Effect of Propane Gas on Hot Metal Desulfurization by CaO Based Flux

The effect of propane gas blowing on hot metal desulfurization was investigated in laboratory-scale experiments and commercial plant tests. Desulfurization tests were carried out by two methods, flux injection and mechanical stirring. Flux injection: In the 4 ton-scale and commercial-scale tests, the flux efficiency for desulfurization increased by 1.2–1.7 times by mixing of propane gas with the nitrogen carrier gas at propane gas ratio of 10–58%. The effect of propane gas mixing on improving desulfurization efficiency is presumed to be caused by a decrease in the local oxygen potential, together with an increase in the interfacial area between hot metal and flux. Mechanical stirring: A top-blowing propane gas technique was examined in both 4 ton-scale tests and commercial hot metal desulfurization operation by mechanical stirring with an impeller. The flux efficiency for desulfurization increased by 1.25 times with top-blowing propane gas. The presumed effects of the top-blowing propane gas are enhancement of stirring energy in addition to reduction of the oxygen potential in hot metal and increase in the interfacial area between hot metal and flux. The sulfur partition ratio between slag and hot metal with mechanical stirring was higher than that with flux injection in a torpedo car at the same oxygen potential level with utilizing propane gas.