Bauxites are received directly from mines. They are being tested for chemical compositions. Due to the fact that the chemical compositions of bauxites vary from site to site or even from batch to batch, they are being blended in correct proportion for a final same or similar content.
Bauxites coming from mines are existed in form of hydrates. They are sent to rotary kiln at high temperature to drive off the water. This process is called bauxite calcination.
Calcined bauxites that are ready to be used are being sent to silo. There are also other raw materials and ingredients being stored in the system. Correct quantities for different raw materials under a recipe are taken and sent to furnace by a mechanical conveyor system.
The temperature inside furnace is as high as 1300 deg. C. All raw materials are melted, reacted and form another mineral crystal. This process is called fusing and it always takes some hours.
When fusing is complete, the molten content is poured into a receiver. Due to extreme high temperature, the content takes few days to cool to form ingots.
The cold ingots are being broken down by different machines into small sizes for further processing.
Breaking down big ingots into smaller grains (finished grits) is a complicated process because they are very hard and there are impurities inside. Different machines like crushers, impurity separators, kilns and sieves are connected as a whole and highly automatic system. Depending on the types of product to get, grains are further receiving temperature treatment, surface treatment, etc.