Physical Properties Of Molten Salt System For Carbothermal Chlorination Of High Calcium Magnesium Titanium Slag

Titanium tetrachloride(TiCl₄)is an important intermediate material for the preparation of titanium,titanium alloy or titanium dioxide.At present,the main methods of producing TiCl₄ in industry are boiling chlorination and molten salt chlorination.Compared with boiling chlorination method,molten salt chlorination method has the advantages of strong adaptability to raw materials,low chlorination temperature,and can treat high calcium and magnesium raw materials.It is the most suitable chlorination method for titanium industry in China.At present,in the process of producing titanium tetrachloride by molten salt chlorination,the composition of molten salt fluctuates in the furnace,resulting in a series of problems,such as bubbling of molten salt medium,"bubbling",a large number of waste molten salt and so on.This restricted the further development of molten salt chlorination technology to a certain extent.Therefore,it is of great significance and practical value to study the physicochemical properties of molten salt medium for low-grade high calcium magnesium titanium slag.In order to clarify the composition of molten salt medium,the thermodynamics of titanium slag chlorination process was studied:HSC was used to calculate and draw the relationship curve of?Gof titanium slag chlorination reaction with temperature in the range of molten salt chlorination temperature.The results showed that the direct chlorination of TiO₂ could not be spontaneous without carbon addition.Under the condition of adding carbon,each component in high calcium magnesium titanium slag can be chlorinated at molten salt chlorination temperature,and the chlorination order of each substance in high calcium magnesium titanium slag is Ca O>Mn O>Mg O>Fe₂O₃>Fe O>TiO₂>Al₂O₃>Si O₂.At the same time,the saturated vapor pressure of each chlorination product was analyzed,and the corresponding volatility order of chloride was SiCl₄>TiCl₄>AlCl₃>FeCl₃>FeCl₂>MnCl₂>MgCl₂>CaCl₂?The phase diagram was drawn by factpage,and the phase composition of molten salt for carbothermal chlorination of low-grade high calcium magnesium titanium slag was established.In view of the test problem caused by high solid content in molten salt medium,this paper creatively adopts vacuum melting stratification technology to separate molten salt medium from unreacted titanium slag and petroleum coke,studies the density,surface tension and viscosity of molten salt medium in industrial production,finds out the change rule of physical properties of molten salt system at 700?800?,and fills the gap for molten salt chlorination production The lack of physical property data of molten salt media has laid a solid foundation for scientific guidance of molten salt chlorination production and regulation of molten salt composition.The experimental study of NaCl-MgCl₂-CaCl₂ Ternary Molten salt system was carried out,and the physical properties of molten salt were measured under different temperature and composition.The effects of the components in the system of NaCl-MgCl₂-CaCl₂ ternary molten salt on the properties of physical chemistry were studied.The Density of molten salt system increases with the increase of MgCl₂ content,and the viscosity of molten salt system decreases at first and then increases.The density and viscosity of molten salt increase with the increase of CaCl₂ content.The test results of surface tension of molten salt system show that the surface tension of molten salt system can be reduced by adding MgCl₂ to NaCl-CaCl₂.At the same time,the control range of MgCl₂and CaCl₂ in molten salt chlorination process of high calcium magnesium titanium slag was established:The content of MgCl₂ in molten salt system should be controlled between 12.5%and 26.3%.The amount of CaCl₂ should be less than 10%.The results can be directly applied to the production of molten salt chlorination process.At the same time,the optimum molten salt system composed of NaCl-55%,MgCl₂-35%and CaCl₂-10%was obtained.