Study On Solid State Reduction And High Efficient Utilization Of V-Ti Magnetite Concentrate

Vanadium-titanium magnetite ore is quite rich in Pan-Xi zone of China and its explored reserve is up to 98.49 billion tons,which accounts for 95%of total vanadium-titanium magnetite resource in China.It's important to transform the resource advantage into economic advantage and promote national economic development through comprehensive utilization of rich vanadium-titanium magnetite ore in China.V-Ti magnetite concentrate and titanomagnetite concentrate are the main products in mineral separation of this resource.To develop the efficient utilization technology based on resource characteristics of V-Ti magnetite concentrate in china,Panzhihua V-Ti magnetite concentrate was taken as raw material to study the solid state reduction behavior and strengthening technology of reduction process by thermodynamic principle and modern analysis equipments such as X ray powder diffraction and optical microscope.On this basis,electric furnace smelting technology of pre-reduction pellet and grinding-magnetic separation technology of metallized pellet of V-Ti magnetite concentrate were studied in this paper.The following conclusions were obtained:The thermodynamic study on V-Ti magnetite concentrate carbothermal reduction showed that iron oxide reduction would not be the reaction limiting factor,and vanadium oxide was more difficult to be reduced than iron oxide,but less than titanium oxide.Complex compound formed from titanium oxide and CaO,MgO would increase the difficulty of further reduction of titainium oxide,the initial reaction temperature of perovskite reduction is over 2200K under the standard state.The study on solid reduction behavior of V-Ti magnetite concentrate showed that pre-oxdiation can accelerate the reaction rate and increase metallization rate of the reduction product,which increased with temperature rising and the passage of time.The mechanism is that pre-oxdiation made the new kinetics form in V-Ti magnetite concentrate,destroyed the structure of raw ore,and improved dynamics condition in reduction process.The additive and pre-oxidation treatment can farther destroy the minerals structure,and lots of mico-holes were appeared in the reduction products,which promoted the reduction of iron oxide significantly,and accelerate the reaction rate.The study on electric furnace smelting of V-Ti magnetite concentrate pre-reduction pellet showed that with appropriate reducing agent ratio, rational slag system,appropriate metallization rate of pre-reduction pelltes,electric furnace smelting temperature and time,the separation direction of vanadium and titanium would be controlled.The vast majority of vanadium would be collected in the pig iron and titanium richen in slag.Under the conditions of alkalinity R(CaO/SiO₂) 1.2,MgO content in slag 6%,Al₂O₃ content in slag 9%,appropriate metallization rate 70%,smelting temperature 1500℃,smelting time 10min,the pig iron was obtained with iron grade of 96.90%,iron recovery of 99.47%, vanadium content of 0.52%,vanadium recovery of 80.20%was produced,TiO₂ content of 66.13%in slag.The smelting slag had good fluidity and the smelting process was in smooth operation.The results of grinding separation of metalized pellet showed that the effective separation of iron,titianium and vanadium from V-Ti magnetite concentrate was realized.Proper process condition were as fallows, reduction temperature of 1050℃,reduction time of 100min,grinding fineness of -0.045mm accounting for 84.88%,magnetic separation intensity of 800Gs.At optimum conditions,the magnetic substance (direct reduced iron powder) with total Fe grade of 90.32%,and iron recovery rate of 95.20%was obtained;V₂O₅ content was 1.72%and TiO₂ content was 29.68%in the non-magnetic material(rich vanadium-titanium material).Electric furnace smelting flow of pre-reduction pellet solved problems such as great difficulty of V-Ti magnetite concentrate pre-reduction technology and the control of vanadium-titanium in furnace smelting process.The obtained pig iron containing vanadium can be used as the feeds of vanadium extraction and steelmaking,titanium slag was used to produce titanium dioxide by sulfuric acid method,from which, iron,vanadium and titanium of V-Ti magnetite concentrate were recovered. In addition,this process had following advantages of relatively simple process,mature technology,short flow,efficiency productivity,no solid and liquid waste,and less pollution.Compared to grinding separation flow of metallized pelltes,it has advantages that using electric furnace smelting flow of pre-reduction pelltes as treatment to Panzhihua V-Ti magnetite concentrate.