Alkali Reductive Roasting of Ilmenite Ore

Abstract

Reductive roasting of ilmenite ore by carbon in the presence of sodium carbonate was carried out at 1000-1200°C for periods of up to 180 min. Additions of sodium carbonate of up to 30 wt% of the ore enhanced the reduction efficiency. The maximum metallization obtained at 1200°C was about 85%, and the rest of the iron exists in the form of sodium-iron-titanates. The type of sodium compound formed in the final product depends on the roasting temperature. The reduction rate data under isothermal conditions were represented by a phase-boundary reaction model for conversions of up to 70 wt%. The apparent activation energy obtained is about 67 kJ Imol. Magnetic separation of roasted products gave different magnetic fractions having different Fe/Ti02 ratios (ranging from 2-3) as well as a non-magnetic fraction that was low in iron and suitable for titanium dioxide production.Resume-Le grillage reductif du minerai d'ilmenite par Ie carbone, en presence du carbonate de sodium, a ete conduit a 1000-1200°C pour des periodes allantjusqu'a 180min. Des additions de carbonate de sodium allant jusqu'a 30% en poids du minerai ont ameliore l'efficacite de la reduction. La metallisation maximum obtenue a 1200°C etait d'environ 85% alors que Ie reste du fer avait la forme de sodium-fer-titanates. Le type de compose de sodium forme dans Ie produit final depend de la temperature de grillage. Les donnees du taux de reduction en conditions isothermales ont ete representees par un modele de reaction de phaselimite pour des conversions jusqu'a 70% en poids. L'activation d'energie apparente obtenue est d'environ 67 kJ Imol. La separation magnetique des produits grilles a donne des fractions magnetiques differentes ayant differents rapports de Fe/Ti02 (entre 2-3) ainsi qu'une fraction non-magnetique qui Hait faible en fer et propice a la production du bioxide de titane.

An assessment of the carbothermic reduction of ilmenite ore by statistical design

“…Splitting the design, Tables 7 and 8, leads to precisely predicting the metallization at low and high factor levels and not at 1100 • C. The slope difference of the contour plots Figs. 6 and 7 confirms our previous findings that the reduction of ilmenite is a complex process and the mixed control equation (phase boundary/gaseous diffusion mechanism) was just fitting the reduction isotherm of ilmenite up to 85% reduction (El-Tawil et al, 1996). Moreover, analyzing the data into a new design at the region 1050-1150 • C, Table 9, where the significant change was expected to occur showed that the model representing the phenomenon in that region is not linear anymore.…”

“…The decrease in weight was employed to calculate the oxygen removed as CO which represents the extent of reduction. The experimental procedure and the reduction isotherms as well as phase compositions of samples are described elsewhere (El-Tawil et al, 1996;Grey et al, 1974).…”

“…However, the model underestimated the metallization % at 1100 • C. The deviation of the model from the experimental results at 1100 • C can be attributed to the change in the reduction mechanism, i.e., presence of more than one mechanism. It was reported (El-Tawil et al, 1996;Grey et al, 1974) that below 1100 • C the reduction of ilmenite proceeds at initially stage of reduction by solid carbon at the contact points between the reactants while above this temperature the reduction depends on the gas-solid reaction. These findings are in agreement with kinetic studies indicating that the boudouard reaction has a significant rate only above 1000 • C (Yuan et al, in press;Kucukkaragoz and Eric, 2006;Walker et al, 1959).…”

“…Carbothermic reduction of ilmenite at temperatures below ∼1200 • C produces metallic iron and reduced form of oxides (Ti n O 2n−1 ) and (Fe, Ti) 3 O 5 (Grey et al, 1973Jones, 1973;El-Tawil et al, 1991, 1993, 1996Grey and Reid, 1974;Pourabdoli et al, 2006). At temperature higher than 1300 • C, the carbothermic reduction has been found to produce liquid carbon saturated iron and titanium oxycarbide (Francis, 1991).…”

Effect of TiO2 on the Crushing Strength and Smelting Mechanism of High-Chromium Vanadium-Titanium Magnetite Pellets

“…[5][6][7][8][9][10][11][12][13][14][15] However, study on high-Cr V-Ti magnetite has been scarce. [2,3,16] Cr 2 O 3 , a refractory oxide, affects the blast furnace reduction and slagging process; furthermore, chromium in molten iron significantly affects the follow-up converter vanadium extraction process.…”