Slag Performance And Slag System Optimization Of Vanadium Titanomagnetite Slag In South Africa

Vanadium and titanium magnetite resources are widely distributed and are an important mineral raw material for the production of vanadium and titanium,which has a very high mining and comprehensive utilization value.However,in the process of extracting vanadium and titanium resources,due to the high content of titanium dioxide in the slag,the slag viscosity is too large,the slag iron separation is difficult,and the comprehensive utilization is difficult.With the rapid development of domestic iron and steel enterprises,iron and steel enterprises have an increasing demand for vanadium titanomagnetite.Countries improve the melting point and viscosity of slag from the perspective of optimizing smelting process,promote the separation of slag and iron in the melting process,reduce production costs and maximize economic benefits.The test raw material used in this study is South African vanadium titanium magnetite provided by Shaanxi Zhongxing Hengtai Investment Holding Co.,Ltd.,in which the content of V₂O₅in the raw material is as high as 1.98%and the content of TiO₂ is 13.13%,which belongs to"high vanadium and high titanium"vanadium titanium magnetite.The standard Gibbs free energy of each chemical reaction is calculated by Factsage software to determine the corresponding process parameter range in the smelting process of vanadium titanium magnetite.Test using single factor analysis of the melting temperature,alkalinity,carbon and magnesium oxide content in the four kinds of factors affect the performance of vanadium titanium magnetite metallurgical slag,and the melting slag series features and relationship of viscosity and the slag phase,get the best slag smelting process parameters.The following conclusions are drawn from the study:（1）According to the raw material properties of vanadium titanium magnetite in South Africa,the slagging process of vanadium titanium magnetite in South Africa is thermodynamically analyzed.The results show that the main substances affecting the viscosity of slag system are titanium carbide,titanium nitride and titanium carbonitride solid solution.The Gibbs free energy of each reaction is calculated by factage software.It is found that with the gradual increase of temperature,iron oxide is reduced to elemental iron at 996K.Vanadium oxide is first reduced to VC in the melting process,and then V₂C and VO are generated with the increase of temperature.When the temperature is 1737K,it will be reduced to V.When the temperature is 1469K,titanium oxide is first reduced to titanium nitride,and when the temperature rises to 1567K,it is reduced to titanium carbide,and the higher the temperature,the greater the amount of titanium carbonitride.（2）Vanadium titanomagnetite slag is obtained under different experimental conditions.By measuring the melting temperature of vanadium titanomagnetite slag,it is obtained that with the increase of melting temperature,the softening temperature,hemispherical temperature and flow temperature of slag all show a trend of increasing first and then decreasing.When the melting temperature is 1450℃,the softening temperature,hemispherical temperature and flow temperature of slag system reach the minimum values,which are 1236℃,1238℃and 1243℃respectively.With the continuous increase of basicity,the corresponding softening temperature,hemispherical temperature and flow temperature of slag also gradually increased.With the increase of carbon allocation,the softening temperature,hemispheric temperature and flowing temperature of slag decrease first and then increase,in which when the carbon allocation is 5%,the flowing temperature of slag system obtains the minimum value of 1254℃.With the continuous increase of Mg O content,the hemispheric temperature and softening temperature of the slag both showed a downward trend,and the flow temperature first decreased and then increased slowly.When the Mg O content was 2%,the minimum flow temperature was 1234℃.（3）The slag of vanadium titanium magnetite was obtained under different experimental conditions.After analyzing the viscosity and phase composition of vanadium titanium magnetite slag,it was concluded that:With the increase of melting temperature,the initial viscosity of slag increases as a whole.The diffraction peak intensity of low melting point material decreases gradually,while that of high melting point material increases.When the melting temperature is 1450℃,the lowest viscosity of slag system is 0.130Pa·s.With the increase of basicity,the viscosity value of slag decreases first and then increases.When the basicity of slag system is 1.2,the viscosity value of slag reaches the minimum value.With the increase of carbon content,the viscosity of slag decreases first and then increases.When the carbon content is 5%,the viscosity of slag system gets the minimum value.With the increase of magnesium oxide content,the viscosity of slag decreases first and then increases,and the diffraction peak intensity of pyroxene and plagiarite in slag decreases from strong to weak.When the magnesium oxide content in slag is 10%,the viscosity value of slag system is 0.105Pa·s.（4）Through the comparative analysis of single-factor experimental results,the best theoretical melting ratio was obtained as follows:melting temperature of 1450℃,alkalinity of 1.2,carbon content of 5%,and magnesium oxide content of 10%.The softening temperature of the slag system under this optimal ratio is 1215℃,the hemisphere temperature is 1225℃,the flow temperature is 1234℃,the viscosity is 0.105Pa·s,the flowability of the slag system is good.