Copper removal from carbon-saturated molten iron with FeS-based flux
Copper is one of the most harmful impurities in steel-making because of its role in causing metallurgical problems during thermo-mechanical processing,called heating embrittlement.To avoid adverse effects,the only op-tion for reducing the copper content in steel is through dilution.However,this method does not truly solve the problem and instead contaminates the pure molten iron.There are strict limits on its content in most steel grades.Once copper is introduced into steel-making process,it will cannot be oxidated from iron-based melt during the con-ventional refining process but can be sulfurized by sulfur-containing agents according to the strong affinity between S and Cu at high temperature.The decopperization in carbon saturated iron melt using different sulfur-containing a-gents was studied.The results are shown that when using Na2S-FeS slag with a ratio of xFes/xNa2s=6/4(x is mole fraction),95.1％of copper can be removed in 15 min.Increasing the ratio of Na2S in the slag can limit the increase of sulfur content in iron caused by mass transfer from slag.When xFeS/xNa2s=2/8,the sulfur mass fraction in iron after decopperzation can be controlled in 0.032％.Adding oxides such as A1203 to the sulfide slag can significantly limit sulfur transfer from the slag to iron,but it has a certain impact on the copper removal.
short process steel-makingscrap recycleresidual elementcopper removalsulfide flux
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