Coexistence Theory of Slag Structure and Its Application to Calculation of Oxidizing Capability of Slag Melts

The coexistence theory of slag structure and it's application to calculation of the oxidizing capabilities of slag melts is described. It is shown that the law of mass action can be widely applied to the calculation of oxidizing capabilities of slag melts in combination with the coexistence theory of slag structure.For slag melts containing basic oxides FeO and MnO, their oxidizing capabilities can be expressed by NFetO=NFeO+6NFe2O3, while for slag melts containing basic oxides CaO, MgO, etc., in addition to FeO and MnO, their oxidizing capabilities can be given as NFetO=NFeO+6NFe2O3+8NFe3O4.

Applicability of law of mass action to distribution of manganese between slag melts and liquid iron

According to the law of mass action and the coexistence theory of slag structure, the distribution of manganese between MnO FeO SiO 2 and MgO MnO FeO SiO 2 slag melts as well as liquid iron was analyzed. It is shown that K ′ Mn and K MnO are only dependent on temperature and don’t change with basicities and compositions of slag melts. So the distribution of manganese between the above mentioned slag melts and molten iron obeys the law of mass action. But analysis of experimental results from other sources shows that K ′ Mn and K MnO really change with basicities of slag, which is probably arisen from not approaching equilibrium under low basicity slag melts.

Applicability of mass action law to sulphur distribution between slag melts and liquid iron

According to the mass action law and the coexistence theory of slag structure, the calculating models of mass action concentration for CaO-MgO-FeO-Fe2O3-SiO2, CaO-MgO-MnO-FeO-Fe2O3-P2O5-SiO2 and CaO-MgO-MnO-FeO-Fe2O3-Al2O3-P2O5-SiO2 slag melts are formulated and sulphur distribution between the slag melts and liquid iron is treated. It is found that CaO, MnO and FeO promote desulphurization, while MgO is detrimental to desulphurization. In addition, the sulphur distribution coefficients between the slag melts and liquid iron are presented.

CaO-FeO-SiO_2渣系的作用浓度计算模型

根据炉渣结构的共存理论、CaO-SiO_2、CaO-FeO-SiO_2相图及有关的热力学数据,推导了1600℃下CaO-FeO-SiO_2渣系作用浓度的计算模型。用此模型计算得的等N_(FeO)曲线族与实测等~αFeO线甚为符合。等N_(FeO)线的顶点位于碱度B=1.703～1.778之间,因此,脱碳和沉淀脱氧时,应当尽可能保持此碱度,而扩散脱氧时则应避开此碱度。硅酸盐的等作用浓度曲线族与相应炉渣区间的等温线相似的事实说明硅酸盐是影响本渣系熔点的重要因素。

PbO—SiO_2渣系的作用浓度计算模型

按照炉渣结构的共存理论,PbO-SiO)2渣系相图和有关的热力学数据,推导了本渣系各组元的作用浓度计算模型.利用此模型计算的作用浓度 N_(PbO)与文献上实测的活度值 a_(PbO)符合甚好,由此证明共存理论对含有正方晶系 PbO 的有色金属渣系 PbO-SiO_2也是适用的。

CaO-SiO_(2)-MgO-Al_(2)O_(3)渣系渣铁间硫分配比热力学模型

为了探明高炉渣系组成对高炉渣脱硫能力的影响,根据分子-离子共存理论,建立了CaO-SiO_(2)-MgO-Al_(2)O_(3)高炉渣系与铁液间硫分配比的热力学模型,利用试验测定值对其进行验证与修正,探究碱度R、w((MgO))/w((Al_(2)O_(3)))和w((Al_(2)O_(3)))对炉渣脱硫能力的影响。研究结果表明,修正后的CaO-SiO_(2)-MgO-Al_(2)O_(3)高炉渣系硫分配比(LS)热力学模型能较好地预测熔渣的脱硫能力,修正后的相对误差为8%,较修正前的相对误差降低了11%;当w((MgO))/w((Al_(2)O_(3)))=0.25~0.45,w((Al_(2)O_(3)))=15%时,随着碱度R的增加,炉渣的脱硫能力(LS)增大;当w((Al_(2)O_(3)))=15%,R=1.15~1.25时,随着w((MgO))/w((Al_(2)O_(3)))的增加,炉渣的脱硫能力(LS)增大;当w((MgO))/w((Al_(2)O_(3)))=0.25~0.45,R=1.20时,随着w((Al_(2)O_(3)))的增加,炉渣的脱硫能力(LS)减小,故高Al_(2)O_(3)条件下应适当增加炉渣中的w((MgO))/w((Al_(2)O_(3)))。