Question

1. Describe how bauxite is converted to aluminium oxide (Al2O3) via the Bayer process?

2. Describe the Kroll process used to produce metallic titanium. Give the key chemical equation.

3. Give 2 short application examples of the Ellingham diagram in process metallurgy.

4. Name 2 important fields of application of Ti alloys and an alternative processing route that can provide highest purity Ti.

5. What is the main Al ore and where are the world’s largest reserves? Given the fact that these high alumina containing ore bodies might be depleted in 20-30 years, what could be an alternative source?

6. Describe the electro-refining process of copper and give the most important chemical equations.

Answer 1

1)

the bayer process is used to refine bauxite to extract alumina. It contains about 25-65 % of alumina in it.

In Bayer process, bauxite is heated in a pressure vessel about 150-230 C in the presence of caustic soda. At these temperatures, the aluminium is dissolved as sodium aluminate in an extraction process. After separating the residues we get Alumina Hydroxide, which is then cooled and crystallized.

2)

The Kroll process is used to produce metallic titanium. It is a pyrometallurgical process.

The ingredient, refined pure rutile is reduced from petroleum-derived coke at about 1000 C. The mixture is then treated with Chlorine and titanium tetrachloride gas. this mixture is sent to a separation reactor, where titanium chloride is reduced by liquid magnesium.

2 Mg + TiCl₄ = 2MgCl₂ + Ti

3)

it is a graph that shows the temperature-dependent stability of the compound. It is most widely used in metallurgical industries to select best reducing agent for various ores in purification, extraction and grade setting.

4)

Titanium alloys are mostly used in Aerospace and medical applications. Titanium alloys are light in weight so, using it for aerostructures enhances fuel efficiency. In medical applications, It is used as an implant for replacing fractured bones. titanium alloys are light in weight and comfortable with body fluids, won't react or corrode. kroll process is popular for producing Titanium.

5)

Bauxite is the main aluminium ore and Guinea has the world’s largest bauxite reserves and is the biggest exporter. in overall production, Australia is leading.

6)

In an electrorefining process, the anode is considered an impurity metal, impurities must be driven out to get pure metal. It eliminates unwanted impurities.