A Sustainable Strategy for Spent Cathode Carbon Blocks Hazardous Waste Recycling Using Binary Molten Salt Thermal Treatment

  • LI Bin ,
  • DING Yan ,
  • JIAO Yuyong ,
  • XU Fang ,
  • WANG Xinyang ,
  • ZHENG Fei ,
  • ZOU Junpeng ,
  • GAO Qiang ,
  • HU Hongyun
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  • 1. Faculty of Engineering, China University of Geosciences, Wuhan 430074, China
    2. Institute for Natural Disaster Risk Prevention and Emergency Management, China University of Geosciences, Wuhan 430074, China
    3. State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China

Online published: 2024-04-30

Supported by

This research was supported by the “CUG Scholar” scientific Research Funds at China University of Geosciences (Wuhan) (Project No. 2020088), National Natural Science Foundation of China (No. 41920104007), and Opening Fund of State Key Laboratory of Fire Science, University of Science and Technology of China (No. HZ2023-KF03).

Copyright

Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2024

Abstract

Waste-to-Energy treatment is a promising path to environment and energy management in the future. This work detailed a binary molten salt thermal treatment methodology for the detoxification of spent cathode carbon block (SCCB) waste and the recycling of carbonaceous materials. The thermal behavior of SCCB and SCCB blended with molten salts was investigated. It was found that the NaCl-Na2CO3 binary molten salts significantly contributed to reducing pyrolysis onset temperature by 334.3 K compared to that of SCCB itself (i.e., activation energy of pyrolysis reaction was reduced from 4.24×105 to 2.30×105 J/mol), thus helping to lower thermal treatment energy consumption. With the addition of binary molten salts, the residue after thermal treatment in a horizontal tube furnace experiment was separated into two layers. The bottom-layer residue was mainly composed of molten salts. The fluorine content in the form of NaF and CaF2 of top-layer residue was reduced significantly while the carbon content remained unchanged. Specifically, the leaching concentration of fluoride ion was decreased from 4620 mg/L to 856 mg/L. It is noted that the NaF and CaF2 can be removed through water-leaching and hydrothermal acid-leaching methods and thus the carbonaceous materials with a calorific value of 17.5 MJ/kg were obtained.

Cite this article

LI Bin , DING Yan , JIAO Yuyong , XU Fang , WANG Xinyang , ZHENG Fei , ZOU Junpeng , GAO Qiang , HU Hongyun . A Sustainable Strategy for Spent Cathode Carbon Blocks Hazardous Waste Recycling Using Binary Molten Salt Thermal Treatment[J]. Journal of Thermal Science, 2024 , 33(3) : 1082 -1093 . DOI: 10.1007/s11630-024-1952-x

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