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Reduction of commercial hematite pellet in isothermal fixed bed-experiments and numerical modelling
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Nothern Research Institute Narvik, Norway.
2016 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 43, no 1, 31-38 p.Article in journal (Refereed) Published
Resource type
Text
Abstract [en]

In the present work, fixed bed reduction experiments were conducted at 1173 K over a range of H-2/CO ratios from 0.8 to 2.0 and subsequently modelled numerically (R). The model consists of two one-dimensional, isothermal and time dependent models. The gas-solid reactions were kinetically modelled using a modified shrinking core approach, and the equations were solved using the commercial software COMSOL Multiphysics H. The simulation results agree with thermal gravity experimental data with an average difference of 2.5%. A sensitivity analysis was conducted using the numerical model to establish the optimum operational conditions. The effects of the reducing gas ratio and flow rate, pellet radius and porosity, and the total bed height on the overall degree of reduction were also investigated.

Place, publisher, year, edition, pages
Taylor & Francis, 2016. Vol. 43, no 1, 31-38 p.
Keyword [en]
Hematite, Gas-solid reaction, Mass transfer, Shrinking core model, Kinetics
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-183344DOI: 10.1179/1743281215Y.0000000046ISI: 000369983200005Scopus ID: 2-s2.0-84961673951OAI: oai:DiVA.org:kth-183344DiVA: diva2:909582
Note

QC 20160307

Available from: 2016-03-07 Created: 2016-03-07 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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