The process of heating a carbonate ore in the absence of air to convert it into metal oxide is indeed called Calcination.
Calcination is a thermal treatment process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide. This process involves the decomposition of the carbonate ore, releasing carbon dioxide (CO₂) and leaving behind the metal oxide.
The general equation for calcination is:
M₂CO₃ → 2MO + CO₂
Where M is a metal, such as calcium, magnesium, or zinc.