Today's KNOWLEDGE Share #Aluminum

 Today's KNOWLEDGE Share

#Aluminum is one of our most widely-used metals, found in everything from beer cans to airplane parts.However, the lightweight metal doesn’t occur naturally, and producing it is a complex process.Each year, the world produces around 390 million tonnes of bauxite rock, and 85% of it is used to make aluminum.

Bauxites are rocks composed of aluminum oxides along with other minerals and are the world’s primary source of aluminum. After mining, bauxite is refined into alumina, which is then converted into aluminum.

Therefore, aluminum typically goes from ore to metal in three stages.

Stage 1: Mining Bauxite

Bauxite is typically extracted from the ground in open-pit mines, with just three countries—Australia, China, and Guinea—accounting for 72% of global mine production.

Country2021 Mine Production of Bauxite (tonnes) % of Total

Australia  110,000,000 28.2%

China  86,000,000 22.1%

Guinea  85,000,000 21.8%

Brazil  32,000,000 8.2%

India  22,000,000 5.6%

Indonesia  18,000,000 4.6%

Russia  6,200,000 1.6%

Jamaica  5,800,000 1.5%

Kazakhstan  5,200,000 1.3%

Saudi Arabia  4,300,000 1.1%

Rest of the World  15,500,000 4.0%

Total 390,000,000 100.0%

Australia is by far the largest bauxite producer, and it’s also home to the Weipa Mine, the biggest bauxite mining operation globally.

Stage 2: Alumina Production

In the 1890s, Austrian chemist Carl Josef Bayer invented a revolutionary process for extracting alumina from bauxite.

Here are the four key steps in the Bayer process:

Digestion:

Bauxite is mixed with sodium hydroxide and heated under pressure. At this stage, the sodium hydroxide selectively dissolves aluminum oxide from the bauxite, leaving behind other minerals as impurities.

Filtration:

Impurities are separated and filtered from the solution, forming a residue known as red mud. After discarding the mud, aluminum oxide is converted into sodium aluminate.

Precipitation:

The sodium aluminate solution is cooled and precipitated into a solid, crystallized form of aluminum hydroxide.

Calcination:

The aluminum hydroxide crystals are washed and heated in calciners to form pure aluminum oxide a sandy white material known as alumina.

The impurities or red mud left behind in the alumina production process is a major environmental concern.

Source:.visualcapitalist

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