Smelting is the general term for getting a metal from its natural ore. Gold is an exception, because it is usually found as a pure metal. Other metals, like iron, copper, zinc, and silver, need to be got from their ore.
The process of smelting always involves heating the ore, and may also use a reducing agent like coke or charcoal. Most ores are oxides and this process removes the oxygen from the oxide, leaving behind the metal. The metal is still not pure, so then another process is needed. A flux is added, to clean and purify the metal. Limestone is the usual flux for this purpose. It removes the impurities as slag.
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Smelting Facts for Kids. Kiddle Encyclopedia.