University of Oulu

Koskela, A., Suopajärvi, H., & Fabritius, T. (2022). Interaction between coal and lignin briquettes in co-carbonization. Fuel, 324, 124823.

Interaction between coal and lignin briquettes in co-carbonization

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Author: Koskela, Aki1; Suopajärvi, Hannu2; Fabritius, Timo1
Organizations: 1Process Metallurgy, Faculty of Technology, University of Oulu, Oulu, Finland
2Sapotech Oy, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 8.3 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2022-11-29


The utilization of bio-based side streams in metallurgical coke making promotes two major factors in the mitigation of climate impact in the steel industry. Circular economy as the waste material from biorefinery industry is utilized as a raw material in the steel industry, and mitigation of the production of fossil-based CO2 emissions. In this work, lignin from the hydrolysis process was used in a briquetted form as part of the raw material blend in metallurgical coke making. For the experiments and analyses, lignin briquettes were pyrolyzed at 450, 600 and 1200 °C, while one sample was left non-pyrolyzed. In the co-carbonization of briquetted lignin, lignin chars and bituminous coal, the focus was to evaluate the interaction between char and coal in the carbonization. This was studied by thermogravimetric analysis (TGA), optical dilatometry, and light optical microscopy. The results suggested that the interaction between the coal and lignin reduced when the pyrolysis temperature of the briquettes, prior to co-carbonization, was elevated. This was due to the decrease of overlapping of the pyrolysis rates of chars and coking coal. Combined with the dilation and shrinking behaviour of the chars, presented in this paper, separate char and coke structures were formed in the final coke in co-carbonization.

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Series: Fuel
ISSN: 0016-2361
ISSN-E: 1873-7153
ISSN-L: 0016-2361
Volume: 324
Article number: 124823
DOI: 10.1016/j.fuel.2022.124823
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
Funding: The Carbotech project (project number A75548), funded by European Regional Development Fund (ERDF) is acknowledged by the authors of this paper. The authors would like to thank SSAB Europe, Raahe for providing the coking coal and ST1, Kajaani for providing hydrolysis lignin for the experiments that are presented in this work. Tommi Kokkonen and Riku Mattila from the Process Metallurgy Research Group from the University of Oulu are acknowledged for their help in the execution of the laboratory experiments and analyses that are presented in this work. The machine shop staff of the Materials and Mechanical Engineering Research Group from the University of Oulu is acknowledged for making the parts for the coking device and providing access to their machine shop facilities and hydraulic press for the compression of hydrolysis lignin mini briquettes.
Copyright information: © 2022 The Authors. This is an open access article under the CC BY license (