Question

Titanium extraction commonly involves

• A. Kroll process
• B. Hall process
• C. Bayer process
• D. Mond process

Hint:

The Kroll process is highly energy-intensive and operated in batches because the titanium sponge must be vacuum-distilled to remove excess magnesium and magnesium chloride.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to identify the standard industrial process used for the extraction of metallic titanium.

Step 2: Key Formula or Approach:
Titanium is highly reactive and cannot be reduced by carbon because it easily forms stable titanium carbides.
Instead, the Kroll process relies on the pyrometallurgical reduction of titanium tetrachloride (\( \text{TiCl}_4 \)) using metallic magnesium under an inert argon atmosphere.

Step 3: Detailed Explanation:

• Reaction Steps in the Kroll Process:
1.

Carbothermic Chlorination: Titanium dioxide (rutile ore) is converted to volatile titanium tetrachloride at \( 1000^\circ\text{C} \) in the presence of carbon and chlorine gas:
\[ \text{TiO}_2 + 2\text{C} + 2\text{Cl}_2 \rightarrow \text{TiCl}_4 + 2\text{CO} \]
2.

Purification: The liquid \( \text{TiCl}_4 \) is purified by fractional distillation.
3.

Magnesiothermic Reduction: Highly purified \( \text{TiCl}_4 \) vapor is introduced into a reactor containing liquid magnesium at \( 800^\circ\text{C} \text{ to } 850^\circ\text{C} \) under a protective argon atmosphere:
\[ \text{TiCl}_4\text{(g)} + 2\text{Mg(l)} \rightarrow \text{Ti(s)} + 2\text{MgCl}_2\text{(l)} \]
The resulting titanium is produced as a porous mass called titanium sponge.

• Analysis of Other Options:
-

Hall process (Option B) is the electrolytic reduction process for aluminium.
-

Bayer process (Option C) is the hydrometallurgical purification of bauxite to produce alumina.
-

Mond process (Option D) is the carbonyl process used for refining nickel.


Step 4: Final Answer:
Hence, titanium extraction commonly involves the Kroll process, which corresponds to Option (A).