All About Alumina

Aluminum oxide, more commonly known as alumina, comes from an ore found in tropical and subtropical regions. Since the late 19th century, it has become a key component in many industries. Read on to learn more information about this impressive material.

Description

Aluminum oxide is a chemical compound that consists of aluminum and oxygen molecules. It is refined from bauxite and generally looks like a white powder. It is also known as aloxide, aloxite, or alundum.

Additionally, aluminum oxide can occur in nature as the mineral corundum. This mineral can form into rubies and sapphires. In other words, natural aluminum oxide can produce two of the four precious gemstones.

Production

Manufacturers use the four-step Bayer process to produce this material. First, the bauxite is crushed, washed, dried, and dissolved in a caustic soda at high temperatures. Next, it is filtered to remove any impurities. The producers then put the remaining solution into tall tanks. In these tanks, producers add aluminum hydroxide seeds while the solution starts to cool. These cause solid aluminum hydroxide pieces to form in the solution. They settle at the bottom of the tank and are removed after it has cooled. These pieces are washed and reheated. After this, aluminum oxide emerges as a fine white powder. It looks like sugar but is hard enough to scratch glass.

This process was invented in 1887 by Carl Josef Bayer. He designed this as a way to supply the powder to the textile industry. His process gained popularity and importance when it was combined with the Hall-Heroult electrolyte process. These additional steps created aluminum. Today the Bayer process is still used for producing aluminum oxide.

Uses

In addition to being necessary for the production of aluminum, aluminum oxide has other industrial uses. For instance, it is often used as a filler for plastics. Additionally, it is used as an abrasive because it is a cheaper alternative to industrial diamonds. In the automobile industry, aluminum oxide is used in paint to give it a reflective sheen. This compound is also necessary for refineries where it is used to convert the dangerous waste gas hydrogen sulfide into sulfur. Aluminum oxide is also used to synthetically produce sapphires and rubies.

Masquerading under a variety of names, aluminum oxide is derived from the Bayer process. Although it is often used in the production of aluminum, aluminum oxide has become important in a variety of industries.