If Na 2 CO 3 is used to obtain alumina from Bauxite, process is known as-

Question

If Na 2 ​ CO 3 ​ is used to obtain alumina from Bauxite, process is known as-

TestHub · Accepted Answer

The correct option is (A) Hall's method.

Hall's method is a chemical leaching process used to purify bauxite ore, specifically when it contains silica (SiO₂) as the main impurity.

In this process, the finely powdered bauxite ore is fused with sodium carbonate (Na₂CO₃) to form soluble sodium aluminate (NaAlO₂). The reaction is given as:

$A l_{2} O_{3} \cdot 2 H_{2} O + N a_{2} C O_{3} \to 2 N a A l O_{2} + C O_{2} ↑ + 2 H_{2} O$

The mass is then dissolved in water, filtered, and treated with CO₂ gas to precipitate aluminum hydroxide, which is calcined to obtain pure alumina (Al₂O₃).

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