Kinetics Of Acid Vanadium-titanium Slag Reduction And Vanadium Extraction From Hot Metal With High Silicon

Smelting reduction with iron bath can explore a new way for refining vanadium-titanium magnetite because of its good condition for mass transfer, fast reaction rate and short refining time. And furthermore, high-grade vanadium slag obtained from oxidation of V-bearing hot metal can realize the efficient utilization of vanadium resource.The reduction of vanadium oxide and titanium oxide between carbon saturated molten iron and CaO-FeO-SiO2-TiO2-Al2O3-MgO-V2O5 slag was studied experimentally; and one kinetic model to describe the reducing process of vanadium and titanium was established according to the double-film theory. When the temperature is 1580℃, iron-slag ratio is 1:4, original V2O5 content is 1.9%, original TiO2 content is 45%, the reduction rate equations for vanadium oxide and titanium oxide are-d(%V2O3)/dt=4.91×10-4(%V2O3)-4.99×10-5,-d(%TiO2)/dt=6.84×10-5(%TiO2)-2.90×10-3 respectively. Both of the reactions are the apparent first class, and the limiting steps are the diffusion of vanadium and titanium in slag. The appearance activation for these two reactions is 370.94kJ/mol and 193.76kJ/mol respectively before the vanadium reduction reaches equilibrium. The calculated values basically agree with the experiment values, therefore the mathematical model can reveal the real experiment rule.Base on the kinetics model, the influences of some factors including temperature, iron-slag ratio and reacting time on the reduction of V and Ti were investigated. The results show that the reduction of V is quickly than Ti. At 1580℃the reaction of V reduction can reach the balance while Ti could not. High temperature and small iron-slag ratio are both beneficial to the reduction of V and Ti, so for the comprehensive consideration the optional conditions for the reduction are as presented follows:temperature 1540-1580℃, reaction time 60-80min, ratio of iron and slag 1:4. It also shows that high original V2O5 content and low original TiO2 content can make the V reducing reaction fast.As well as the oxidation kinetics of high silicon hot metal containing vanadium oxidized by ferric oxide was studied. The influences of some factors including temperature, initial content of silicon and vanadium in hot metal on oxidation of vanadium were investigated. The results show that the oxidation of vanadium reaches equilibrium in 20-25min and the oxidation rate is 88%. It also indicates the increasing initial content of vanadium and additive of Fe2O3 can promote the oxidation of vanadium. However, the increasing silicon in hot metal will restrain the oxidation of vanadium. High temperature will be helpful to the oxidation of vanadium while it will induce the gegenreaction of vanadium if the temperature is higher than carbon-vanadium converting temperature. Therefore, with the comprehensive consideration, the temperature should be controlled in the range of 1350℃and 1400℃. The results show that the oxidation of vanadium is an apparent first-order reaction and the apparent activation energy is 122.47kJ/mol which indicates that the diffusion of vanadium oxide in slag is the restrictive step of the oxidation.