Study On The Process And Mechanism Of Composite Roasting Additive For Strengthening Direct Vanadium Extraction From Vanadium-titanium Magnetite

Vanadium in vanadium-titanium magnetite?V[III]?mainly replaces iron?Fe[III]?in the magnetite phase in the form of isomorphism,while the magnetite lattice is stable and needs to be under high temperature and oxidizing atmosphere,the structure can be fully destroyed and vanadium can be released.Generally,a high-temperature oxidative roasting method can be employed to destroy the magnetite crystal structure.In order to enhance the effect of the roasting process,a roasting additive can be added during the roasting process.In this paper,the vanadium-titanium magnetite concentrate in western Liaoning is taken as the research object.The vanadium-titanium magnetite direct vanadium extraction process is adopted,and a high-efficiency composite roasting additive is selected,which significantly improves the vanadium leaching rate and determines the suitable Vanadium extraction process parameters.At the same time,the mechanism of the enhanced calcination of vanadium by the composite roasting additive is revealed.The main conclusions drawn are as follows:Compared with the vanadium extraction effect of various roasting additives,it is known that the K₂SO₄/KCl composite roasting additive has the most significant effect.In K2SO4/KCl dosage 7 wt%,ratio 6:4,calcination temperature 950°C,calcination time1 h,leaching temperature 95°C,leaching time 1.5 hours,sulfuric acid concentration 10%?v/v?,liquid-solid ratio 3 ml/gram The vanadium leaching rate can reach 82.04%,which is 36.24%higher than that of the blank roasting under the same conditions.Crystallographic analysis showed that the vanadium-bearing magnetite roasting vanadium is the process of transforming vanadium-bearing magnetite into hematite.During this process,the crystal undergoes a reconstituted transformation,and vanadium is dissociated through XRD,SEM-EDS and other detection methods for the phase transition in the roasting-leaching process and the migration and transformation of vanadium,the main mechanism of action of the composite roasting additive to enhance vanadium extraction is as follows:in the roasting process,the magnetite is fully destroyed.The structure of vanadium-bearing minerals promotes the formation of potassium vanadate and inhibits the formation of calcium vanadate,which is beneficial to the extraction of vanadium.In the process of leaching,due to the suppression of the formation of the acid-consuming substance calcium vanadate,the dissolution of vanadium-containing vermiculite is promoted,which is conducive to the dissolution of vanadium.The kinetic analysis of the acid leaching process using the classical nuclear shrinkage model shows that the apparent activation energy of the leaching process after K2SO4/KCl calcination is reduced from 35.22 kJ/mol of blank calcination to 25.33kJ/mol,and the reaction grade of sulfuric acid concentration.The number is reduced from 0.8180 for blank calcination to 0.5405.Compared with blank calcination,the roasting of composite additives can increase the mineral activity,accelerate the leaching process,and reduce the dependence of the reaction on high temperature and high acid.