Oxidation pathway and kinetics of titania slag powders during cooling process in air

Abstract

The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry (DSC) and thermogravimetry (TG). The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves. The isothermal oxidation kinetics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method. The results revealed that the entire isothermal oxidation process comprises two stages. The kinetic mechanism of the first stage can be described as f (α) = 1.77(1 − α)[−ln(1 − α)]^{(1.77 − 1)/1.77}, f (α) = 1.97(1 − α)[−ln(1 − α)]^{(1.97−1)/1.97}, and f (α) = 1.18(1 − α)[−ln(1 − α)]^{(1.18−1)/1.18}. The kinetic mechanism of the second stage for all samples can be described as f (α) = 1.5(1 − α)^2/3[1 − (1 − α)^1/3]⁻¹. The activation energies of titania slag powders with different sizes (d ₁ < 0.075 mm, 0.125 mm < d ₂ < 0.150 mm, and 0.425 mm < d ₃ < 0.600 mm) for different reaction degrees were calculated. For the given experimental conditions, the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction. The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion (for powders d ₁ < 0.075 mm) and internal diffusion (for powders 0.125 mm < d ₂ < 0.150 mm and 0.425 mm < d ₃ < 0.600 mm).

Keywords

high titania slag powder / oxidation pathway / isothermal oxidation kinetics / ln-ln analysis / activation energy / rate-controlling step

References

[1] Zhang YJ, Qi T, Zhang Y. A novel preparation of titanium dioxide from titanium slag. Hydrometallurgy, 2009, 96(1–2): 52.

[2] Lee KM, Park PJ. Estimation of the environmental credit for the recycling of granulated blast furnace slag based on LCA. Resour. Conserv. Recycl., 2005, 44(2): 139.

[3] Pickering SJ, Hay N, Roylance TF, Thomas GH. New process for dry granulation and heat recovery from molten blast-furnace slag. Ironmaking Steelmaking, 1985, 12(1): 14.

[4] Mizuochi T, Akiyama T, Shimada T, Kasai E, Yagi JI. Feasibility of rotary cup atomizer for slag granulation. ISIJ Int., 2001, 41(12): 1423.

[5] Kashiwaya Y, In-Nami Y, Akiyama T. Development of a rotary cylinder atomizing method of slag for the production of amorphous slag particles. ISIJ Int., 2010, 50(9): 1245.

[6] Kashiwaya Y, In-Nami Y, Akiyama T. Mechanism of the formation of slag particles by the rotary cylinder atomization. ISIJ Int., 2010, 50(9): 1252.

[7] Deng GZ, Chen X. The oxidation of high titania slag. Iron Steel Vanadium Titanium, 1985, 2, 41.

[8] Li LS, Li GQ, Lou TP, Che YC, Sui ZT. Study on oxidation kinetics of Ti-enriched slag by electromotive force. Acta Metall. Sin., 2000, 36(6): 642.

[9] Zhang L, Li GQ, Sui ZT. Oxidation kinetics of titaniferous slag. Chin. J. Nonferrous Met., 2002, 12(5): 1069.

[10] Przepiera A, Jabłoński M. Thermal transformations of high titania slag of high titania content. J. Therm. Anal. Calorim., 2003, 74, 631.

[11] Samal S, Mohapatra BK, Mukherjee PS, Chatterjee SK. Integrated XRD, EPMA and XRF study of ilmenite and titania slag used in pigment production. J. Alloys Compd., 2009, 474(1–2): 484.

[12] Samal S, Mohapatra BK, Mukherjee PS. The effect of heat treatment on titania slag. J. Miner. Mater. Charact. Eng., 2010, 9(9): 795.

[13] Khawam A, Flanagan DR. Solid-state kinetic models: basics and mathematical fundamentals. J. Phys. Chem. B, 2006, 110(35): 17315.

[14] Sheu HH, Hsiung LC, Sheu JR. Synthesis of multiphase intermetallic compounds by mechanical alloying in Ni-Al-Ti system. J. Alloys Compd., 2009, 469(1–2): 483.

[15] Shen YP, Hng HH, Oh JT. Formation kinetics of Ni-15% Fe-5% Mo during ball milling. Mater. Lett., 2004, 58(22–23): 2824.

[16] Li CX, Lv XW, Chen J, Liu XY, Bai CG. Kinetics of titanium nitride synthesized with Ti and N₂. Int. J. Refract. Met. Hard Mater., 2015, 52, 165.

[17] Tan SS, Su AH, Li WH, Zhou EL. New insight into melting and crystallization behavior in semicrystalline poly(ethylene terephthalate). J. Polym. Sci. Part B, 2000, 38(1): 53.

[18] Lin Q, Chen N, Ye W, Liu RM. Kinetics of hydrogen absorption in hydrogen storage alloy. Int. J. Miner. Metall. Mater., 1997, 4(2): 34.

[19] Hancock JD, Sharp JH. Method of comparing solid-state kinetic data and its application to the decomposition of kaolinite, brucite, and BaCO₃. J. Am. Ceram. Soc., 1972, 55(2): 74.

[20] Koga N. Kinetic analysis of thermoanalytical data by extrapolating to infinite temperature. Thermochim. Acta, 1995, 258, 145.

[21] Šesták J. Diagnostic limits of phenomenological kinetic models introducing the accommodation function. J. Therm. Anal. Calorim., 1990, 36(6): 1997.

[22] Ozao R, Ochiai M. Fractal reaction in solids: Reaction functions reconsidered. J. Ceram. Soc. Jpn., 1993, 101(3): 263.

[23] Koga N, Malek J, Sestak J, Tanaka H. Data treatment in non-isothermal kinetics and diagnostic limits of phenomenological models. Netsu Sokutei, 1993, 20(4): 210.

[24] Gao XD, Wang JS, Lv W, Xiang JY, Lv XW. The isothermal reduction kinetics of chromium-bearing vanadium-titanium magnetite sinter. Can. Metall. Q., 2019, 58(2): 177.

[25] Mccune RC, Wynblatt P. Calcium segregation to a magnesium oxide (100) surface. J. Am. Ceram. Soc., 1983, 66, 111.

[26] Tang J, Chu MS, Li F, Tang YT, Liu ZG, Xue XX. Reduction mechanism of high-chromium vanadium-titanium magnetite pellets by H₂-CO-CO₂ gas mixtures. Int. J. Miner. Metall. Mater., 2015, 22(6): 562.

[27] Ding CY, Lv XW, Xuan SW, Tang K, Bai CG. Isothermal reduction kinetics of powdered hematite and calcium ferrite with CO-N₂ gas mixtures. ISIJ Int., 2016, 56(12): 2118.