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Modeling and simulation of isothermal reduction of a single hematite pellet in gas mixtures of H2 and CO
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2014 (English)In: TMS 2014 143rd Annual Meeting & Exhibition, Annual Meeting Supplemental Proceedings, The Minerals, Metals, and Materials Society, 2014, 495-502 p.Conference paper, Published paper (Refereed)
Abstract [en]

In the present project a time dependent computerized model that fairly accurately simulates the isothermal reduction of a hematite pellet with the use of CO and H2 gas mixtures have been developed. The model, which is based on the Shrinking Core Model (SCM), allows for the description of the chemical reactions taking place and the mass transfer conditions existing for each of the gas species present within the pellet. The equations used to describe the different steps are numerically solved with 1D axial symmetric Finite Element Modeling (FEM) using the commercial COMSOL 4.3b software. Small-scale laboratory experiments were also performed under well-controlled conditions to get an understanding for the weight loss of the pellets as a function of time. The results obtained from these experiments were incorporated into the model. The developed model clearly shows some deviations from the experimental results, but this is believed to be due to the existing variations in the shape and size of the pellets, the porosity distribution and the pelletizing history of the industrial pellets.

Place, publisher, year, edition, pages
The Minerals, Metals, and Materials Society, 2014. 495-502 p.
Series
TMS Annual Meeting
Keyword [en]
Comsol Multiphysics® 4.3b, Hematite, Reduction, Shrinking Core Model (SCM)
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-145480DOI: 10.1002/9781118889879.ch60ISI: 000354941300060Scopus ID: 2-s2.0-84899730997ISBN: 978-111888972-5 (print)OAI: oai:DiVA.org:kth-145480DiVA: diva2:718610
Conference
143rd Annual Meeting and Exhibition, TMS 2014; San Diego, CA; United States; 16 February 2014 through 20 February 2014
Note

QC 20140521

Available from: 2014-05-21 Created: 2014-05-21 Last updated: 2016-11-25Bibliographically approved
In thesis
1. Sustainable Aluminum and Iron Production
Open this publication in new window or tab >>Sustainable Aluminum and Iron Production
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aluminium recycling requires 95% less energy than primary production with no loss of quality. The Black Dross (BD) produced during secondary aluminium production contains high amounts of water-soluble compounds, therefore it is considered as a toxic waste. In the present work, salt removal from BD by thermal treatment has been investigated in laboratory scale. The optimum conditions for treatment were established, i.e., temperature, gas flow rate, holding time, rotation rate, and sample size. The overall degree of chloride removal was established to increase as a function of time and temperature. Even Pretreated Black Dross (PBD) was evaluated as a possible raw material for the production of a calcium aluminate-based ladle-fluxing agent to be used in the steel industry. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e. CaO/Al2O3 ratio, temperature, holding time, and cooling media. The utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results. The iron/steel industry is responsible for 9% of anthropogenic energy and process CO2 emissions. It is believed that the only way to a long-term reduction of the CO2 emissions from the iron/steel industry is commercialization of alternative processes such as Direct Reduction (DR) of iron oxide. Detailed knowledge of the kinetics of the reduction reactions is, however, a prerequisite for the design and optimization of the DR process. To obtain a better understanding of the reduction kinetics, a model was developed step-by-step, from a single pellet to a fixed bed with many pellets. The equations were solved using the commercial software COMSOL Multiphysics®. The final model considers the reaction rate and mass transfer inside the pellet, as well as the mass transfers and heat transfer in the fixed bed. All the models were verified against experimental results, and where found to describe the results in a satisfying way.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 84 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:3
Keyword
Sustainability, Optimization, Black Dross, Salt removal, Steel flux agent, Waste processing, Greenhouse gases, Direct reduction, COMSOL Multiphysics®
National Category
Chemical Engineering
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-196547 (URN)978-91-7729-214-2 (ISBN)
Public defence
2017-01-09, F3, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20161128

Available from: 2016-11-28 Created: 2016-11-15 Last updated: 2016-11-28Bibliographically approved

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