Metallurgical Engineering is a diverse field that encompasses three main branches: minerals processing, extractive metallurgy and physical metallurgy. These three combined, along with other associated processes, are responsible for the creation and production of virtually all the hundreds of metals and metal alloys used by modern society.
Mineral processing is the process which deals with the extraction of raw ore from the earth and its physical preparation for further processing through extractive metallurgy. Mineral processing basically consists of crushing raw ore down to a sandy consistency through the use of mechanized rock breakers, and then grinding further still into a fine dust which is then taken through the process of concentration. This last step involves mechanically separating the mineral content of ore from raw rock. It's usually done with magnets, which separate ferrous minerals from nonferrous rock; flotation, which separates denser minerals from less dense material; or optical differentiation of colors. Once concentrated, mineral ore is then sent off for extractive metallurgy.
Extractive metallurgy is the process of extracting pure or nearly pure metals from mineral ore that has been processed. The minerals extracted from raw ore during the mineral processing step usually take the form of sulphides, oxides, carbonates, arsenides and silicates and have to be converted into the actual metals they contain through a process of reduction. This reduction can involve a chemical process or an electrolytic one. Both processes can be very complex and, depending on the metals being reduced, can require the use of numerous different chemicals and techniques. However the basics are that chemical reduction requires smelting the minerals with the use of reductive agents like coke and charcoal and then adding purifying chemicals to further extract the metal from the reduction. Electrolysis usually means passing current through a molten metal oxide or a solution containing the mineral and the underlying metal's salt.
Physical metallurgy is the stage at which extracted, purified metals are combined with other metals to form manufacturing-ready alloys and finished products. Engineers often melt different metals together in a process known as alloying, or heat treat a certain metal or alloy to give it the right qualities of hardness, flexibility or magnetism. Often, a metal will be alloyed and heat treated in order to be ready for its final requirements.
Metallurgical Engineering Sub-branches
There are numerous sub-branches under the umbrella of metallurgical engineering and its three main branches. With regards to mineral processing these include pyrometallurgy, or the separation of ore from rock through roasting and other heat treatments and hydrometallurgy, which is the use of water and chemical solutions to leach and reduce minerals from ore. Extractive metallurgy also has its subbranches. For example, ferrous metallurgy is concerned solely with extracting iron from iron ore. Other sub-branches of extractive metallurgy include precious metals such as gold, silver and platinum; light metals such as aluminum, titanium and tin; and base metals extraction, which revolves around lead, zinc and copper.
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