BHP Billiton Interview Questions and Answers

Alumina is obtained from bauxite through the Bayer process.

• Bauxite is crushed and mixed with sodium hydroxide to form a slurry.

• The slurry is heated and pressurized in a digester to dissolve the alumina content.

• The resulting solution is cooled and filtered to remove impurities.

• The purified solution is then heated to precipitate the alumina as a white powder.

• The alumina powder is washed, dried, and calcined to produce pu...read more

The reaction for Al extraction from alumina involves the reduction of alumina using carbon or electrolysis.

• Alumina (Al2O3) is first converted into aluminum chloride (AlCl3) by reacting with hydrochloric acid.

• The aluminum chloride is then reduced to aluminum metal by either carbon reduction or electrolysis.

• In carbon reduction, carbon (usually in the form of coke) is heated with the aluminum chloride to produce aluminum ...read more

There are four main types of cast iron: gray iron, white iron, ductile iron, and malleable iron.

• Gray iron is the most common type and has excellent castability and good machinability.

• White iron is very hard and brittle, often used for wear-resistant applications.

• Ductile iron has high strength and ductility, making it suitable for a wide range of applications.

• Malleable iron is heat-treated to improve its strength and du...read more

Mining is the process of extracting valuable minerals or other geological materials from the earth's surface or underground.

• Mining is done to obtain various resources such as coal, gold, diamonds, and metals like iron, copper, and aluminum.

• It involves the removal of soil, rocks, and other materials to access the desired minerals.

• Mining can be categorized into surface mining and underground mining, depending on the loca...read more