Smelting makes use of heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving just the metal base behind.
The reducing agent is commonly a source of carbon such as coke, or in earlier times charcoal.
The carbon (or carbon monoxide derived from it) removes oxygen from the ore, leaving behind the elemental metal.
The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide.
Fluxes are used in smelting for several purposes, chief among them catalyzing the desired reactions and chemically binding to unwanted impurities or reaction products.
Calcium oxide, in the form of lime, was often used for this purpose, since it could react with the carbon dioxide and sulfur dioxide produced during roasting and smelting to keep them out of the working environment.
The reducing agent is commonly a source of carbon such as coke, or in earlier times charcoal.
The carbon (or carbon monoxide derived from it) removes oxygen from the ore, leaving behind the elemental metal.
The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide.
Fluxes are used in smelting for several purposes, chief among them catalyzing the desired reactions and chemically binding to unwanted impurities or reaction products.
Calcium oxide, in the form of lime, was often used for this purpose, since it could react with the carbon dioxide and sulfur dioxide produced during roasting and smelting to keep them out of the working environment.
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