| Sulfur is a harmful element in most steel, one of whose main harm can cause hot shortness. The level of lime activity is directly related to the amount of sulfur in steel.Iso-distribution ratio diagram of sulfur and isothermal section diagram of slag system Ca O-Si O2-Fe O-Mg O?10%?-Mn O?7%? are drawed by Factsage software. The theoretical slag formation path is obtained. Limestone is calcined with pressure vacuum resistance furnace and active lime is prepared. Activity of lime is determinated. Melting temperature and DSC curve are respectively determinated by melting point melting speed apparatus and high temperature comprehensive thermal analyzer. Effect of slagging speed of active lime with different activity degree on desulfurization is compared. The results are as follows:1) When CaO content is certain, LS increases gradually with increasing Fe O/Si O2ratio; When Fe O content is constant, Ls increases with the increase of basicity; When basicity is constant, Ls increases with the increase of Fe O content in low alkalinity range and Ls decreases with the increase of Fe O content in high alkalinity range;2) As to the theoretical slag formation path, the iron desulfurization slag formation path AB with sulfur distribution ratio increasing most quickly should be choosed. A point of slag composition is 18.6%Ca O-36.9%Si O2-44.5%Fe O with melting point 1241? and LS 0.9. B point of slag composition is 58.7%Ca O-16.8%Si O2-24.5%Fe O with melting point 1607?;3) When alkalinity is certain, melting temperature under the same shrinkage rate decreases with activity increasing. When activity is certain, melting temperature under the same shrinkage rate first decreases and then increases; Desulphurization of the lime with 417 m L is best because of low melting temperature. Under this experimental conditions, when ratio between iron and slag is 100:13, desulfurization effect is best,with desulphurization rate 95.3%. |
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