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Direct reduction is the fraction of iron oxide reduction that occurs in a blast furnace due to the presence of coke carbon, while the remainder - indirect reduction - consists mainly of carbon monoxide from coke combustion. It should also be noted that many non-ferrous oxides are reduced by this type of reaction in a blast furnace.
Plants for the production of pre-reduced iron ore are known as direct reduction plants. The principle involves exposing iron ore to the reducing action of a high-temperature gas (around 1000 °C). This gas is composed of carbon monoxide and dihydrogen, the proportions of which depend on the production process.
In old movies and stories, when there is a description of suicide by "turning on the gas" and leaving an oven door open without lighting the flame, the reference was to coal gas or town gas. As this gas contained a significant amount of carbon monoxide it was quite toxic. Most town gas was also odorized, if it did not have its own odor.
The blast furnace process is a typical example of a process of reduction of metal from ore with carbon monoxide. Likewise, blast furnace gas collected at the top of blast furnace, still contains some 10% to 30% of carbon monoxide, and is used as fuel on Cowper stoves and on Siemens-Martin furnaces on open hearth steelmaking.
Blast furnace gas (BFG) [1] is a by-product of blast furnaces that is generated when the iron ore is reduced with coke to metallic iron. It has a very low heating value , about 3.5 MJ/m 3 (93 BTU /cu.ft), [ 2 ] because it consists of about 51 vol% nitrogen and 22 vol% carbon dioxide , which are not flammable.
Carbothermal reactions produce carbon monoxide (CO) and sometimes carbon dioxide (CO 2). The facility of these conversions is attributable to the entropy of reaction: two solids, the metal oxide (and flux) and carbon, are converted to a new solid (metal) and a gas (CO x), the latter having high entropy.
Mix of carbonic oxide (carbon monoxide, CO), marsh gas (methane, CH 4), hydrogen (H 2), a small quantity of simple hydrocarbon illuminants, along with small quantities of nitrogen and carbon dioxide. 330–400 > 8: Earliest processes from 1895, came into industrial-scale use by 1918 (Meade, p. 766–769).
For instance, in a high temperature reducing environment, such as that created for the reduction of iron oxide in a blast furnace or the preparation of carburizing atmospheres, [5] carbon monoxide is the stable oxide of carbon. When a gas rich in CO is cooled to the point where the activity of carbon exceeds one, the Boudouard reaction can take ...