flash tank which reduces the pressure and recovers the heat.

Next, the slurry is pumped to a clarification tank where the impurities can settle at the bottom of the tank. Then, the liquid is pumped to a filter. Now any unwanted impurities are trapped by the filter. The bauxite residue in the clarification tank is taken and filtered to catch any useful residue. Then the remaining residue which called the “red mud” is transferred to a disposal pond. Next, the filtered liquid is moved to precipitation tanks.

In the tanks, seed crystals of alumina hydrate are added from the top of each tank. The crystals attract and attach the dissolved alumina to them while they precipitates. Then, the precipitated crystals are moved to a kiln. The kiln heats the crystals to isolate the alumina from the water molecules. Finally, the dry powder produced is shipped to aluminium smelter factory.