Effects of calcium compounds on the carbothermic reduction of vanadium titanomagnetite concentrate

Effects of calcium compounds on the carbothermic reduction of vanadium titanomagnetite concentrate(VTC) were investigated. It was found that calcium compounds had great effects on the metallization rate of the reduction product, the order of the metallization rate of reduction product being CaCO3 > no additive > CaSO4 > CaCl2, which indicated that the addition of CaCO3 was more conducive to promoting the reduction of iron than other calcium compounds. Gas analysis showed that there were mainly two processes in the carbothermic reduction of VTC, a solid–solid and a solid–gas reaction. The concentrations of CO and CO2 were highest when CaCO3 was added, while that in a roasting system decreased the most when CaCl2 was added. X-ray diffraction(XRD) analysis showed that calcium compounds could change the reduction process of ilmenite in VTC. The phase compositions of the reduction products were changed from metallic iron(Fe) and anosovite(FeTi2O5) to metallic iron(Fe) and perovekite(CaTiO3) when calcium compounds were added. Additionally, CaSO4 and CaCl2 could significantly promote the growth of metallic iron particles, though the existence of Fe-bearing Mg2TiO4 in reduction products was not conducive to the reduction of iron. The formation of FeS would further hinder the reduction of iron after adding CaSO4.

Formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate by adding CaCO3

The formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate(VTC)by adding CaCO3 was investigated.Thermodynamic analysis was employed to show the feasibility of calcium titanate formation by the reaction of ilmenite and Ca CO3 in a reductive atmosphere,where ilmenite is more easily reduced by CO or carbon in the presence of CaCO3.The effects of CaCO3 dosage and reduction temperature on the phase transformation and metallization degree were also investigated in an actual roasting test.Appropriate increase of CaCO3 dosages and reduction temperatures were found to be conducive to the formation of calcium titanate,and the optimum conditions were a CaCO3 dosage of 18 wt%and a reduction temperature of 1400°C.Additionally,scanning electron microscopy–energy dispersive spectrometry(SEM–EDS)analysis shows that calcium titanate produced via the carbothermic reduction of VTC by CaCO3 addition was of higher purity with particle size approximately 50μm.Hence,the separation of calcium titanate and metallic iron will be the focus in the future study.

Influences of Technological Parameters on Smelting-separation Process for Metallized Pellets of Vanadium-bearing Titanomagnetite Concentrates

The smelting-separation process for metallized pellets of vanadium-bearing titanomagnetite concentrates was studied.The influences of smelting temperature,smelting time,and the basicity of the metallized pellet on vanadium and iron recovery were investigated.The characteristics of titanium slag were analyzed using X-ray diffraction,energy dispersive spectroscopy,and mineralographic microscopic analysis.The results demonstrate that appropriate increases in smelting temperature and smelting time can improve the vanadium and iron recovery from metallized pellets and are beneficial for the slag-iron separation.Although increasing the basicity of the metallized pellet can considerably improve the vanadium and iron recovery,the TiO;grade of titanium slag was decreased.Under the optimal conditions,90.17% of vanadium and 92.98% of iron in the metallized pellet were recovered,and the TiO;grade of titanium slag was 55.01%.It was found that anosovite,augite,spinel,glassiness,and metallic iron were the main mineral phases of the titanium slag.

Amelioration of the mineral compositions and microstructures of the special ore sinters

Mineral compositions and microstructures of fluorine bearing magnetite concentrate and vanadium titanomagnetite concentrate are studied. The results show that a boride and a catalytic oxidation agent have great effects on ameliorating the mineral compositions and microstructures of these sinters, and the catalytic agent is more effective. Comparing these two kinds of ores, the performance of fluorine bearing magnetite concentrate is better. Addition of 0.01% catalyst into fluorine bearing magnetite concentrate can increase calcium ferrite content from 15% 20% up to 34% 39%, and its microstructure changes from large cavities and thin framework into intermediate cavities and thick framework, and the microcracks disappear.