The process of making aluminium

Two steps are involved in the production of aluminium: the Bayer process, which involves processing bauxite ore to produce aluminium oxide, and the Hall-Heroult process, which involves smelting aluminium oxide to produce pure aluminium.


The Bayer method

Bauxite ore is first mechanically crushed. After that, caustic soda is added to the crushed ore, which is then ground in a mill to create a slurry (a watery suspension) that contains incredibly small ore particles.

2 The slurry is pumped into a digester, a tank with a pressure cooker-like function. Under a pressure of 50 lb/in 2, the slurry is heated to 230–520°F (110–270°C) (340 kPa). These conditions are kept in place for anywhere between 30 minutes and several hours. If necessary, more caustic soda may be added to guarantee the complete dissolution of all aluminum-containing compounds.

3 A series of flash tanks are used to lower the pressure and recover heat that can be used again in the refining process as the hot slurry, which is now a sodium aluminate solution, passes through them.

4 A settling tank is pumped with the slurry inside. Impurities that the caustic soda cannot dissolve settle to the bottom of the tank as the slurry sits there. One manufacturer compares this process to fine sand that settles to the bottom of a glass of sugar water. Just as the aluminium in the settling tank stays dissolved in the caustic soda, the sugar does not separate out of the water during this process. Fine sand, iron oxide, and oxides of trace elements like titanium make up the residue (also known as "red mud") that collects in the bottom of the tank.

5 The remaining liquid, which resembles coffee in appearance after the impurities have settled out, is pumped through a number of cloth filters. The filters capture any tiny impurities that are still present in the solution. To recover reusable alumina and caustic soda, this material is washed.

6 The filtered liquid is pumped through a set of precipitation tanks that are six stories tall. Each tank's top is used to add alumina hydrate seed crystals, which are alumina molecules bound to water. As the seed crystals move through the liquid and alumina that has been dissolved adheres to them, they grow.

7 Crystals are removed when they precipitate (settle to the tank's bottom). They are moved to a kiln for calcining after being washed (heating to release the water molecules that are chemically bonded to the alumina molecules). Crystals are fed continuously into a rotating, cylindrical kiln that is tilted to allow the material to pass through it using gravity using a screw conveyor. Anhydrous (waterless) alumina crystals are left after the water molecules are driven away at a temperature of 2,000 °F (1,100 °C). The crystals move through a cooler after leaving the kiln.

KMC Aluminium is the Best Aluminium Company In Chennai & provide best aluminium at affordable price..