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About aluminium

Most people are familiar with the designation Al in the periodic table. It stands for the silvery-white, lightweight metal aluminium. The chemical element does not occur in natural form because it is a base metal. It’s the most common metal in the Earth’s crust, at approx. 8 percent. Yet it was only discovered around 200 years ago. Aluminium occurs mostly in the form of aluminium ore in various compounds. It is extremely versatile and easy to work.

In materials technology, all materials based on the element Al are categorised as aluminium. That covers the following types:  

  • Ultra-pure aluminium  
  • Pure aluminium  
  • Primary aluminium 
  • Secondary aluminium 
  • Aluminium alloys 

What are the different types of aluminium?

Currently there are around 200 different aluminium alloys. The various alloy contents create different characteristics regarding rigidity, formability and weldability. So one aluminium is not necessarily the same as another. Depending on the specific requirements, different aluminium alloys are used. Find out here about our variety of alloys.

Pure aluminium

contains at least 99 percent aluminium and is also termed primary aluminium. It is the starting material for aluminium alloys as well as ultra-pure aluminium. Pure aluminium has a high level of purity and must not contain more than 0.1 to 1.0 percent by weight of contaminants or other alloy elements. Ultra-pure aluminium has an even higher purity level. It contains at least 99.9 percent aluminium. 

Primary aluminium

is produced from aluminium oxide by means of fused-salt electrolysis. The aluminium oxide is extracted from bauxite. Therefore primary aluminium is defined as the initial pure aluminium material produced from bauxite. 

Secondary aluminium

is aluminium gained by recycling old and new scrap by melting in castings. Here the metal does not come directly from bauxite, but is a recycling product  fed back into the economic cycle. The major benefits are the energy savings and eco-friendliness of the process. This is because recycling requires only about 4 to 6 percent of the energy used for primary aluminium production. 

Production of aluminium

Aluminium and aluminium alloys are produced from the ore-bearing mineral bauxite. First the Bayer process is applied in a smelting plant to gain aluminium oxide. Next, a fused-salt electrolysis stage named the Hall-Héroult process produces pure aluminium from the aluminium oxide.  

Recycling consumes drastically less energy than the complex, energy-intensive production process for primary aluminium. Secondary aluminium in the required alloy form is produced in the casting by melting aluminium scrap. It makes no difference whether the scrap is old or new. During this process, the alloy components are precisely controlled. By adding alloying elements such as copper, magnesium, manganese, nickel or zinc, the material properties are tailored to particular applications and to customer specifications. STEP-G also offers a comprehensive variety of alloys. You can find an overview here.