Bayer Process

First, the bauxite ore is crushed mechanically. Then the slurry is produced by mixing it with caustic soda in a grinding mill.  Then the slurry is pumped into a digester under pressure of 340Kpa and heated to 110-270C. This process takes half an hour to several hours. To be sure all aluminium compounds are dissolved, additional caustic soda may be added.

The hot slurry is passed through a flash tank to lower the pressure and recover heat. Then it is pumped into a clarification tank where impurities settle to the bottom. The residue (called “red mud”) that settles in the bottom of the tank consists of fine sand, iron oxide and oxide of other elements.

After impurities have settled out, the remaining liquid is pumped through a series of cloths filters to be sure no impurities remain. The seed crystals of alumina hydrate are added to a series of precipitation tanks where they attach to dissolved alumina and precipitate. Then the crystals are removed and transferred in to a kiln. Finally, the washed crystals are heated to remove water and leave only dry white alumina crystals.

Aluminium History

Did you know about almuinium??
Test yourself

Where was almuinium found?
What were the uses of almuinium ?
Who invented the main methed of aluminium processing?
Was aluminium price in the 19th cenctury more expansive than sliver?
What are the properties of aluminium?



Aluminium is a silvery white member of the boron group of chemical elements identified in the early 19^th century. It has the symbol Al and the atomic number is 13. Aluminium is the third most aboundant element after oxygen and silicon. It makes up about 8% by width of the Earth’s solid surface. The aluminium compound has been used for many years. Ancient Egyptians and Babylonians used it in cosmetics, fabric dyes and medicines. After discovering it, there were many difficulties to extract it from its ore so, that made it a rare metal and valuable as silver.



In 1886, two scientists independently developed a smelting process that made the economical mass production of aluminium possible. “Hell-Heroult” is the name of this process. Two years later, an Austrian chemist developed the Bayer process for refining aluminium ore from Bauxite.

Aluminium has many properties that make it useful in a wide range of applications. It is lightweight, strong, non-magnetic and non-toxic. It conducts heat and electricity and reflects heat and light. Also, aluminium is 100% recyclable without any loss of its natural qualities.