Thermal performance and reduction kinetic analysis of cold-bonded pellets with CO and H<sub>2</sub> mixtures

Rong-rong Wang; Jian-liang Zhang; Yi-ran Liu; An-yang Zheng; Zheng-jian Liu; Xing-le Liu; Zhan-guo Li

doi:10.1007/s12613-018-1623-6

Volume 25 Issue 7

Jul. 2018

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Article Navigation > International Journal of Minerals, Metallurgy and Materials > 2018 > 25(7): 752-761

Rong-rong Wang, Jian-liang Zhang, Yi-ran Liu, An-yang Zheng, Zheng-jian Liu, Xing-le Liu, and Zhan-guo Li, Thermal performance and reduction kinetic analysis of cold-bonded pellets with CO and H₂ mixtures, Int. J. Miner. Metall. Mater., 25(2018), No. 7, pp. 752-761. https://doi.org/10.1007/s12613-018-1623-6

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Rong-rong Wang, Jian-liang Zhang, Yi-ran Liu, An-yang Zheng, Zheng-jian Liu, Xing-le Liu, and Zhan-guo Li, Thermal performance and reduction kinetic analysis of cold-bonded pellets with CO and H2 mixtures, Int. J. Miner. Metall. Mater., 25(2018), No. 7, pp. 752-761. https://doi.org/10.1007/s12613-018-1623-6

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Research Article

Thermal performance and reduction kinetic analysis of cold-bonded pellets with CO and H₂ mixtures

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Corresponding author:
Zheng-jian Liu E-mail: liuzhengjian@ustb.edu.cn
Received: 18 January 2018; Revised: 14 March 2018; Accepted: 20 March 2018

Abstract

Abstract

Cold-bonded pellets, to which a new type of inorganic binder was applied, were reduced by H₂–CO mixtures with different H₂/CO molar ratios (1:0, 5:2, 1:1, 2:5, and 0:1) under various temperatures (1023, 1123, 1223, 1323, and 1423 K) in a thermogravimetric analysis apparatus. The effects of gas composition, temperature, and binder ratio on the reduction process were studied, and the microstructure of reduced pellets was observed by scanning electron microscopy–energy-dispersive spectrometry (SEM-EDS). The SEM-EDS images show that binder particles exist in pellets in two forms, and the form that binder particles completely surround ore particles has a more significant hinder effect on the reduction. The reduction equilibrium constant, effective diffusion coefficient, and the reaction rate constant were calculated on the basis of the unreacted core model, and the promotion effect of temperature on reduction was further analyzed. The results show that no sintering phenomenon occurred at low temperatures and that the increasing reaction rate constant and high gas diffusion coefficient could maintain the promotion effect of temperature; however, when the sintering phenomenon occurs at high temperatures, gas diffusion is hindered and the promotion effect is diminished. The contribution of the overall equilibrium constant to the promotion effect depends on the gas composition.
- cold-bonded pellets;
- inorganic binder;
- reduction fraction;
- reduction kinetic model;
- sintering phenomenon

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