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Oxygen has many important uses within the steel industry, each of them involves the heating and melting of metals. Oxygen is a popular gas used in steel-making, in part due to the continued use of the basic oxygen furnace. Oxygen has a number of common uses in the industry, depending on the furnace under consideration.
Blast furnaces account for up to 40 percent of the total amount of oxygen used in a typical integrated steel mill. Oxygen is injected into these furnaces through spargers--devices used to spray gas into a system--to enrich the air. This process increases the productivity of the furnace. It also serves to lower coke consumption by facilitating the addition of powdered coal and natural gas to the furnace. Using oxygen in a blast furnace lowers the overall cost of production.
Basic Oxygen Furnaces
In basic oxygen furnaces, oxygen is used for decarburization--the process of decreasing the level of carbon in metals--and the conversion of hot metal formed in a blast furnace to liquid steel. This process typically accounts for about half the amount of oxygen used in an integrated steel mill. When oxygen reacts with silicon and carbon, it produces a large amount of heat. This heat is enough to melt scrap metal in large quantities.
Electric Arc Furnaces
Electric arc furnaces have three primary uses for oxygen. Oxygen is used to run oxy-fuel burners used for heating and melting scrap metal. Oxygen is used in high-velocity lancing. High-velocity lancing is used in localized scrap melting processes, decarburization of steel and slag foaming. Oxygen is used in sub-sonic injection processes used for post combustion of carbon dioxide.
Rotary furnaces used to depend on sulfur oxide and nitrogen oxides to heat metal. They have since switched to pure oxygen. Using pure oxygen allows for the avoidance of heat loss, thereby reducing the amount of time the furnace needs to complete tasks as well as its overall costs.
Steel Reheating, Cutting and Burning
Oxygen is used in steel reheating furnaces. In particular, oxygen is used for enrichment or two run oxy-burners, as blast furnaces and rotary furnaces, respectively. Using oxy-fuel burners in this process contributes to reduced fuel consumption when compared to other gases. High-purity oxygen is used in cutting and burning processes to run automatic cutoff torches, as well as in the cutting of crops and other forms of mill scrap.