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16th century cupellation furnaces (per Agricola). Cupellation is a refining process in metallurgy in which ores or alloyed metals are treated under very high temperatures and subjected to controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore.
Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. [1] It is a form of extractive metallurgy that is used to obtain many metals such as iron , copper , silver , tin , lead and zinc .
In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining the final material is chemically identical to the raw material.
Converting is a type of metallurgical smelting that includes several processes; the most commercially important form is the treatment of molten metal sulfides to produce crude metal and slag, as in the case of copper and nickel converting. A now-uncommon form is batch treatment of pig iron to produce steel by the Bessemer process.
These higher production costs made mining and smelting anything but the highest grade silver ores prohibitively expensive, just as the availability of high grade ores was in decline. [5] Bartolomé de Medina initially focused his attentions on learning about new smelting methods from smelters in Spain.
Sinter roasting involves heating the fine ores at high temperatures, where simultaneous oxidation and agglomeration of the ores take place. For example, lead sulfide ores are subjected to sinter roasting in a continuous process after froth flotation to convert the fine ores to workable agglomerates for further smelting operations.
Iron smelting—the extraction of usable metal from oxidized iron ores—is more difficult than tin and copper smelting. While these metals and their alloys can be cold-worked or melted in relatively simple furnaces (such as the kilns used for pottery ) and cast into molds, smelted iron requires hot-working and can be melted only in specially ...
Historically, the reduction of iron ore without smelting is the oldest process for obtaining steel. Low-temperature furnaces, unable to reach the melting temperatures of iron alloys, produce a bloom, a heterogeneous agglomerate of metallic iron more or less impregnated with carbon , gangue , and charcoal .