Effects of CaO addition on the reactivity and reaction kinetics of coke

ABSTRACT

In recent years, researches have shown that highly reactive coke for blast furnace ironmaking not only reduces fuel ratio but also reduces carbon emissions. Therefore, the research on developing high reactivity coke has received unprecedented attention. In this work, CaO was added into coals with different degrees of metamorphism to caking coke to study the effect of CaO amount on the non-isothermal gasification reaction behavior of coke. Results showed that the reactivity is significantly improved as the mass of added calcium oxide accounting for less than 0.4% of the dry coal mass. However, CaO exerted little effect on the micro-strength and structural strength of coke. The analysis of Mercury intrusion porosimetry of coke samples demonstrates that the addition of CaO increased the porosity of coke, resulting in the contact area with CO₂, leading further to an increase in coke reactivity. At different heating rates, as the amount of CaO added increased, both the initial reaction temperature and the corresponding temperature of the maximum reaction rate of the gasification from CO₂ decreased little by little. The addition of CaO was increased from 0% to 0.6%, the activation energy of the reaction was decreased by 16.41 kJ/mol. The kinetic model of the gasification of coke by CO₂ conforms to the unreacted shrinking core model. The reaction mechanism function is converted from f(α) = 3(1-α)^2/3 to f(α) = 2(1-α)^1/2 (α means carbon conversion ratio), indicating that the addition of CaO accelerates the dissolution rate of coke by CO₂.

KEYWORDS:

• CaO
• metallurgical coke
• coke gasification reaction
• characteristic parameters
• kinetic

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 22378181), Leading Talents of Science and Technology Innovation in Xingliao Talent Plan, China (Grant No. XLYC2002063), Minmetals Science and Technology Special Program Green Low Carbon Hydrogen Metallurgy Technology and Key Equipment, China (Grant No. 2020ZXA012), and Liaoning Coal Chemical Industry Professional Technology Innovation Center, China (Grant No.USTL201905).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Xiangyun Zhong and Qi Shen: Conceptualization, Methodology, Data curation, and Writing – original draft, Contribute equally to this work; Shiyong Wu and Jinfeng Bai: Supervision, Writing – review & Editing; Guozhong Xu: Supervision, Writing – review & Editing; Mingdeng Wang, Yifei Feng and Zeyu Liu: Project administration.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [22378181]; Minmetals Science and Technology Special Program Green Low Carbon Hydrogen Metallurgy Technology and Key Equipment [2020ZXA012]; Liaoning Coal Chemical Industry Professional Technology Innovation Center [USTL201905]; Leading Talents of Science and Technology Innovation in Xingliao Talent Plan [XLYC2002063].

Notes on contributors

Xiangyun Zhong

Xiangyun Zhong received his master's degree from University of Science and Technology Liaoning in 2008. He is now pursuing a doctoral degree as lecturer of School of chemical engineering, University of Science and Technology Liaoning. His research interests include the preparation and performance evaluation of highly reactive coke, as well as the development of experimental equipment.

Qi Shen

Qi Shen received her master's degree from University of Science and Technology Liaoning in 2023. She is now a technician of Jigang International Engineering& Technology Co., Ltd. Her research is focused on coal quality analysis

Mingdeng Wang

Mingdeng Wang received his bachelor's degree from University of Science and Technology Liaoning in 1992. Currently, he is now Senior Engineer, served as the Deputy Chief Engineer of MCC Jiaonai Engineering Technology Co., Ltd. and the Director of Liaoning Province Low Carbon Coking Professional Technology Innovation Center. He mainly engaged in research on green low-carbon coking technology.

Shiyong Wu

Shiyong Wu received his PH. D from East China University of Science and Technology in 2007. He is now a professor at East China University of Science and Technology. His research interests include t coal gasification and liquefaction, as well as as well as heterogeneous catalysis of carbon materials.

Yifei Feng

Yifei Feng received his master's degree from School of Chemical Engineering, Tianjin University in 2007. Currently, he is now Deputy Senior Engineer, and He mainly engaged in engineering design on getting the coal ready for blending coal.

Zeyu Liu

Zeyu Liu received his master's degree from University of Science andTtechnology Liaoning in 2022. He is now a junior designer of Jigang International Engineering& Technology Co., Ltd. Her research is focused on design of coke oven body and environmental protection process.

Guozhong Xu

Guozhong Xu received his PH. D from Northwestern Polytechnical University in 2008. He is now a professor of School of Chemical Engineering, University of Science and Technology Liaoning. His research interests include the preparation of highly reactive coke, the study of coke thermal properties, and the preparation and application of new coal based coposites.

Jinfeng Bai

Jinfeng Bai received his PH. D from Dalian University of Technology in 2001. He is now a professor of School of Chemical Engineering, University of Science and Technology Liaoning. His research directions include the preparation of highly active coke, the study of coke thermal performance, and the development and application of intelligentcoal blending systems.