Experimental Study On The Liquidus Temperature Of CaO-SiO₂-10%Al₂O₃-5%MgO-TiO₂ System

It is the most fundamental,effective and non-substitutable way to study the development of the metallurgical slags based on the thermodynamic data in multi-components phase diagrams,in which the liquidus temperatures are the most important thermodynamic information.However,the liquidus temperatures are not completely investigated for the Ti-bearing slags,which seriously restricts the development and comprehensive ulitization of the Ti-bearing slags.The research on liquidus temperatures from this paper not only can obtain abundant thermodynamic information for the optimization and application of the phase diagrams,but also can provide a reference for the effective determination of the liquidus temperatures in metallurgical slag systems.In the present reaserch,the melting temperatures were determined by the single thermal couple method for different w(CaO)/w(SiO2)and w(TiO2)in the CaO-SiO2-10%Al2O3-5%MgO-TiO2 system,and the relationship of temperature with w(CaO)/w(SiO2)and w(TiO2)was discussed with the activities calculated by the molecule ion co-existence theory.The liquidus temperatures were then calculated by the thermodynamic equations for the specific area of the CaO-SiO2-10%Al2O3-5%MgO-TiO2 system.Based on the experimental results,the following conclutions could be obtained:(1)The melting temperature increased with the increase of w(CaO)/w(SiO2)at constant w(TiO2).The action concentration of low melting temperature substance of CaO·SiO2 was decreased with the increase of w(CaO)/w(SiO2),while the action concentration of the high melting temperature substance of 2CaO·SiO2 and 3CaO·MgO·2SiO2 increased.(2)The melting temperature increased with the increase of w(TiO2)at constant w(CaO)/w(SiO2).The action concentration of low melting temperature substance of CaO·SiO2 was decreased with the increase of w(TiO2),while the action concentration of the high melting temperature substance of CaO·TiO2 increased.(3)The relationship of melting temperature Twith w(CaO)/w(SiO2)and w(TiO2)could be expressed as x = exp(T/A+B)based on the thermodynamic principles,in which x stand for w(CaO)/w(SiO2)and w(TiO2),A and B are constant.(4)The liquidus temperatures of CaO-SiO2-10%Al2O3-5%MgO-TiO2 system in specific region were plotted based on the calculated result from the thermodynamic equations.The good agreement of the liquidus temperature with the article data indicated that the method adoped in the present reaserch was inabled to construct the correct liquidus temperature.