subject: Aluminum Fabrication: Learning The Basics [print this page] It takes just a few minutes to empty an aluminum can and toss it in the trash. Because aluminum is so common in everyday settings, many aluminum products and machinery can go unnoticed, and its creation underappreciated.
However, the process behind creating aluminum is long and complicated, and the result is a metal used in many household and industrial products. Before aluminum is ever fitted for laser cutting and fitting, it must undergo a rigorous series of purifications and heating.
How is Bauxite Ore Refined to Create Aluminum?:
Two main processes are typically required for creating aluminum: refining bauxite ore and smelting the resulting aluminum oxide to release the actual aluminum.
The first step, refining, is the most intensive. Bauxite must be mechanically crushed and mixed with caustic soda. When the mix is processed, the result is a type of slurry comprising ore particles. The slurry must then be heated and put under heavy pressure for hours while the aluminum-containing compounds are dissolved.
The resulting product, a sodium aluminate solution, is purified in a settling tank. In the tank, most impurities settle to the bottom, and the remaining liquid is then pumped through cloth filters to remove even more particles.
The liquid then undergoes a chemical process during which "seed crystals" containing alumina hydrate are added to giant precipitation tanks. As the seeds settle in the tank, they bind with dissolved alumina and grow. In the end, those new, larger crystals, are removed, washed and super-heated to remove any remaining water molecules.
What is Smelting?:
Smelting occurs once the water has been removed. The process requires a steel vat, called a reduction pot, with carbon lined along the bottom. Simultaneously, carbon rods are suspended above the pot, helping to create an electric current through molten aluminum mixture.
A current is passed through the aluminum solution, forcing the aluminum and oxygen atoms to separate. The oxygen molecules are attracted to the carbon rods to create carbon dioxide, while the newly freed aluminum sinks to the bottom of the pot.
Is Anything Left Behind Once Aluminum is Created?:
Some of the byproducts of aluminum production are largely useful. A powdery substance filtered out during the refining process can be used in products such as laundry detergents, toothpaste and fluorescent light bulbs. It can also be used for ceramics and electronics finishing.
Other byproducts are formed that are less useful. During the same refining process, a red muddy substance is created, called ore refuse. It comprises iron, titanium and other elements, but it is mostly unusable.
