The addition of sulphur, and close control over the degree of addition, is an important step in the steelmaking process. There is various ways to add sulphur into steel melt. Usually the sulphur is added in steel melt (temperature 1500 - 1600°C) the form of stick sulphur which is, essentially, elemental sulphur. From experience it has been determined that recovery of about 40 - 50% can be expected from stick sulphur. The non-recovered sulphur easily ignites in air to form sulphur dioxide, a noxious gas with a strong, pungent objectionable odor. Since the density of the stick sulphur (2.08 gm/cc) is low and the boiling point (444.72°C) is also low. this sulphur vapor generation, and subsequent sulphur dioxide fume generation, occurs before molten steel reactions involving sulphur can reach completion. As those skilled in the art will appreciate. the steel reactions are essentially the formation of Mn S in the steel which is non-odorous coupled with the vaporization of uncombined sulphur, which vaporization causes environmental conditions to become very objectionable.
Whereas in cored wire Injection system the recovery of sulphur is 60 - 70% with precise control of composition. In sulphur cored wire, sulphur is encapsulated in steel sheath, when injected into steel it can go in depth of steel melt as shown in figure, where due to sufficient ferrostatic pressure. sulphur bubbles slowly raise to surface and react efficiently in steel melt and also control of wire feeding with help of wire feeder at desired speed ensures high recovery, precise composition control and less fumes generation. Thus the cored wire injection into the steel is environmental friendly due to less fumes generation and economical due to high recovery and less heat rejection.