Process In Extracting Vanadium From Pangang Vanadium Titanium Magnetite Blast Furnace Slag

Vanadium has excellent physical and chemical properties,known as"modern industrial monosodium glutamate"and"metal vitamins".It is widely used in the fields of steel,aeronautics and astronautics,battery,chemistry and chemical,glass,optics and medicine.98%of the world's proven vanadium reserves exist in vanadium titanium magnetite,while Panzhihua's vanadium reserves account for more than half of China's.The iron and part of vanadium was extracted from the vanadium titanium magnetite in industrial production,a large number of V-bearing blast furnace slag are difficult to recycle and have been piled up,which is not only pollute the environment but also waste the V-resources.At present,the main way of vanadium extraction in blast furnace slag is sulfuric acid leaching,which is a high-cost process.Also a large amount of calcium salt in the slag reacts with the sulfuric acid to form CaSO₄ coating on the surface,which resulting the leaching efficiency reduced.Therefore,exploring new low-cost and efficient blast furnace slag extracting vanadium process will have great significance in economy and environment.The formation process,mineralogical characteristics,morphologies,chemical compositions and phase compositions of the air-cooled blast furnace slags were investigated by SEM,EDS,XRF and XRD.The three-step process route of oxidation roasting,acid leaching and ammonia precipitating is adopted to deal with the air-cooled blast furnace slag.The various factors affecting the leaching rate of vanadium were investigated in the process of roasting and leaching,the vanadium precipitation process was determined by analysis the chemical composition with ICP-OES.The surface of the blast furnace slag was covered with yellow dense foamy solid with a metallic luster,and has some pores and holes.There was a compact layer of dark gray between the outer surface and inside,the surface of this layer is smooth and almost without holes.In the SEM images,there were lots of spherical particles uniform distribute on the surface of this layer.The inside of slag was dark gray porous loose structure,the surface is rough,and the silvery white iron beads were embedded in it.The main chemical components and contents of slag were calcium oxide?26.22%?,silicon dioxide?24.03%?,titanium dioxide?18.81%?,aluminum oxide?12.48%?,magnesium oxide?8.01%?,iron oxide?3.66%?,vanadium pentoxide?0.69%?and sulfur dioxide?3.20%?.And the main mineral components of slag were pertovskite,titanium diopside,magnesia-alumina spinel,titanium rich diopside,etc.Vanadium mainly existed in magnesia-alumina spinel in the form of oxides.The vanadium extracting technology from vanadium-titanium-magnetite blast furnace slag was studied detailed using single-factor conditional experiment.The various factors affecting the leaching rate of vanadium were investigated in the process of roasting and leaching.The best roasting technology conditions were:mineral size:200 meshes;roasting temperature:600?;roasting time:2 hours.The best extracting technology conditions were:leaching solvent:27%HCl;solid-liquid ratio:1:4;leaching temperature:90?;leaching time:3 hours.After being treated by the best roasting technology and extraction technology in above,the extracting rate of vanadium can reach up to 85.96%.The Fe and Ti precipitation pH was close to V precipitation pH value in the leaching solution,so we used TBP to remove Fe from leaching solution,and then remove Ti from the Fe-removed solution.Finally,we used ammonia to adjusting the pH of Fe-Ti-removed solution and obtained the white precipitate.Roasted the white precipitate in muffle oven at 500?for 3 hours,and the purity of vanadium product was nearly 94.86%?V₂O₅?.