含氧化镧精炼渣的热力学分析及性能优化

Thermodynamic analysis and performance optimization of refining slag containing lanthanum oxide

针对含La稀土钢精炼渣的优化问题,采用分子-离子共存理论计算碱度、钙铝比(C/A)、MgO含量、MnO含量、FeO含量以及La_(2)O_(3)含量对La_(2)O_(3)活度、传氧量及硫容量的影响,并采用正交试验法确定最合适的精炼渣配比,从矿相结构、熔点等方面分析优化后的精炼渣性能。研究得出,随着碱度、C/A、MnO含量、La_(2)O_(3)含量的增加,La_(2)O_(3)活度增加;随着FeO含量的增加,La_(2)O_(3)活度减小;MgO含量对La_(2)O_(3)活度影响不大。FeO和MgO的含量对传氧量的影响较大,两者会明显增加传氧量,而碱度、C/A以及La_(2)O_(3)含量的增加则会降低传氧量。碱度以及C/A的增大会增加熔渣硫容量,MnO、MgO、FeO的增加则会降低硫容量。当熔渣碱度为8、C/A=1.8、w(FeO)=0.4%、w(La_(2)O_(3))=12%、w(MgO)=3%、w(MnO)=0.6%时,La_(2)O_(3)的活度为0.003 1,传氧量为2.83×10^(-6),硫容量为0.635 4,此时La_(2)O_(3)活度和硫容量相对较大,传氧量相对较小,为最优配比。优化后熔渣的矿相主要以3CaO·Al_(2)O_(3)、2CaO·SiO_(2)、MgO以及含La_(2)O_(3)矿相为主,熔化温度为1 338℃,因此在冶炼温度下能够很好地化渣,满足精炼要求,为稀土钢冶炼技术提供理论基础。

Aiming at optimization for refining slag of rare earth steel containing La,effects of basicity,C/A ratio,MgO content,MnO content,FeO content and La_(2)O_(3) content on La_(2)O_(3) activity,oxygen transfer capacity and sulfur capacity were calculated by molecular-ion coexistence theory.The most suitable refining slag ratio was determined by orthogonal experiment method,and the performance of optimized refining slag was analyzed from the aspects of mineral phase structure and melting point.The results show that the activity of La_(2)O_(3) increases with the increase of basicity,C/A,MnO content and La_(2)O_(3) content.With the increase of FeO content,the activity of La_(2)O_(3) decreases,while MgO content has little effect on the activity of La_(2)O_(3).The content of FeO and MgO has a great influence on the oxygen transfer capacity,which will significantly increase the oxygen transfer capacity,while the increase of basicity,C/A and La_(2)O_(3) content will reduce the oxygen transfer capacity.The increase of basicity and C/A will increase the sulfur capacity of slag,while the increase of MnO,MgO and FeO will reduce the sulfur capacity.When the slag basicity is 8,C/A=1.8,w(FeO)=0.4%,w(La_(2)O_(3))=12%,w(MgO)=3%,w(MnO)=0.6%,the activity of La_(2)O_(3) is 0.0031,the oxygen transfer capacity is 2.83×10^(-6),and the sulfur capacity is 0.6354.The activity and sulfur capacity of La_(2)O_(3) are relatively large,and the oxygen transfer capacity is relatively small,which is the optimal ratio of refining slag.The mineral phases of the optimized slag are mainly 3CaO·Al_(2)O_(3),2CaO·SiO_(2),MgO and La_(2)O_(3),and the melting temperature is 1338℃.Therefore,the slag can be well melted at the smelting temperature and meet the refining requirements,which provides the theoretical basis for rare earth steel smelting technology.