Thermodynamic Stuby on the Removal of Copper in Steel Scrap by Sulfide Fluxes

废钢中的铜、锡、锑等杂质是传统炼钢工艺无法去除的。因此，必须开发经济的方法来去除这些杂质，以回收废钢。本文研究了硫化物助熔剂去除铁液中不稳定元素（主要是铜）的热力学。本研究包括以下四个部分。1)测量了Fe-S-C三元熔体基本体系的相平衡，并应用间隙溶液模型评价了该体系的热力学性质。2) Cu、Sn、Sb在Fe-S-C_<sat - bb_0中的活度。熔体通过实验确定。3) Cu、Sn、Sb、Ni、Cr、Mn、Mo在FeS-Na_2S通量和Fe-C_<sat>之间的分布比例。熔体在1673K时测量。Na_2S的加入增加了Cu的分布比L_<Cu>=（质量%Cu）_<通量>/[质量%Cu]_<铁>，从X_<NaS_<0.5>>=0时的9到X_<NaS_<0.5>>= 0.4时的最大值L_<Cu>=24。Na_2S还能显著降低铁液中的硫含量。评价了通量中CuS_<0.5>的活度系数，探讨了Na_2S对L_<Cu>的影响。结果表明，Na_2S降低了γ CuS_<0.5>，使L_<Cu>升高，但硫电位明显降低。Sn、Sb、Ni、Cr和Mo的分布比例很低，而L_<Mn>的分布比例很高。4)研究了碱性或碱土金属硫化物对L_<Cu>的影响。与Na_2S、Li_2S、K_2S的作用类似，SrS和BaS提高了铁液中的L_<Cu>，降低了铁液中的硫含量。各通量中L_<Cu>的最大值约为20 ~ 30。从热力学角度探讨了硫化剂对铁液中铜的脱除极限。本文的研究结果表明，利用硫化物助熔剂可以去除铁液中的铜。但L_<Cu>不足以满足实际应用。因此，开发有效的废钢重熔除铜工艺仍需进一步努力。少

The tramp elements such as Cu, Sn, Sb etc. in steel scrap can not be removed by the traditional steelmaking process. Therefore, economical prcesses to remove these impurities have to be developed for the recycling of steel scrap. Present work dealt with the thermodmynamics on the removal of tramp elements, mainly Cu, in liquid iron by using sulfide flux. The present investigation consisted of following four parts.1) Phase equilibria in the basic system of Fe-S-C ternary melt were measured and thermodynamic properties of this system were evaluated by applying interstitial solution model.2) The activities of Cu, Sn, Sb in Fe-S-C_<sat>. Melts were experimentally determined.3) The distribution ratio of Cu, Sn, Sb Ni, Cr, Mn or Mo between FeS-Na_2S flux and Fe-C_<sat>. melt was measured at 1673K. The addition of Na_2S to FeS increased the distribution ratio of Cu, L_<Cu>=(mass%Cu)_<flux>/[mass%Cu]_<iron>, from 9 at X_<NaS_<0.5>>=0 to the maximum of L_<Cu>=24 at X_<Nas_<0.5>>=0.4. Na_2S also … More considerably lowered sulfur content in liquid iron. The activity coefficient of CuS_<0.5> in flux was evaluated to discuss the effect of Na_2S on L_<Cu>. It was founs that Na_2S decreased gamma CuS_<0.5>, so that L_<Cu> increased in spite of the significant decrease of sulfur potential. The distribution ratios of Sn, Sb, Ni, Cr and Mo were very low, while L_<Mn> was very high.4) Effect of alkaline or alkaline earth metal sulfides on L_<Cu> was studied. Similar to the effect of Na_2S, Li_2S, K_2S, SrS or BaS increased L_<Cu> and lowered sulfur content in liquid iron. The maximum of L_<Cu> in each flux were about 20 to 30. Thermodynamic consideration was made to discuss the removal limit of Cu from liquid iron by sulfide fluxes.It was concluded from the present work that Cu can be removed from liquid iron by sulfide flux. However, L_<Cu> was not high enough for the practical application. Therefore, we need more effort to develop the effective Cu removal process from remelted steel scrap. Less