Heating pyrites to remove sulphur is called:

The correct answer is option D,roasting i.e. heating pyrites like iron pyrite, cu pyrite in presence of air/O₂ is called roasting. The reaction can be shown as follows:

2Cu₂S + 3O₂ →2Cu₂O + 2SO₂

While option A i.e. smelting is a part of benefaction, option B i.e. calcination is for carbonate ores and option C , liquation is a process of purification.

Hence, the correct answer is option D.