Question

Which of the following statements regarding Kroll's process is incorrect?

• A. Reduction is done only by sodium
• B. Reduction chamber should be free of oxygen
• C. It is used for extraction of titanium and zirconium
• D. Pure metal chloride serves as main raw material

Hint:

Remember the key features of the Kroll Process:

• Metals: Ti, Zr

• Raw Material: Metal Chloride (e.g., TiCl\(_4\))

• Reductant: Magnesium (Mg)

• Atmosphere: Inert (Argon)

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The Kroll process is the primary industrial pyrometallurgical method for producing reactive metals like titanium (Ti) and zirconium (Zr). The process involves the reduction of the metal's chloride with a more reactive metal in an inert atmosphere.

Step 2: Detailed Explanation:
Let's evaluate each statement:

• (A) Reduction is done only by sodium: This statement is

incorrect. The most commonly used reducing agent in the Kroll process for titanium is molten

magnesium (Mg). While sodium (Na) can also be used (in a similar process called the Hunter process), magnesium is commercially dominant. The claim that it is done "only by sodium" is false. The reaction is: \( \text{TiCl}_4(g) + 2\text{Mg}(l) \rightarrow \text{Ti}(s) + 2\text{MgCl}_2(l) \).

• (B) Reduction chamber should be free of oxygen: This is

correct. Titanium and zirconium are highly reactive at the process temperatures (800-850°C) and would readily react with oxygen or nitrogen from the air. Therefore, the reaction must be carried out in an inert atmosphere, typically argon.

• (C) It is used for extraction of titanium and zirconium: This is

correct. The Kroll process is the main production route for these two metals.

• (D) Pure metal chloride serves as main raw material: This is

correct. The process starts with a highly purified liquid metal chloride, such as titanium tetrachloride (TiCl\(_4\)).


Step 3: Final Answer:
The incorrect statement is that the reduction is done only by sodium, as magnesium is the primary reducing agent used commercially.