Preparation Of Titanium And Impurities By Molten Salt Electrolysis Of Titanium-containing Waste Residues

When Kroll metode produces one ton of sponge titanium,it would produce200kg titanium-containing waste residue,which TiO₂ content was between 40%to88%.Due to the fine granularity and compact structure of the titanium-containing waste slag,the smelting temperature of the electric furnace needs to be increased when titanium-containing waste residue was returned to the electric furnace.And Titanium-containing waste residue could cause clogging,when the amount of titanium-containing waste residue exceeded 15%.The low utilization rate of titanium-containing waste slag leaded to the waste of titanium resources.The use of nickel foam wrapped around the cathode to increase the three-phase inter-face source,which was conducive to improving the electrochemical activity of the cathode,accelerated the rate of deoxygenation,and was conducive to the removal of impurities.As the forming pressure increases,the porosity of the cathode sheet decreased,and the particle size decreased.As the sintering temperature increases,the porosity of the cathode sheet decreased and the particle size increased.With the increase of carbon powder doping,the cathode porosity increased linearly.When the molding pressure was 4 MPa and the sintering temperature was 1050°C,the porosity of cathode was 35.12%.At this time,the cathode has the best electrochemical activity,and the electrolytic product had a titanium content of 96.92%and an oxygen content of 1.82%when the nickel cathode coated with nickel foam was electrolyzed at 900°C for 12 h.The effect of carbon powder doping on the electrode deoxidation was not significant.When the molding pressure was 4 MPa and the sintering temperature was1050°C,nickel foam coated cathode had better electrochemical activity.Electrolysis temperature and electrolysis voltage had a great influence on electrolysis in electrolysis parameters.With the increase of the electrolysis temperature,the electro-deoxidation efficiency increased.When electrolytic temperature was too high,the anode carbon rod carbon powder falled off,which occured micro-short circuit during electrolysis,and the rate of electro-deoxidation decreased.The titanium content was 89.80%at 900°C electrolysis9 h,then the electrolysis temperature was better.If the electrolysis voltage was too low,the decomposition voltage of titanium metal can not be obtained.When the electrolysis voltage is higher than 2.6 V,metallic titanium could be obtained by electrolysis.During electrolysis,Ca removed from the ultrafine titanium slag was dissolved in the molten salt.Impurities such as Mn,Fe,Al,and Si are reduced to the corresponding element,which entered the molten salt.A small amount of Fe,Si,Al produced FeCl₃,SiCl₄,and AlCl₃ low-boiling compounds volatilized to remove.A small amount of Fe,Si and Al remained in the cathode with Ti formed TiFeSi₂ alloy and TiAl₃ alloy.With the prolongation of electrolysis time and the increase of electrolysis voltage,electrolytic products of CaTiO₃,Ti₂O₃,TiO and Ti occurred sucessively.The process of electro-deoxidation is CaTiO₃?Ti₂O₃?TiO?Ti.Electro-deoxidation was mainly controlled by the ionization of O and the diffusion of O atoms in the cathode oxide.