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Reduction of commercial hematite pellet in isothermal fixed bed-experiments and numerical modelling
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Nothern Research Institute Narvik, Norway.
2016 (Engelska)Ingår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 43, nr 1, s. 31-38Artikel i tidskrift (Refereegranskat) Published
Resurstyp
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.

Ort, förlag, år, upplaga, sidor
Taylor & Francis, 2016. Vol. 43, nr 1, s. 31-38
Nyckelord [en]
Hematite, Gas-solid reaction, Mass transfer, Shrinking core model, Kinetics
Nationell ämneskategori
Metallurgi och metalliska material
Identifikatorer
URN: urn:nbn:se:kth:diva-183344DOI: 10.1179/1743281215Y.0000000046ISI: 000369983200005Scopus ID: 2-s2.0-84961673951OAI: oai:DiVA.org:kth-183344DiVA, id: diva2:909582
Anmärkning

QC 20160307

Tillgänglig från: 2016-03-07 Skapad: 2016-03-07 Senast uppdaterad: 2017-11-30Bibliografiskt granskad
Ingår i avhandling
1. Sustainable Aluminum and Iron Production
Öppna denna publikation i ny flik eller fönster >>Sustainable Aluminum and Iron Production
2017 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2017. s. 84
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:3
Nyckelord
Sustainability, Optimization, Black Dross, Salt removal, Steel flux agent, Waste processing, Greenhouse gases, Direct reduction, COMSOL Multiphysics®
Nationell ämneskategori
Kemiteknik
Forskningsämne
Kemi
Identifikatorer
urn:nbn:se:kth:diva-196547 (URN)978-91-7729-214-2 (ISBN)
Disputation
2017-01-09, F3, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20161128

Tillgänglig från: 2016-11-28 Skapad: 2016-11-15 Senast uppdaterad: 2016-11-28Bibliografiskt granskad

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