| Vanadium-titanium magnetite is a characteristic metal resource rich in valuable elements such as iron,vanadium,titanium,and cobalt,chromium,and nickel,and has extremely high economic value.At present,the treatment of vanadium-titanium magnetite is mainly divided into blast furnace method and non-blast furnace method.The blast furnace method,as a mature method,occupies an important position in the treatment of vanadium-titanium magnetite,but has the disadvantages of low comprehensive utilization of resources,large environmental pollution,and high energy consumption.Non-blast furnace smelting technology is not yet fully mature and needs to be further improved.In view of the problems existing in the existing technology for processing vanadium-titanium magnetite,the development of an efficient and green method for processing vanadium-titanium magnetite is still an inevitable choice for the efficient utilization of vanadium-titanium magnetite.Therefore,this paper proposed a new idea based on acid-base double-cycle oxygen-rich impurity removal pretreatment-hydrochloric acid leaching to refine titanium and recover iron..The leaching behavior of each element of vanadium-titanium magnetite in solution was analyzed systematically.After research,the following conclusions were reached:(1)X-ray diffraction,scanning electron microscopy,and energy spectroscopy were used to analyze the process mineralogy of vanadium titanomagnetite,and it was concluded that the raw ore mainly contains silicon oxide,ilmenite,titanomagnetite,and calcium silicate minerals;aluminum,Magnesium and other elements are enriched in a small amount and are composite minerals with iron,oxygen,and titanium;vanadium is diffusely distributed,and is mainly combined with ilmenite minerals and calcium silicate minerals.(2)The results of thermodynamic calculations show that:in an alkali leaching solution at a temperature of 448?573 K and an oxygen partial pressure of 2 MPa,an increase in temperature is favorable for the formation of titanate and the reaction of vanadium,silicon,aluminum and other elements with sodium hydroxide to generate corresponding sodium The salt is transferred to the liquid phase.In a hydrochloric acid solution at a temperature of 348?448 K,the Gibbs free energy of the reaction of sodium titanate with hydrochloric acid is negative,and the more negative the Gibbs free energy of the reaction with the temperature rise,the more favorable the titanium dioxide formation.Iron,magnesium,and calcium can react with hydrochloric acid to enter the liquid phase.Increasing the temperature is beneficial to the separation of iron and impurity elements from titanium dioxide.In an alkali leaching solution at a temperature of 313?353 K,the Gibbs free energy of ammonium metavanadate that is complexed with ammonia and sodium vanadate becomes negative,however,increasing temperature can inhibit the formation of ammonium metavanadate.(3)Study on the oxygen-rich alkaline leaching process of vanadium-titanium magnetite,the effects of the reaction time,liquid-solid ratio,oxygen partial pressure,particle size of vanadium-titanium magnetite,sodium hydroxide mass fraction,and reaction temperature on the leaching rates of vanadium and impurities silicon and aluminum Impact.The results showed that the decomposition conditions were a reaction time of 2 h,a liquid-solid ratio of 15:1,an oxygen partial pressure of 2 MPa,a particle size of vanadium titanomagnetite of 40?48?m,a mass fraction of sodium hydroxide of 30%,and a reaction temperature of 260?The leaching rate of vanadium is 60.65%,and the removal rates of silicon and aluminum are 70.22%and 77.86%,respectively.The appearance and appearance of vanadium-titanium magnetite after oxygen-rich alkali leaching changed from the original dense and hard ore phase to a loose lamellar structure.Ilmenite reacted with sodium hydroxide to generate ilmenite,silicon and other elements combined with minerals.The sodium hydroxide reacts to form the corresponding sodium salt,and the calcium silicate does not react with the alkali and is concentrated in the slag.(4)The effects of hydrochloric acid mass fraction,leaching temperature,and leaching time on the TiO2 conversion rate and Fe2O3 leaching rate were investigated in the alkaline leaching pretreatment slag-hydrochloric acid leaching process.The results showed that the hydrochloric acid mass fraction was 22%,the leaching temperature was 120?,When the leaching time is 1.5 h,the content of TiO2,SiO2 and Fe2O3 in the titanium-rich material obtained by acid leaching are 87.00%,10.10%,and 0.57%,respectively.The conversion rate of TiO2 and the leaching rate of Fe2O3 are 90.00%and 99.88%,respectively.The results of XRD analysis in the titanium-rich material showed obvious rutile TiO2.The calcium silicate in the raw ore did not react with the alkali,was decomposed by hydrochloric acid during acid leaching,Ca was removed,and Si did not react with hydrochloric acid and entered the solid phase as impurities(5)The effects of ammonia mass concentration,complexation temperature,and solution pH on the complexation reaction of ammonium metavanadate were investigated in the process of vanadium precipitation with ammonia leaching in alkaline leaching solution.The results show that the maximum vanadium precipitation rate is 85.60%when the ammonia water mass fraction is 3%,the complexing temperature is 60?,and the solution pH is 9. |
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