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Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct ...
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)).
Iron oxide becomes metallic iron at roughly 1250 °C (2282 °F or 1523 K), almost 300 degrees below iron's melting point of 1538 °C (2800 °F or 1811 K). [ 5 ] Mercuric oxide becomes vaporous mercury near 550 °C (1022 °F or 823 K), almost 600 degrees above mercury's melting point of -38 °C (-36.4 °F or 235 K), and also above mercury's ...
In China, these iron working methods spread northward, and by 300 BC, iron was the material of choice throughout China for most tools and weapons. [9] A mass grave in Hebei province, dated to the early 3rd century BC, contains several soldiers buried with their weapons and other equipment. The artifacts recovered from this grave are variously ...
The extraction of iron from its ore into a workable metal is much more difficult than for copper or tin. The process appears to have been invented by the Hittites in about 1200 BC, beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines. [27] [28]
The blast furnace was the next step in smelting iron which produced pig iron. [4] The first blast furnaces in Europe appeared in the early 1200s around Sweden and Belgium, and not until the late 1400s in England. The pig iron poured from a blast furnace is high in carbon making it hard and brittle, making it hard to work with.
Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within the ore, into soluble salts while the impurity remains insoluble.
The best yield of iron achievable from dry puddling is one ton of iron from 1.3 tons of pig iron (a yield of 77%), but the yield from wet puddling was nearly 100%. The production of mild steel in the puddling furnace was achieved circa 1850 [ citation needed ] in Westphalia , Germany and was patented in Great Britain on behalf of Lohage, Bremme ...