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Lundgren, Maria
Publications (10 of 12) Show all publications
Lundgren, M., Khanna, R. N., Ökvist, L. S., Sahajwalla, V. & Björkman, B. (2014). The Evolution of Structural Order as a Measure of Thermal History of Coke in the Blast Furnace (ed.). Paper presented at . Metallurgical and materials transactions. B, process metallurgy and materials processing science, 45(2), 603-616
Open this publication in new window or tab >>The Evolution of Structural Order as a Measure of Thermal History of Coke in the Blast Furnace
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2014 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 45, no 2, p. 603-616Article in journal (Refereed) Published
Abstract [en]

Investigations were carried out on cokes heat treated in the laboratory and on cokes extracted from the experimental blast furnace (EBF) raceway and hearth. X-ray diffraction (XRD) measurements were performed to investigate changes in structural order (Lc), chemical transformations in coke ash along with comparative thermodynamic equilibrium studies and the influence of melt. Three data processing approaches were used to compute Lc values as a function of temperature and time and linear correlations were established between Lc and heat treatment temperatures during laboratory investigations. These were used to estimate temperatures experienced by coke in various regions of EBF and estimated raceway temperatures were seen to follow the profile of combustion peak. The MgAl2O4 spinel was observed in coke submerged in slag during laboratory studies and in cokes found further into the raceway. Coke in contact with hot metal showed XRD peaks corresponding to presence of Fe3Si. The intensity of SiO2 peak in coke ash was seen to decrease with increasing temperature and disappeared at around 1770 K (1500 °C) due to the formation of SiC. This study has shown that the evolution of structural order and chemical transformations in coke could be used to estimate its thermal history in blast furnaces.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-4507 (URN)10.1007/s11663-013-9977-7 (DOI)000336980600034 ()2-s2.0-84899430650 (Scopus ID)272fb233-5351-43bc-ab6b-794fef3fccde (Local ID)272fb233-5351-43bc-ab6b-794fef3fccde (Archive number)272fb233-5351-43bc-ab6b-794fef3fccde (OAI)
Note
Validerad; 2014; 20131112 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lundgren, M. (2013). Development of coke properties during the descent in the blast furnace (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Development of coke properties during the descent in the blast furnace
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The efficiency in use of reducing agents in blast furnace (BF) ironmaking has been significantly improved over the years. At most blast furnaces, auxiliary fuels are injected to replace some of the coke. To further reduce carbon consumption, prevention of losses and modification of raw materials or process conditions are required. In this study coke properties, their development during the descent in the BF under different process conditions, contribution to off-gas dust as well as modifications of coke aiming for reduced energy consumption in the BF have been investigated. The changes in chemical composition of coke ash, mineral phase developments and coke participation in the endothermic gasification reaction with CO2 and coke graphitisation were studied. Also, in order to reduce the losses of material in the off-gas, a characterisation of the off-gas dust and its connection to BF conditions and coke property development in the BF has been made. Coke properties have been studied in the laboratory and in samples taken out from different parts of the LKAB Experimental BF (EBF®) during varied operational set-ups. Properties of coke from the BF high-temperature region were studied via tuyere core-drilling of samples from the EBF and an industrial-scale BF.The results showed that the coarser dry flue dust is mechanically formed. Coke fines originating from the upper shaft dominates the coarser fractions. Gasification in the shaft has a negligible effect on the high quality coke used in the EBF. The finer dust fraction, sludge, consists mainly of chemically formed spherical particles in the order of <1 μm. Gaseous compounds formed in the BF high-temperature area precipitate from the ascending gas as the temperature decreases. Flow conditions in the top of the BF and the fluidisation properties of fine particles determine out-flow of off-gas dust. Low off-gas temperatures, and thus lower off-gas velocities, are favourable for low flue dust amounts expelled from the blast furnace. The strength and reactivity of coke at high temperature, measured in the standardised test, was compared with coke from basket samples charged into the EBF. Coke reactivity in the EBF is considerably lower for all coke types studied compared to coke studied in the CRI/CSR test. Due to higher gasification in the laboratory test the ash content is higher in that test. However, gaseous components in the EBF, such as recirculated alkali, contribute to changed ash composition in BF coke. Laboratory studies using fixed bed reactor (FBR) and a thermo gravimetric analyser (TGA) on the same material, original as well as Fe- and Ca-activated coke samples, identified the effects on reaction behaviour and were the basis for selection of the potentially best method for activating nut coke to achieve higher reactivity with CO2 when charged into iron-bearing layers. All types of Fe- and Ca-containing activation agents used increase the apparent reaction rates for coke with low reactivity and contents of catalytic components in the ash. Activation with a solution of Fe(NO3)3 has the strongest effect on the reactivity, followed by slurry of Ca(OH)2 and iron oxides (Fe2O3 and Fe3O4) in descending order. Use of a non-specific weight loss in TGA as a basis for apparent reaction rate demands measurements in a temperature interval free from other reactions involving the activation agents. The reaction rate is reduced when CO is present in the reaction gas. Aiming for a method for determination of thermal history in BF samples the correlation between temperature and coke graphitisation was studied using three different data processing methods for removing the influence from overlapping peaks during X-ray diffraction measurements. Structural changes in coke during heat treatment are accompanied by chemical transformations in ash compounds and changed the pattern of disturbing peaks. Key ash phases were SiO2 and mullite. At high temperatures (~1500°C) the SiO2 peaks are reduced in magnitude and finally disappear to be replaced with SiC peaks. The graphitisation was correlated with temperature and time in argon atmosphere and the impact from hot metal and slag was investigated. The graphitisation degree in coke samples from the EBF raceway and hearth was estimated and the evolution of structural order was found to be suitable in order to estimate the thermal history of coke in blast furnaces.Gaseous compounds formed in the BF high temperature area are precipitated from the ascending gas as the temperature is decreased. Flow conditions in the top of the BF and the fluidisation properties of fine particles determine out-flow of off-gas dust. Low off-gas temperatures, and thus lower off-gas velocities, are favourable for low flue dust amounts expelled from the blast furnace. The strength and reactivity of coke at high temperature, measured in the CSR/CRI test was compared with coke from charged basket samples into the EBF. Coke reactivity in the EBF was considerably lower for all coke types studied compared to in the CRI/CSR test. Due to higher gasification in the laboratory test the ash content was higher in the test. However, gaseous components in the EBF such as recirculated alkali contribute to changed ash composition in BF coke. Laboratory studies using fixed bed reactor (FBR) and thermal gravimetric analysis (TGA) on the same material of original as well as Fe- and Ca-activated coke samples stated the effects on reaction behaviour and were the basis for selection of the potentially best method for activating nut coke to achieve higher reactivity with CO2 when charged into iron bearing layers. All types of Fe and Ca containing activation agents used increased the apparent reaction rates for coke with low reactivity and contents of catalytic components in the ash. Activation with a solution of Fe(NO3)3 had the strongest effect on the reactivity, followed by slurry of Ca(OH)2 and iron oxides (Fe2O3 and Fe3O4) in descending order. Use of a non-specific weight loss in TGA as basis for apparent reaction rate demands measurements in a temperature interval free from other reactions involving the activation agents. The reaction rate was reduced when CO was present in the reaction gas. Aiming for a method for determination of thermal history in BF samples the correlation between temperature coke graphitisation degrees was studied using three different data processing methods for remove the influence overlapping peaks during X-ray diffraction measurements. Structural changes in coke during heat treatment were accompanied by chemical transformations in ash compounds and changed the pattern of disturbing peaks. Key ash phases were SiO2 and mullite. At high temperatures ~1500°C the SiO2 peak are reduced in magnitude and finally disappear to be replaced with SiC peaks. The graphitisation could be correlated with the temperature and time in argon atmosphere as well and the impact from hot metal and slag. Coke samples from the EBF raceway and hearth were also measured and estimated and the evolution of structural order was found to be suitable in order to estimate the thermal history of coke in blast furnaces.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2013. p. 112
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-17356 (URN)3027b99f-4d6c-45ca-9af4-1c822717a596 (Local ID)978-91-7439-762-8 (ISBN)978-91-7439-763-5 (ISBN)3027b99f-4d6c-45ca-9af4-1c822717a596 (Archive number)3027b99f-4d6c-45ca-9af4-1c822717a596 (OAI)
Note
Godkänd; 2013; 20131003 (lunmar); Tillkännagivande disputation 2013-11-06 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Maria Lundgren Ämne: Processmetallurgi/Process Metallurgy Avhandling: Development of Coke Properties during the Descent in the Blast Furnace Opponent: Professor emeritus Seshadri Seetharaman, Kungliga Tekniska Högskolan, Stockholm Ordförande: Professor Bo Björkman, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 29 november 2013, kl 10.00 Plats: F341, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, M., Ökvist, L. S., Hyllander, G., Jansson, B. & Björkman, B. (2012). High temperature coke characteristics in the blast furnace: evaluation of coke properties in the raceway area (ed.). In: (Ed.), (Ed.), Scanmet IV: 4th International Conference on Process Development in Iron and Steelmaking. Paper presented at International Conference on Process Development in Iron and Steelmaking : 10/06/2012 - 13/06/2012 (pp. 157-168). Luleå: MEFOS, 2
Open this publication in new window or tab >>High temperature coke characteristics in the blast furnace: evaluation of coke properties in the raceway area
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2012 (English)In: Scanmet IV: 4th International Conference on Process Development in Iron and Steelmaking, Luleå: MEFOS , 2012, Vol. 2, p. 157-168Conference paper, Published paper (Refereed)
Abstract [en]

Core-drilling into the coke bed of raceway and hearth has been performed in the LKAB Experimental Blast Furnace (EBF®) during short stoppages aiming to characterize raceway conditions corresponding to different operational conditions. All coke operation, injection of pulverized coal and injection of a mixture of coal and blast furnace flue dust (BFD) were evaluated and compared. The samples have been studied regarding particle size and distribution, coke have been evaluated with chemical composition and thermal history, i.e. coke graphitization degree. In addition, the results have been compared to drilled raceway core samples from SSAB industrial blast furnace in Luleå. Coke in drill-cores consists of bosh, raceway and deadman coke. In comparison with charged coke this coke has changed characteristics depending on the exposed conditions which vary along the radius of each drilled core. Coke in raceway area has increased ash content due to gasification of C and the ash composition is altered due to both reduction and gasification of ash minerals as e.g. SiO2 and alkalis in raceway and oxidation/condensation of gaseous compounds and uptake of compounds from the melt. Coke exposed to highest temperatures in the raceway area have increased the most in graphitization degree, and subsequent bird’s nest and deadman cokes graphitization degrees decreases. K2O-content in coke correlates to the graphitization degree as well as the SiO2/Al2O3 quotient which decreases at higher temperatures. Presence of slag and coke aggregates indicates the formation of bird’s nests at the end of the raceway. The end of raceway and position of a significant bird's nest in the industrial samples are indicated by the increasing content of K2O and increasing ratio of SiO2/Al2O3 in coke. In the industrial BF the pronounced formation of a bird’s nest redirect the gas from moving towards the BF center. As a result the coke in deadman cannot be heated and the temperature indicated by the graphitization degree decreases.Injection of BFD influences the raceway conditions as the combustion peak is moved further into the raceway when BFD and PC mix are injected. Analyze of fines shows remaining unreacted BFD, which contains iron oxide with oxidation degree between FeO and metallic Fe. Increased FeO-content in raceway will decrease the melting point of tuyere slag and therefore improve the permeability at raceway end and the fact that the core when drilled could be pushed further into the EBF than for the other cores indicates higher permeability after injection of PC and BFD mixture.

Place, publisher, year, edition, pages
Luleå: MEFOS, 2012
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-30073 (URN)3c588630-2c28-4001-9a14-ab525b841e32 (Local ID)978-91-637-0859-6 (ISBN)3c588630-2c28-4001-9a14-ab525b841e32 (Archive number)3c588630-2c28-4001-9a14-ab525b841e32 (OAI)
Conference
International Conference on Process Development in Iron and Steelmaking : 10/06/2012 - 13/06/2012
Note
Godkänd; 2012; 20120614 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Lundgren, M., Björkman, B., Leimalm, U. & Ökvist, L. S. (2011). Off-gas dust from experimental and production blast furnaces (ed.). In: (Ed.), (Ed.), Proceedings: METEC InSteelCon 2011 : Düsseldorf, Germany, CCD Congress Center Düsseldorf, 27th June - 1st July, 2011 ; it unites for international congresses/conferences under one roof: ECIC, 6th European Coke and Ironmaking Congress; ECCC, 7th European Continuous Casting Conference; EECRsteel, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry; STEELSIM, 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking. Paper presented at European Coke and Ironmaking Congress : 27/06/2011 - 01/07/2011. Düsseldorf
Open this publication in new window or tab >>Off-gas dust from experimental and production blast furnaces
2011 (English)In: Proceedings: METEC InSteelCon 2011 : Düsseldorf, Germany, CCD Congress Center Düsseldorf, 27th June - 1st July, 2011 ; it unites for international congresses/conferences under one roof: ECIC, 6th European Coke and Ironmaking Congress; ECCC, 7th European Continuous Casting Conference; EECRsteel, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry; STEELSIM, 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking, Düsseldorf, 2011Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Düsseldorf: , 2011
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-37357 (URN)b5b0e633-448a-46b2-84c4-272500b8814f (Local ID)b5b0e633-448a-46b2-84c4-272500b8814f (Archive number)b5b0e633-448a-46b2-84c4-272500b8814f (OAI)
Conference
European Coke and Ironmaking Congress : 27/06/2011 - 01/07/2011
Note
Godkänd; 2011; Bibliografisk uppgift: 1 DVD-ROM; 20111013 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Sundqvist, L., Lundgren, M., Wikström, J.-O. & Eklund, N. (2011). Raceway and hearth conditions relative process conditions in the LKAB experimental BF (ed.). In: (Ed.), (Ed.), Proceedings: METEC InSteelCon 2011 : Düsseldorf, Germany, CCD Congress Center Düsseldorf, 27th June - 1st July, 2011 ; it unites for international congresses/conferences under one roof: ECIC, 6th European Coke and Ironmaking Congress; ECCC, 7th European Continuous Casting Conference; EECRsteel, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry; STEELSIM, 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking. Paper presented at European Coke and Ironmaking Congress : 27/06/2011 - 01/07/2011. Düsseldorf
Open this publication in new window or tab >>Raceway and hearth conditions relative process conditions in the LKAB experimental BF
2011 (English)In: Proceedings: METEC InSteelCon 2011 : Düsseldorf, Germany, CCD Congress Center Düsseldorf, 27th June - 1st July, 2011 ; it unites for international congresses/conferences under one roof: ECIC, 6th European Coke and Ironmaking Congress; ECCC, 7th European Continuous Casting Conference; EECRsteel, 1st International Conference on Energy Efficiency and CO2 Reduction in the Steel Industry; STEELSIM, 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking, Düsseldorf, 2011Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Düsseldorf: , 2011
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-26939 (URN)03490065-4252-4108-af7e-8eeb177c6779 (Local ID)03490065-4252-4108-af7e-8eeb177c6779 (Archive number)03490065-4252-4108-af7e-8eeb177c6779 (OAI)
Conference
European Coke and Ironmaking Congress : 27/06/2011 - 01/07/2011
Note
Godkänd; 2011; Bibliografisk uppgift: 1 DVD-ROM; 20111212 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Lundgren, M. (2010). Blast furnace coke properties and the influence on off-gas dust (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Blast furnace coke properties and the influence on off-gas dust
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In blast furnace ironmaking, efforts are made to decrease the coke consumption mainly by increasing the pulverized coal injection rate. This will cause changes in in-furnace reduction conditions, burden distribution and demands on raw material strength, etc. In order to maintain stable operation and minimize material losses through the off-gas, it is important to understand fines generation and behaviour in the blast furnace. The strength and reactivity of coke at high temperature, measured by the Coke Strength after Reaction (CSR) and Coke Reactivity Index (CRI), have been studied. Mechanisms of disintegration were evaluated using basket samples charged into the LKAB Experimental Blast Furnace (EBF) prior to quenching and dissection. Coke charged into basket samples was analysed with CSR/CRI tests and compared with treated coke from the blast furnace. Results from tumbling tests, chemical analyses of coarse and fine material, as well as Light Optical Microscope (LOM) studies of original and treated coke have been combined and evaluated. The results indicate a correlation between the ash composition and CSR values. Differences in the texture of the coke were determined with LOM, and a change in the coke texture during the CSR/CRI test conditions was found. The results suggest that the main reaction between coke and CO2 during the solution loss reaction took place in isotropic areas, which was especially pronounced in coke with a low CSR. Signs of degradation were apparent throughout the coke pieces that have undergone CSR/CRI testing, but were less observable in coke reacted in the blast furnace. The results indicate that the solution loss reaction was generally limited by the chemical reaction rate in the CSR/CRI test, while in the blast furnace the reaction is limited by the diffusion rate. Coke degradation is therefore mostly restricted to the coke surface in the blast furnace. At a later EBF campaign, off-gas dust and shaft fines were sampled during operation with different iron-bearing materials. EBF process data were used to evaluate the relationship between off-gas dust amounts and furnace conditions. Characterization was focused on fines from coke, iron-bearing materials and slag formers. The graphitization degree (Lc value) of coke taken out of the EBF shaft and coke in flue dust was determined in order to trace the fines generation position. The results showed that flue dust, mainly <0.5 mm, was mechanically formed and created in the same manner for all investigated samples. Carbon-containing particles dominated in the fractions >0.075 mm and consisted mainly of coke particles originating from the shaft. Solution loss in the shaft had a negligible effect on coke degradation and the coke particles which ended up in the flue dust were mainly derived from abrasion at low temperatures. Sludge consisted mainly of chemically formed spherical particles <1μm formed in the blast furnace high-temperature area and then precipitated from the ascending gas as the temperature decreased. The amount of alkali and SiO2 in sludge increased with higher pulverized coal injection rates and flame temperatures, which confirmed that submicron spherical particles in sludge originated from the high-temperature area around the raceway. Theoretical critical particle diameters of materials, which could be blown out with the off-gas, were estimated. Flow conditions in the top of the shaft as well as the properties of fine particles in terms of size and density are important when outflow of mechanical dust, such as flue dust, is concerned. Low off-gas temperatures, and thus lower off-gas velocities, are desirable for blast furnace operation with low amounts of flue dust.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2010. p. 54
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-18007 (URN)65af0d60-5777-11df-a0f4-000ea68e967b (Local ID)978-91-7439-102-2 (ISBN)65af0d60-5777-11df-a0f4-000ea68e967b (Archive number)65af0d60-5777-11df-a0f4-000ea68e967b (OAI)
Note

Godkänd; 2010; 20100504 (lunmar); LICENTIATSEMINARIUM Ämnesområde: Processmetallurgi/Process Metallurgy Examinator: Professor Bo Björkman, Luleå tekniska universitet Diskutant: Docent Bo Lindblom, LKAB Tid: Tisdag den 8 juni 2010 kl 13.00 Plats: F531, Luleå tekniska universitet

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Leimalm, U., Lundgren, M., Ökvist, L. S. & Björkman, B. (2010). Off-gas dust in an experimental blast furnace: Part 1: Characterization of flue dust, sludge and shaft fines (ed.). Paper presented at . ISIJ International, 50(11), 1560-1569
Open this publication in new window or tab >>Off-gas dust in an experimental blast furnace: Part 1: Characterization of flue dust, sludge and shaft fines
2010 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 50, no 11, p. 1560-1569Article in journal (Refereed) Published
Abstract [en]

In blast furnace (BF) ironmaking, efforts are made to decrease coke consumption, which can be done by increasing the pulverized coal injection rate (PCR). This will cause changes in in-furnace reduction conditions, burden distribution, demands on raw material strength, etc. In order to maintain stable operation, but also to obtain low amounts of material losses through the off-gas, it is important to understand fines generation and behaviour in the BF. Off-gas dust and shaft fines generated in the LKAB Experimental Blast Furnace (EBF) were sampled during operation with olivine pellets and mixtures of acid pellets and sinter as iron-bearing materials. Characterization using XRD, SEM and LOM was focused on fines from iron-bearing materials, coke and slag formers. The results showed that flue dust, mainly <0.5 mm, was mechanically formed and created in the same manner for all investigated samples. Carbon-containing particles dominated in the fractions >0.075 mm and consisted mainly of coke particles from the shaft. Fe-containing particles, as Fe2O3 from the top of the shaft, formed the major part of flue dust fractions <0.063 mm. Particles from slag formers such as quartzite and limestone were observed in flue dust when slag formers were utilized in the feed. Sludge consisted mainly of chemically formed spherical particles <1 μm precipitated from the ascending gas as the temperature decreased.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-15035 (URN)e7e935a0-0819-11e0-b767-000ea68e967b (Local ID)e7e935a0-0819-11e0-b767-000ea68e967b (Archive number)e7e935a0-0819-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2010; 20101215 (lunmar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, M., Leimalm, U., Hyllander, G., Ökvist, L. S. & Björkman, B. (2010). Off-gas dust in an experimental blast furnace: Part 2: Relation to furnace conditions (ed.). Paper presented at . ISIJ International, 50(11), 1570-1580
Open this publication in new window or tab >>Off-gas dust in an experimental blast furnace: Part 2: Relation to furnace conditions
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2010 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 50, no 11, p. 1570-1580Article in journal (Refereed) Published
Abstract [en]

In the blast furnace process, material losses are caused by particles that are blown out of the furnace by the off-gas. In order to reduce these losses, it is important to understand the correlations between furnace conditions and off-gas dust formation. Off-gas dust, as flue dust and sludge, were collected during shaft probe sampling in LKAB Experimental Blast Furnace (EBF). Process data was used to evaluate the relationship between off-gas dust amounts and furnace conditions. The graphitization degree (Lc value) of shaft coke and coke in flue dust was determined using XRD measurements. Solution loss in the shaft had a negligible effect on coke degradation and the coke particles which ended up in the flue dust were mainly derived from abrasion at low temperatures. The amount of alkali and SiO2 in sludge increased with higher PCR and flame temperature, which confirmed that submicron spherical particles in sludge originated from the high temperature area around the raceway. Theoretical critical particle diameters of materials, which could be blown out with the off-gas, were estimated. Flow conditions in the top of the shaft as well as and the properties of fine particles in terms of size and density are important when outflow of mechanical dust, such as flue dust, is concerned. Low off-gas temperatures, and thus lower off-gas velocities, are favourable for low flue dust amounts expelled from the blast furnace.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-8650 (URN)10.2355/isijinternational.50.1570 (DOI)000284967700008 ()2-s2.0-79551606370 (Scopus ID)72b68110-081a-11e0-b767-000ea68e967b (Local ID)72b68110-081a-11e0-b767-000ea68e967b (Archive number)72b68110-081a-11e0-b767-000ea68e967b (OAI)
Note
Validerad; 2010; 20101215 (lunmar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lundgren, M., Ökvist, L. S. & Björkman, B. (2009). Coke reactivity under blast furnace conditions and in the CSR/CRI test (ed.). Steel Research International, 80(6), 396-401
Open this publication in new window or tab >>Coke reactivity under blast furnace conditions and in the CSR/CRI test
2009 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 80, no 6, p. 396-401Article in journal (Refereed) Published
Abstract [en]

The present work aims to study the high-temperature strength of coke. Mechanisms of disintegration were evaluated using basket samples charged into LKAB's experimental blast furnace prior to quenching and dissection. Coke charged into basket samples was analysed with CSR/CRI tests and compared with treated coke from the blast furnace. Results from tumbling tests, chemical analyses of coarse and fine material, as well as light optical microscopy studies of original and treated coke have been combined and evaluated. The results indicate a correlation between the ash composition and the CSR values. Differences in the texture of the coke were noted with light optical microscopy, and a significant change in the coke texture during the CSR/CRI test conditions was found. The results suggest that the main reaction between coke and CO2 took place in isotropic areas, which was especially pronounced in coke with a low CSR. Signs of degradation were apparent throughout the coke pieces that have undergone CSR/CRI testing, but were less observable in coke reacted in the blast furnace. The results indicate that reaction with CO2 is generally limited by the chemical reaction rate in the CSR/CRI test, while in the blast furnace the reaction is limited by the diffusion rate. Coke degradation is therefore mostly restricted to the coke surface in the blast furnace.

Keywords
Technology - Chemical engineering, Teknikvetenskap - Kemiteknik
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-14876 (URN)e4d8f4b0-7ab0-11de-9f57-000ea68e967b (Local ID)e4d8f4b0-7ab0-11de-9f57-000ea68e967b (Archive number)e4d8f4b0-7ab0-11de-9f57-000ea68e967b (OAI)
Note

Validerad; 2009; 20090727 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, M., Björkman, B. & Ökvist, L. S. (2008). Coke reactivity under blast furnace condition and in the CSR/CRI test (ed.). In: (Ed.), (Ed.), SCANMET III: 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden. Paper presented at International Conference on Process Development in Iron and Steelmaking : 08/06/2008 - 11/06/2008 (pp. 125-134). Luleå: MEFOS, 2
Open this publication in new window or tab >>Coke reactivity under blast furnace condition and in the CSR/CRI test
2008 (English)In: SCANMET III: 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden, Luleå: MEFOS , 2008, Vol. 2, p. 125-134Conference paper, Published paper (Refereed)
Abstract [en]

The present work aims to study the high-temperature strength of coke. Mechanisms of disintegration were evaluated using basket samples charged into LKAB's experimental blast furnace prior to quenching and dissection. Coke charged into basket samples were analysed with CSR/CRI tests and compared with treated coke from the blast furnace. Results from tumbling tests, chemical analyses of coarse and fine material, as well as light optical microscopy studies of original and treated coke have been combined and evaluated.The results indicate a correlation between the ash composition and the CSR values. Differences in the texture of the coke were noted with light optical microscopy, and a significant change in the coke texture during the CSR/CRI test conditions was found. The results suggest that the main reaction between coke and CO2 took place in isotropic areas, which was especially pronounced in coke with a low CSR. Signs of degradation were apparent throughout the coke pieces that have undergone CSR/CRI testing, but were less observable in coke reacted in the blast furnace. The results indicate that reaction with CO2 is generally limited by the chemical reaction rate in the CSR/CRI test, while in the blast furnace the reaction is limited by the diffusion rate. Coke degradation is therefore mostly restricted to the coke surface in the blast furnace.

Place, publisher, year, edition, pages
Luleå: MEFOS, 2008
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-36978 (URN)ad607510-704f-11dd-8151-000ea68e967b (Local ID)978-91-633-2270-9 (ISBN)ad607510-704f-11dd-8151-000ea68e967b (Archive number)ad607510-704f-11dd-8151-000ea68e967b (OAI)
Conference
International Conference on Process Development in Iron and Steelmaking : 08/06/2008 - 11/06/2008
Note
Godkänd; 2008; 20080822 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
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