Converting is a type of metallurgical
smelting
Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
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. The vessel used was called the ''Bessemer converter''. Modern steel mills use
basic oxygen process
Basic oxygen steelmaking (BOS, BOP, BOF, or OSM), also known as Linz-Donawitz steelmaking or the oxygen converter processBrock and Elzinga, p. 50. is a method of primary steelmaking in which carbon-rich molten pig iron is made into steel. Blowin ...
converters.
Equipment
The converting process occurs in a ''converter''. Two kinds of converters are widely used: horizontal and vertical.
Horizontal (which are an improvement of the ) prevail in the
metallurgy
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the sc ...
of
non ferrous metals
In metallurgy, non-ferrous metals are metals or alloys that do not contain iron (allotropes of iron, Ferrite (iron), ferrite, and so on) in appreciable amounts.
Generally more costly than ferrous metals, non-ferrous metals are used because of d ...
. Such a converter is a horizontal barrel lined with refractory material inside. A hood for the purpose of the loading/unloading operations is located on the upper side of the converter. Two belts of
tuyeres
A tuyere or tuyère (; ) is a tube, nozzle or pipe through which air is blown into a furnace or hearth.W. K. V. Gale, The iron and Steel industry: a dictionary of terms (David and Charles, Newton Abbot 1972), 216–217.
Air or oxygen is inj ...
come along the axis on either sides of the converter.
Molten sulfide material, referred to as
matte
Matte may refer to:
Art
* paint with a non-glossy finish. See diffuse reflection.
* a framing element surrounding a painting or watercolor within the outer frame
Film
* Matte (filmmaking), filmmaking and video production technology
* Matte p ...
, is poured through the hood into the converter during the operation of loading. Air is distributed to tuyeres from the two tuyere collectors which are located on opposite sides of the converter. Collector pipes vary in diameter with distance from the connection to air supplying trunk; this is to provide equal pressure of air in each tuyere.
This high temperature
roasting
Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelization ...
allows oxygen in the air to replace sulfide compounds in the minerals. Unless carefully captured, these oxidized sulfur compounds such as
sulfur trioxide leave the converter as a noxious acidic vapor, along with other dangerous volatile elements such as
arsenic trioxide
Arsenic trioxide, sold under the brand name Trisenox among others, is an inorganic compound and medication. As an industrial chemical, whose major uses include in the manufacture of wood preservatives, pesticides, and glass. As a medication, i ...
.
See also
*
Smelting
Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
References
{{Chem-stub
Metallurgical processes