Chloridizing

Chloridizing is a metallurgical process used to convert metal oxides or sulfides into metal chlorides. This is often an intermediate step in the extraction or purification of metals. The process typically involves heating the ore or concentrate with a chlorinating agent, such as chlorine gas, hydrogen chloride, or a metal chloride. The choice of chlorinating agent and reaction conditions depends on the specific metal and its compound. For example, in the extraction of aluminum, alumina (aluminum oxide) is reacted with chlorine in the presence of carbon to form aluminum chloride. This method is less common than the Hall-Héroult process but has been explored. Similarly, chloridizing is used in the processing of certain refractory gold ores where the gold is present as tellurides or encapsulated within sulfide minerals. Chlorination can liberate the gold, making it available for subsequent cyanide leaching. Another application is in the removal of impurities, such as sulfur or arsenic, from metal concentrates by converting them into volatile chlorides that can be driven off as gases. The resulting metal chlorides can then be further processed, for instance, by electrolysis or reduction, to obtain the pure metal.