Calcination and roasting are metallurgical processes. Calcination involves heating ores (like carbonates) in absence of air to remove volatile matter, e.g., $\mathrm{CaC}{O}_3\to \mathrm{CaO}+C{O}_2$. Roasting involves heating sulphide ores in air to convert them to oxides, e.g., $2\mathrm{ZnS}+3O_2\to 2\mathrm{ZnO}+2S{O}_2$. Both require controlled heating and are best performed in a reverberatory furnace, which allows for efficient heat application and gas control.

Final Answer: reverberatory furnace