Question

For what cupellation process is used?

Answer 1

Cupellation process is used for refining metals where impurities oxidize more easily than the metal itself.

1. The impure metal, often silver containing lead impurity, is heated in bone ash crucibles called cupels.
2. A blast of air oxidizes impurities (e.g., lead to lead oxide) which are removed, leaving behind pure metal.
3. Primarily used for purifying silver by removing lead impurities through oxidation and air blowing.