Formation And Mechanism Of Magnesium Titanate In The Process Of Avnadium-titanium Magnetite Direct Reduction

At present,the titanium is difficult to be utilized using blast furnace smelting or other comprehensive utilization processes of vanadium titanomagnetitc ore.Thus,a new process for recovering both iron and titanium resources was proposed in this study.The magnesium compound as additive was added to the reduction process of vanadium titanomagnetite ore,transforming Ti into magnesium titanate and Fe into metallic iron,then these two products can be obtained by magnetic separation.Effects of Mg-Ti ratio,temperature,types of reductant,roasting time and types of magnesium compound on the formation of magnesium titanate were investigated in carbonthermic reduction of the Chende Vanadium titanomagnetite concentrates(the main phases are magnetite and ilmenite).The results showed that the process of preparation of magnesium orthotitanate from vanadium-titanomagnetite ore by direct reduction is feasible,and pure Mg2TiO4 particles were formed-a-in the conditions of MgO as additive,Mg-Ti ratio of 3,temperature of 1250℃,coke dosage of 100%and roasting time of 180min,furthermore metallic iron product with Fe grade of 92.54%,Fe recovery of 94.67%was obtained by magnetic separation.The reduction behavior of vanadium titanomagnetite in the presence of MgO was researched by thermodynamic and gaseous product content analysis.The results showed that MgO would not affect the reduction process of magnetite,but form magnesium titanate by the reaction with ilmenite which can promote the reduction of ilmenite.This is because the reaction of MgO and ilmenite to magnesium titanate and Fe more easily occurs than the reduction of ilmenite without MgO,Mg2TiO4 was formed instead of FeTi2O5 in the presence of MgO,the formation of Mg2TiO4 was beneficial to the reduction of FeTiO3 as well as the separation of Fe and Ti.In order to reveal the formation mechanism and rules of magnesium titanate,the roasting products of pure ilmenite and MgO under different conditions were investigated.The results showed that the reducing atmosphere is necessary to preparation of magnesium titanate,although Mg can replace Fe and form magnesium titanate without reductant,the generated magnesium titanate contained a lot of Fe.The content of Fe in magnesium titanate was reduced and pure magnesium titanate generated when adding reductant.The reducibility of ilmenite was main factor for the purity of magnesium titanate,the effective of the reduction improved and the the content of Fe in magnesium titanate reduced with the increasement of temperature and the prolongation of roasting time.With the increasing of MgO dosage,the magnesium titanate phase transformed along MgTi2O5→MgTiO3→Mg2TiO4 path at the temperature of 1250 ℃;and with the increasing of temperature,the magnesium titanate phase transformed along MgTiO3--Mg2TiO4 at the Mg-Ti ratio of 2.