Change search
ReferencesLink to record
Permanent link

Direct link
Sustainable Aluminum and Iron Production
KTH, School of Chemical Science and Engineering (CHE), Chemistry.ORCID iD: 0000-0001-5803-5933
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 [en]
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: urn:nbn:se:kth:diva-196547ISBN: 978-91-7729-214-2OAI: oai:DiVA.org:kth-196547DiVA: diva2:1049593
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
List of papers
1. Black Dross: Processing Salt Removal from Black Dross by Thermal Treatment
Open this publication in new window or tab >>Black Dross: Processing Salt Removal from Black Dross by Thermal Treatment
2014 (English)In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 66, no 11, 2243-2252 p.Article in journal (Refereed) Published
Abstract [en]

The salt removal from black dross by thermal treatment has experimentally been studied under different conditions in both a stationary resistance furnace and in a laboratory scale rotary furnace. The experiments were designed based on partial pressure calculations using the Thermo-Calc software (Thermo-Calc Software, Stockholm, Sweden). The salt removal efficiency was evaluated by scanning electron microscope (SEM) energy-dispersive x-ray spectroscopy and x-ray diffraction analyses, and the optimum conditions for treatment 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, as well as by reduced pressure. Under atmospheric pressure, the highest degree of chloride removal from a 20 g sample was obtained after 10 h at 1523 K resulting in a 98% removal and a final chloride content of 0.3 wt.% in the residue. Under reduced pressure, the chloride concentrate was lowered to 0.2 wt.% after thermal treatment of a 20 g sample at 1473 K for 8 h. In the case of 200 g samples treated in a rotary furnace, the chloride concentrate was 2.5 wt.% after 14 h at 1523 K, representing a removal of 87%. Below 0.3 wt.% chloride content, the material is deemed a nonhazardous waste.

Keyword
Aluminum Dross, Cake, Management
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-157607 (URN)10.1007/s11837-014-1178-6 (DOI)000344618900016 ()2-s2.0-84925483060 (ScopusID)
Note

QC 20141212

Available from: 2014-12-12 Created: 2014-12-11 Last updated: 2016-11-25Bibliographically approved
2. Black Dross Processing: Utilization of Black Dross in the Production of a Ladle Fluxing Agent
Open this publication in new window or tab >>Black Dross Processing: Utilization of Black Dross in the Production of a Ladle Fluxing Agent
2016 (English)In: Journal of Sustainable Metallurgy, ISSN 2199-3831Article in journal (Refereed) Published
Abstract [en]

In the present study, black dross (BD) residue, a hazardous by-product generated during secondary aluminum production, has been 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 thermally treated BD [pretreated black dross (PBD)] used as a starting material, consisted of approximately 49.5 ± 3.5 wt% alumina and 0.3 wt% chloride. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e., the CaO/Al2O3 ratio, the sintering temperature and time, and the cooling medium. The prepared samples were all sintered in a rapid high-temperature inductive furnace, and later characterized by SEM–EDS, XRD, XRF, and DTA/TG analyses. Dissolution tests were also performed using a synthetic slag simulating the carryover. Based on the presently obtained results, it can be concluded that the utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results, and the optimum process conditions were established to be 1523 K for 15 min as the sintering temperature and time, water as the cooling medium, and a CaO/Al2O3 ratio of 0.94. Utilizing PBD as a raw material in the production of a value-added product would significantly reduce the need for the disposal of BD as a waste, and thereby help to decrease the overall environmental impact. It would also provide economic benefit to both the steel and aluminum industry.

Place, publisher, year, edition, pages
Springer, 2016
Keyword
Aluminum, Pretreated black dross (PBD), Fluxing agent, Calcium aluminate
National Category
Materials Engineering
Research subject
Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-196541 (URN)10.1007/s40831-016-0076-2 (DOI)
Note

QC 20161117

Available from: 2016-11-15 Created: 2016-11-15 Last updated: 2016-11-25Bibliographically approved
3. Modeling and simulation of isothermal reduction of a single hematite pellet in gas mixtures of H2 and CO
Open this publication in new window or tab >>Modeling and simulation of isothermal reduction of a single hematite pellet in gas mixtures of H2 and CO
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 (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
Series
, TMS Annual Meeting
Keyword
Comsol Multiphysics® 4.3b, Hematite, Reduction, Shrinking Core Model (SCM)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-145480 (URN)10.1002/9781118889879.ch60 (DOI)000354941300060 ()2-s2.0-84899730997 (ScopusID)978-111888972-5 (ISBN)
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
4. Reduction of commercial hematite pellet in isothermal fixed bed-experiments and numerical modelling
Open this publication in new window or tab >>Reduction of commercial hematite pellet in isothermal fixed bed-experiments and numerical modelling
2016 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 43, no 1, 31-38 p.Article in journal (Refereed) Published
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
Keyword
Hematite, Gas-solid reaction, Mass transfer, Shrinking core model, Kinetics
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-183344 (URN)10.1179/1743281215Y.0000000046 (DOI)000369983200005 ()2-s2.0-84961673951 (ScopusID)
Note

QC 20160307

Available from: 2016-03-07 Created: 2016-03-07 Last updated: 2016-11-25Bibliographically approved
5. Reduction kinetics of commercial haematite pellet in a fixed bed at 1123-1273 K
Open this publication in new window or tab >>Reduction kinetics of commercial haematite pellet in a fixed bed at 1123-1273 K
2016 (English)In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 43, no 5, 394-402 p.Article in journal (Refereed) Published
Abstract [en]

In the present study a model for future use in the modelling of moving bed direct reduction reactors has been developed. The model of a fixed bed reactor for the production of sponge iron from haematite incorporates both heat-and mass-transfer, as well as the chemical reduction rate. The model results were compared to the experimental data obtained from a lab scale reactor in the temperature range 1123-1273 K, as well as to the output from a simple model assuming isothermal conditions. The H-2/CO ratio (beta) of the reducing gas was in all cases varied from 0.8 to 2.0. Overall the non-isothermal model developed permits a more accurate representation of the experimental data than the isothermal estimates, with a typical discrepancy of only 1.3%.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keyword
Fixed bed, Shrinking Core Model, Gas-solid reaction, Heat transfer, Direct reduction, Kinetics, Haematite
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-191762 (URN)10.1080/03019233.2015.1104072 (DOI)000380274000009 ()2-s2.0-84982291595 (ScopusID)
External cooperation:
Note

QC 20160902

Available from: 2016-09-02 Created: 2016-09-02 Last updated: 2016-11-25Bibliographically approved

Open Access in DiVA

fulltext(2731 kB)20 downloads
File information
File name FULLTEXT01.pdfFile size 2731 kBChecksum SHA-512
46fd308e2fa4b6ad1011d965b2e5580c4b2c0356f58f10bd82eb4bce2e08fa8fbc43234021ebc21b7f74cf3c437311541d68e7773f2bb9c9d214d6e03ec9049a
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Beheshti, Reza
By organisation
Chemistry
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 20 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 247 hits
ReferencesLink to record
Permanent link

Direct link