Which metallurgical process involves the use of heat energy?

The process you're referring to is pyrometallurgy, which encompasses any metallurgical treatment involving high-temperature processes. This method relies on the application of heat to extract metals from their ores or to refine them. Pyrometallurgy typically includes operations such as smelting, roasting, and refining, which all require substantial heat energy to facilitate reactions that separate metal from its ore or to remove impurities.

Heat plays a crucial role in breaking down metal compounds and enabling the transformation of raw materials into metallic forms. The temperature range can vary greatly, depending on the type of metal being processed and the specific reactions involved. Since pyrometallurgy often occurs at temperatures exceeding those used in other metallurgical processes, it is particularly effective for extracting metals like iron, copper, and lead.

Other metallurgical processes listed either do not primarily rely on heat (like electrolysis, which uses electric current to drive a non-spontaneous reaction) or utilize it to a lesser extent (like hydrometallurgy, which generally involves aqueous solutions at lower temperatures).