Basic Research On The Reduction And Carbonization Of Titanium-Bearing Blast Furnace Slag In CH₄-H₂ System At Low Temperature

China is rich in titanium resources,mainly based on low-grade vanadium-titanium magnetite resources,which is difficult to comprehensively utilize.The iron concentrate and titanium concentrate can be obtained from vanadium-titanium magnetite in Panzhihua area through beneficiation processes.The iron concentrate would be used in the blast furnace ironmaking process to produce vanadium-bearing molten iron and titanium-bearing blast furnace slag containing about 23%TiO₂,and the recycling of titanium resources in titanium-bearing blast furnace slag is a worldwide problem.Relevant scientific research workers in China have proposed many methods for the comprehensive utilization of titanium-bearing blast furnace slag.But currently only high-temperature carbonization-low-temperature selective chlorination process has application prospects due to various limitations.However,the high-temperature carbonization-low-temperature selective chlorination process still faces problems such as high carbonization energy consumption,incomplete carbonization,and difficulty in carbon addition,which limits its further promotion and application.Therefore,a low-temperature reduction and carbonization process of titanium-bearing blast furnace slag based on gas-solid reaction was proposed in this study to replace the high-temperature carbonization process,and relevant basic research was carried out.In this paper,the basic titanium-bearing phase titanium dioxide and perovskite-perovskite contained in the titanium-bearing blast furnace slag were used as research objects,the CH₄-H₂ gas mixture was used as reductant and carburizing agent.Basic research on the reduction and carbonization behavior ofTiO₂ and perovskite-magnesium was carried out by combining theoretical calculation with experimental research,and the feasibility of low-temperature reduction and carbonization of titanium-bearing blast furnace slag in CH₄-H₂ system was preliminary proved.The main conclusions of this paper are as follows:（1）Thermodynamic phase equilibrium analysis in theTiO₂-CH₄-H₂,CaTiO₃-CH₄-H₂,MgTiO₃-CH₄-H₂ and CaTiO₃-MgTiO₃-CH₄-H₂ systems was performed were performed by theoretical calculation.The results indicated thatTiO₂ and MgTiO₃ could be ultimately reduced and carbonized toTiC_xO_y by CH₄-H₂ gas mixture at temperature above 1200℃,while the temperature for reduction of CaTiO₃ was above 1300℃.In the CaTiO₃-MgTiO₃-CH₄-H₂ system,MgTiO₃ is reduced before CaTiO₃.（2）The reduction and carbonization behavior ofTiO₂ samples in CH₄–H₂ system were studied in a temperature range of 1200 ^oC to 1450 ^oC.Experimental results showed thatTiO₂ could be reduced completely toTiC_xO_y at 1350 ^oC and above after 8h reaction.It was also found that the reduction extent ofTiO₂ increased with increasing time and temperature at a low temperature range（below 1350 ^oC）.However,a much higher temperature（above 1350 ^oC）would hinder the further carbonization ofTi_xO_y for the production of deposited carbon.Additive Fe₂O₃ strongly facilitated the reduction reaction ofTiO₂,whileTiO₂ could be completely reduced and carbonized toTiC_xO_y at only 1200 ^oC.（3）The reduction and carbonization behavior of perovskite-geikielite samples in CH₄–H₂ system was studied in a temperature range of 1300 ^oC to 1450 ^oC.Experimental results showed that perovskite-geikielite sample could be reduced completely toTiC_xO_y at 1400 ^oC and above after 8h reduction,while geikielite was reduced prior to perovskite.The reduction and carbonization extent of samples increased with increasing time and temperature when in a low temperature range（below1400 ^oC）.However,a much higher temperature（above 1400 ^oC）would hinder further carbonization ofTiC_xO_y.Additive Fe₂O₃ strongly facilitated the reduction of perovskite-geikielite,while it also accelerated the production of deposited carbon.（4）The verified reduction and carbonization experiment of titanium-bearing blast furnace slag using CH₄–H₂ gas mixture was studied at 1200 ^oC.There was obviousTiC_xO_y formation in the reduced product,which preliminarily confirmed the feasibility of low-temperature carbonization of titanium-bearing blast furnace slag using CH₄-H₂gas mixture to prepareTiC_xO_y.