Study On External Desulfurization Of Hot Iron By Dolomite-based Desulfurizer

External desulfurization of hot iron as one of the steel production process has a great impact on the quality of steel products. Since the1930s, lots of technologies of external desulfurization and desulfurizer have been presented. Because of many advantages of magnesium, magnesium-based desulphurizer and magnesium-based complex desulphurizer are applied widely. However magnesium, as a desulphurizer, has some defects, such as high cost, higher steam pressure, so obtaining a new desulphurizer to replace magnesium-based desulphurizer has become a hot issue worldwide.Based on the principle of pidgeonprocess, a new technology that the magnesium vaper produced in-situ by silicothermic reduction of dolomite and ferrosilicon at the high temperature of hot iron react with sulfur in the hot iron for desulfurization has been presented. The study on some basic problems of this new technology includes the calculation of thermodynamics and the research on kineticsof the related reaction in desulfurization process, experiment of generating magnesium vapor in hot iron temperature environment and desulfurization of hot iron.(1) The results of thermodynamic calculation on three different reducers show that; ferrousilicon and dolomite, as new desulfurizer, was confirmed to be feasible.When the pressure of magnesium vaper is blow0.26atm, reduction will happen at1400℃;(2) On the date of DSC, the differences in the dynamics of several reducing agents have been compared, the activation energy of the reaction of reducing dolomite by ferrousilicon, E, is3638.17kJ/mol, reaction order, n, is2.13. This activation energy is higher than it of the reaction of reducing dolomite by aluminium, and little higher than it of the reaction on pure substances simultaneously.(3) It is confirmed that the magnesium could be produced in the desulfurization. The activation energy of dolomite ferrosilicon reduction was about33.4kJ/mol.The reaction process was controlled by diffusion.(4) The experimental results of desulphurization of hot iron indicate that it is feasible to desulphurize externally in hot iron by magnesium vapor produced in-situ by silicothermic reduction of dolomite and ferrosilicon and to achieve the aim of ultra-deep desulfurization. Desulfurization effect becomes better with adding more desulfurizer.However,with reactiontime,the effect got better at the first15min,but then resulfurization happened.firstly becomes better with time but after15min, then happens. Resulfurization can be restrained by adding the covering agent of CaO at1400℃, the best desulfurization was95.21%, and the lowest sulfur concentration after desulfurization was21ppm.This new method of external desulphurization of hot iron with dolomite-based desulfurizer which is reducted by ferrosilicon is feasible. Raw material of this desulfurizer is very universal, cheap and able to achieve ultra-deep level.The research could provide valuable date for future research.