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Smelting involves more than just melting the metal out of its ore. Most ores are the chemical compound of the metal and other elements, such as oxygen (as an oxide), sulfur (as a sulfide), or carbon and oxygen together (as a carbonate). To extract the metal, workers must make these compounds undergo a chemical reaction.
The mining water contains copper salts in the form of copper sulfate CuSO 4. The iron then reacts with the copper, displacing it from the sulfate ions, causing the copper to precipitate onto the iron sheets, forming a "wet" powder. Finally, the precipitated copper is collected and refined further through the traditional smelting process.
The copper ions are liberated from the residue with sulfuric acid. The barred (denuded) sulfuric acid recycled back on to the heaps. The organic ligands are recovered and recycled as well. Alternatively, the copper can be precipitated out of the pregnant solution by contacting it with scrap iron; a process called cementation. Cement copper is ...
In one of the previous melting stages, lead was added. Gold and silver preferentially dissolved in this, thus providing a means of recovering these precious metals. To produce purer copper suitable for making copper plates or hollow-ware, further melting processes were undertaken, using charcoal as fuel. The repeated application of such fire ...
High-purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots. [49] Lower-purity scrap is melted to form black copper (70–90% pure, containing impurities such as iron, zinc, tin, and nickel), followed by oxidation of impurities in a converter to form blister copper (96–98% pure), which is then refined as ...
A penny, on its face, is worth one cent. $0.01 U.S. dollars. On the other hand, that same penny -- if melted down for the copper it contains -- could be worth quite a bit more.
The process used at the Lünen smelter involves charging the furnace with copper residues and scrap containing between 1 and 80% copper and then melting it in a reducing environment. This produces a "black copper phase" and a low-copper silica slag. Initially the black copper was converted to blister copper in the ISASMELT furnace. [57]
Vacuum arc remelting (VAR) is a secondary melting process for production of metal ingots with elevated chemical and mechanical homogeneity for highly demanding applications. [1] The VAR process has revolutionized the specialty traditional metallurgical techniques industry, and has made possible tightly controlled materials used in biomedical ...