| Vanadium-titanium magnetite is a kind of rich resource in China, and now it is mainly used in blast furnace smelting process, it is difficult to achieve its comprehensive utilization. In this paper, the solid-phase reduction behavior and magnetic separation process intensification of vanadium titanomagnetite concentrate from Chengde was systemically studied by thermodynamic principles, chemical analysis, phase analysis and SEM analysis.On this basis, the process parameters for the comprehensive utilization of vanadium-titanium magnetite with new technology are optimized and also provide a theoretical basis. The conclusions show as following:(1) By studying the influence of C/O, reduction temperature, reduction time and forming pressure on the metallization of reduction products, the optimum parameters of the experiment are obtained as follows:forming pressure is50MPa, C/O is1.2, the reduction temperature is1350℃, reduction time is60min. Under the conditions, the metallization rate of reduction product reached91.04%.(2) Hot pressing and microwave heating can strengthen the vanadium-titanium magnetite reduction process, and with the temperature increased,the effect is more significant, the metallization rate of reduction product were90.53%and91.91%at1350℃. In addition, the use of microwave heating can make samples restored dense structure and fewer stomata. At the same time,the grains are uniform and coarse, the degree of disseminated tightness decreases,the phenomenon of mutual inclusion is reduced.(3) Additives can improve the activity of FeO, reduce the difficulty of reduction,enhance the process of Fe2+â†'Fe.Additives is also conducive to the formation and growth of crystal grains of iron, so that the rate of reduction of the metal product significantly rises, the maximum amplitude reached nearly30%. With CaF2, Fe2O3, Na2CO3and boron additives (borax, boric anhydride, boric acid, boron mud) added at different temperature, the reduction effect enhance obviously, which Na2CO3and Fe2O3hinder the reduction at1100℃and 1150℃, boron additive for reducing inhibition in1350℃, and CaF2under the experimental conditions were right to restore a facilitating role. The optimum amount of each additive is not the same, wherein the CaF2, borax, boric anhydride, boron mud and the Na2CO3was3%, optimum amount of Fe2O3was5%and the optimum amount of boric acid was7%;(4) The surface of the sample form a dense protective film Fe3O4after water quenched cooling.It can avoid re-oxidation of metallic iron, and effectively improve the metallization ratio of the reduction product. A blank sample(without additives) is particularly significant, more than10%can be improved, especially in the1200～1300℃level the increase can reach16to20%, metallization ratio reached96.82%at1300℃and heating30min; while the samples added CaF2after cooling by water quenching can be improved6.34-11.30%, metallization rate can reach97.75%at1300℃;(5) Iron recovery by magnetic separation of magnetic intensity with basic first increases and then decreases, the optimum magnetic field strength of160kA/m, iron recoveries were more than92%, maximum of iron recovery by natural cooling was98.12%, iron recovery by water quenching was98.74%at1350℃;(6) The effect of temperature on distribution of each element in magnetic product is significantly, with temperature increased, the proportion of magnetic materials, Ti and metallic iron content increases, the proportion of V in the magnetic materials reduce firstly and then increases. When using natural cooling at1350℃except V, the optimal distribution of the elements can be obtained, in which magnetic materials account for91.75%, Fe accounts for83.67%, non-magnetic material of Ti accounts for81.97%, the minimum proportion of V in the magnetic material is55.56%at1200℃. When cooling with water quenching, the data at1300℃is magnetic materials account for92.04%, Fe accounts for87.89%, Ti accounts for79.37%, V in the proportion of magnetic material reaches a minimum56.71%at1150℃;(7) When natural cooling, the magnetic phase is mainly ferrous materials, non-magnetic material is mainly gangue phase. After quenching with water cooling, magnetic product phase reduced, wherein the magnetic material of Fe2O3and Fe3O4disappeared, the non-magnetic materials are TiO2, MgAl2O4, Fe0.5Mg0.5Ti2O5, CaTiO3and V2O3composition;(8) With the reduction product grind size decreases, the proportion of magnetic materials increases, the iron recycling rate first increases and then decreases, when the grind size of58～75μm, the iron recovery reaches the maximum97.78%. Solid-phase reduction and magnetic separation process of Vanadium-titanium magnetite has many advantages, for example,a high degree of utilization, short process, no coke, less pollution, etc.It is applicable to the handling processing of vanadium-titanium magnetite resources.So it can be promoted to application. |
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