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A water jacket furnace can be used to reduce non-ferrous oxide ores mixed with coke, to produce metal and slag. When smelting lead, the feedstock is lead oxide, coke and fluxes. When smelting lead sulphide ores, the ore is first sintered to form a lead oxide sinter. Lead and silver ores often occur in the same ore body.
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 .
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.
In operation, after the bloomery is heated typically with a wood fire, shifting to burning sized charcoal, iron ore and additional charcoal are introduced through the top. Again, traditional methods vary, but normally smaller charges of ore are added at the start of the main smelting sequence, increasing to larger amounts as the smelt progresses.
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.
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.
Direct reduction processes can be divided roughly into two categories: gas-based and coal-based. In both cases, the objective of the process is to remove the oxygen contained in various forms of iron ore (sized ore, concentrates, pellets, mill scale, furnace dust, etc.) in order to convert the ore to metallic iron, without melting it (below 1,200 °C (2,190 °F)).