The Experts below are selected from a list of 2292 Experts worldwide ranked by ideXlab platform
Veena Sahajwalla - One of the best experts on this subject based on the ideXlab platform.
-
the evolution of structural order microstructure and mineral matter of Metallurgical Coke in a blast furnace a review
Fuel, 2014Co-Authors: Kejiang Li, Veena Sahajwalla, Rita Khanna, Jianliang Zhang, Tianjun Yang, Dewen KongAbstract:Abstract The implementation of pulverized coal injection technology has resulted in the reduction in the amounts of Coke being used in the blast furnace, which has led to increased demands for high quality Cokes to provide enhanced performance. Under the twin pressures of resource shortage of coking coals and continuous requirements for improved Coke quality, an in-depth understanding of Coke behavior in blast furnace has become very important and pertinent. This review article is focused on a comprehensive investigation on the evolution of structural order, microstructure and mineral matter of Metallurgical Coke in a blast furnace and presents various mechanisms of Coke degradation during its descent in a blast furnace toward establishing reference standards for Coke quality and performance. Coke structure, microstructure and reactivity were investigated as a function of temperature, its location in the blast furnace and under the influence of alkalis above the tuyere level. The transformation of Coke in the blast furnace hearth and its dissolution into hot metal were also reviewed. The current indices for evaluating Coke quality were examined based on the modifications of Coke structure, and several unresolved issues in the field requiring further research were identified. This literature survey has shown that while crystalline order and microstructure had a strong influence on carburization, gasification reactions and the strength of Coke, factors such as mineral matter, alkalis, temperature were among some of the important factors that affected the degradation of Coke in a blast furnace.
-
Reduction of FeO in EAF steelmaking slag by blends of Metallurgical Coke and end-of-life polyethylene terephthalate
Ironmaking & Steelmaking, 2013Co-Authors: James Ransford Dankwah, Pramod Koshy, Veena SahajwallaAbstract:AbstractThe reduction of FeO containing slag by blends of Metallurgical Coke and end-of-life polyethylene terephthalate (PET) has been investigated through experiments conducted in a laboratory scale horizontal tube furnace. Composite pellets of EAF slag (47·1%FeO) with Coke, PET and blends of Coke/PET (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analysed for CH4, CO and CO2 using an online infrared gas analyser (IR). The extent of reduction after ten minutes, level of carburisation and desulphurisation were determined for each carbonaceous reductant. The results show significant improvement in extent of reduction, level of carburisation and desulphurisation of the reduced metal when Coke is blended with PET.
-
reduction of feo in eaf steelmaking slag by blends of Metallurgical Coke and end of life tyre
Steel Research International, 2012Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul Okane, Veena SahajwallaAbstract:The reduction of FeO-containing slag by blends of Metallurgical Coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with Coke, RT, and blends of Coke/RT (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analyzed for CO and CO2using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when Coke is blended with RT. Blending of Coke with RT resulted in a decrease in direct CO2 emissions from the reduction reactions.
-
Reduction of FeO in EAF Steelmaking Slag by Blends of Metallurgical Coke and End‐of‐Life Tyre
steel research international, 2012Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul O’kane, Veena SahajwallaAbstract:The reduction of FeO-containing slag by blends of Metallurgical Coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with Coke, RT, and blends of Coke/RT (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analyzed for CO and CO2using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when Coke is blended with RT. Blending of Coke with RT resulted in a decrease in direct CO2 emissions from the reduction reactions.
-
reduction of feo in eaf steelmaking slag by Metallurgical Coke and waste plastics blends
Isij International, 2011Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul Okane, Catherine Skidmore, David Knights, N Sahachaudhury, Veena SahajwallaAbstract:In Australia, the use of plastics has increased tremendously over the last few decades, but less than 20% of the waste plastics are recycled. The rest is usually landfilled, which poses major environmental problems. The solution to this problem involves the development of novel environmentally-benign technologies that would utilise these waste materials. This work investigates the reduction of EAF slags (47% FeO) by blends of Metallurgical Coke with High-Density Polyethylene (HDPE) plastics at 1550°C. The experiments were conducted in a laboratory-scale horizontal tube furnace, and were coupled with off-gas analysis using an infrared gas analyser and a multiple gas chromatographic analyser. The results indicate that the rate of FeO reduction in slags is significantly higher when the Coke/plastics blends were used compared to pure Coke, with the maximum rate of reduction (Blend 4) being over twice that of Coke. Moreover, the CO2 content in the off-gas was observed to decrease (by ~75%) with increase in the polymer content of the blend. Additionally, the degree of carburisation and the removal of sulphur from the metal improved considerably when the Coke was blended with plastics. The observed improvements in the rates of reduction, carburisation and desulphurisation are attributed to the reactions of hydrogen evolved from the waste plastics at these high temperatures.
Gerd Rantitsch - One of the best experts on this subject based on the ideXlab platform.
-
Assessing the quality of Metallurgical Coke by Raman spectroscopy
International Journal of Coal Geology, 2014Co-Authors: Gerd Rantitsch, Johannes Schenk, Anrin Bhattacharyya, Nils Keno LünsdorfAbstract:Abstract Metallurgical Coke should be resistant to mechanical, thermal, and chemical influences. This resistance is related to the structural order of the organic constituents. Raman microspectroscopy of carbonaceous matter (RSCM) is demonstrated as a promising tool to investigate this property. Variations of the microstructure among samples with different quality parameters are detected by analyzing the Raman spectra collected on their individual Coke lumps. Three basic types of Raman spectra are discriminated. Their predominance in a bulk sample predicts roughly the Coke quality, estimated by an ISO standardized test. To investigate the structural behavior of Coke in a blast furnace, several samples have been treated under typical gas atmospheres of the blast furnace process (carbon dioxide, nitrogen) at temperatures between 850 °C and 1100 °C for 120 min. RSCM data measured on the treated lumps evidence a progressive transformation of poorly ordered organic microstructure towards a higher structural order.
-
Structural Characterization of Metallurgical Coke by Raman Spectroscopy
BHM Berg- und Hüttenmännische Monatshefte, 2013Co-Authors: Gerd Rantitsch, Johannes Schenk, Keno Lünsdorf, Anrin Bhattacharyya, Martina Hanel, Daniela Wallner, Heidi KaltenböckAbstract:To investigate the factors influencing the structural order of Metallurgical Coke, several Coke samples were treated by temperatures between 850 °C and 1300 °C and analyzed by Raman Spectroscopy. A quantitative Raman-parameter is proposed to reflect the structural state of a Coke sample. Zur Untersuchung der Faktoren, die die strukturelle Prägung von Hochofen Koks beeinflussen, wurden Koks-Proben mit Stickstoff und Kohlendioxid bei verschiedenen Temperaturen (850 °C bis 1300 °C) für 60 und 120 min behandelt und durch die Anwendung der Raman Spektroskopie mikrostrukturell charakterisiert. Zur strukturellen Bewertung einer Koks-Probe wird ein quantitativer Raman-Parameter vorgeschlagen.
-
Structural Characterization of Metallurgical Coke by Raman Spectroscopy
BHM Berg- und Hüttenmännische Monatshefte, 2013Co-Authors: Gerd Rantitsch, Johannes Schenk, Keno Lünsdorf, Anrin Bhattacharyya, Martina Hanel, Daniela Wallner, Heidi KaltenböckAbstract:To investigate the factors influencing the structural order of Metallurgical Coke, several Coke samples were treated by temperatures between 850 °C and 1300 °C and analyzed by Raman Spectroscopy. A quantitative Raman-parameter is proposed to reflect the structural state of a Coke sample.
David Knights - One of the best experts on this subject based on the ideXlab platform.
-
reduction of feo in eaf steelmaking slag by Metallurgical Coke and waste plastics blends
Isij International, 2011Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul Okane, Catherine Skidmore, David Knights, N Sahachaudhury, Veena SahajwallaAbstract:In Australia, the use of plastics has increased tremendously over the last few decades, but less than 20% of the waste plastics are recycled. The rest is usually landfilled, which poses major environmental problems. The solution to this problem involves the development of novel environmentally-benign technologies that would utilise these waste materials. This work investigates the reduction of EAF slags (47% FeO) by blends of Metallurgical Coke with High-Density Polyethylene (HDPE) plastics at 1550°C. The experiments were conducted in a laboratory-scale horizontal tube furnace, and were coupled with off-gas analysis using an infrared gas analyser and a multiple gas chromatographic analyser. The results indicate that the rate of FeO reduction in slags is significantly higher when the Coke/plastics blends were used compared to pure Coke, with the maximum rate of reduction (Blend 4) being over twice that of Coke. Moreover, the CO2 content in the off-gas was observed to decrease (by ~75%) with increase in the polymer content of the blend. Additionally, the degree of carburisation and the removal of sulphur from the metal improved considerably when the Coke was blended with plastics. The observed improvements in the rates of reduction, carburisation and desulphurisation are attributed to the reactions of hydrogen evolved from the waste plastics at these high temperatures.
-
recycling waste plastics in eaf steelmaking carbon slag interactions of hdpe Coke blends
Steel Research International, 2009Co-Authors: Veena Sahajwalla, Paul Okane, Rita Khanna, Catherine Skidmore, N Sahachaudhury, Muhammad Faz Rahman, David KnightsAbstract:Due to the inherent limitations of current methods of plastic waste disposal, there have been concerted efforts worldwide towards developing alternative, environment friendly and economic recycling processes. With an aim to recycle waste plastics in EAF steelmaking, carbon/slag interactions for a number of blends made of Metallurgical Coke and HDPE (high density polyethylene) and an EAF slag (34.8 mass-% Fe2O3) have been investigated at 1550°C using a sessile drop arrangement. The rate of gas generation showed an increase with increasing HDPE concentration, reaching a maximum for blend #3 (with appr. 30 % HDPE) and decreasing thereafter. Among all the blends investigated, blend #3 showed significantly higher levels of slag foaming as compared to Metallurgical Coke. HDPE-Coke blends also showed better wetting compared to Metallurgical Coke with contact angles in some cases improving from 140° to 70° after 10 minutes of contact. These results have been discussed in terms of ash and sulphur contents of carbonaceous residues and dynamic changes in slag composition. Industrial trials on blend #3 showed a good agreement with laboratory results. This work opens novel avenues for the utilisation of plastics wastes as a valuable carbon resource in EAF steelmaking.
-
Recycling of rubber tires in electric arc furnace steelmaking: simultaneous combustion of Metallurgical Coke and rubber tyres blends
Energy & Fuels, 2009Co-Authors: Magdalena Zaharia, Veena Sahajwalla, Paul O’kane, Byong-chul Kim, Rita Khanna, N. Saha-chaudhury, Jonathan Dicker, Catherine Skidmore, David KnightsAbstract:The present study investigates the effect of addition of waste rubber tires on the combustion behavior of its blends with Coke for carbon injection in electric arc furnace steelmaking. Waste rubber tires were mixed in different proportions with Metallurgical Coke (MC) (10:90, 20:80, 30:70) for combustion and pyrolysis at 1473 K in a drop tube furnace (DTF) and thermogravimetric analyzer (TGA), respectively. Under experimental conditions most of the rubber blends indicated higher combustion efficiencies compared to those of the constituent Coke. In the early stage of combustion the weight loss rate of the blends is much faster compared to that of the raw Coke due to the higher volatile yield of rubber. The presence of rubber in the blends may have had an impact upon the structure during the release and combustion of their high volatile matter (VM) and hence increased char burnout. Measurements of micropore surface area and bulk density of the chars collected after combustion support the higher combustion e...
Rita Khanna - One of the best experts on this subject based on the ideXlab platform.
-
the evolution of structural order microstructure and mineral matter of Metallurgical Coke in a blast furnace a review
Fuel, 2014Co-Authors: Kejiang Li, Veena Sahajwalla, Rita Khanna, Jianliang Zhang, Tianjun Yang, Dewen KongAbstract:Abstract The implementation of pulverized coal injection technology has resulted in the reduction in the amounts of Coke being used in the blast furnace, which has led to increased demands for high quality Cokes to provide enhanced performance. Under the twin pressures of resource shortage of coking coals and continuous requirements for improved Coke quality, an in-depth understanding of Coke behavior in blast furnace has become very important and pertinent. This review article is focused on a comprehensive investigation on the evolution of structural order, microstructure and mineral matter of Metallurgical Coke in a blast furnace and presents various mechanisms of Coke degradation during its descent in a blast furnace toward establishing reference standards for Coke quality and performance. Coke structure, microstructure and reactivity were investigated as a function of temperature, its location in the blast furnace and under the influence of alkalis above the tuyere level. The transformation of Coke in the blast furnace hearth and its dissolution into hot metal were also reviewed. The current indices for evaluating Coke quality were examined based on the modifications of Coke structure, and several unresolved issues in the field requiring further research were identified. This literature survey has shown that while crystalline order and microstructure had a strong influence on carburization, gasification reactions and the strength of Coke, factors such as mineral matter, alkalis, temperature were among some of the important factors that affected the degradation of Coke in a blast furnace.
-
recycling plastics as a resource for electric arc furnace eaf steelmaking combustion and structural transformations of Metallurgical Coke and plastic blends
Energy & Fuels, 2010Co-Authors: Veena Sahajwalla, Magdalena Zaharia, Rita Khanna, N Sahachaudhury, Somyote Kongkarat, Paul OkaneAbstract:Recycling end of life products, such as waste tires and waste plastics in iron- and steelmaking permits their use as energy and material resources. The current paper discusses the combustion efficiencies of blends of Metallurgical Coke (MC) with plastics for electric arc furnace (EAF) steelmaking. Laboratory tests involved the combustion in a drop tube furnace (DTF) at 1473 K of MC premixed with different proportions of plastics, polypropylene (PP), and high-density polyethylene (HDPE) (10−30%) under a 20% O2 and 80% N2 gas mixture. In the tested conditions, Coke−plastic blends indicated higher combustion efficiencies compared to Coke. The gas-phase reactions appear to be influenced by the amount of volatile matter present in the carbonaceous matrix and its subsequent effect on the structural transformation of the particles because of the release of volatiles. The surface area of the Coke−polymeric mixtures before and after combustion was found to be higher than the surface area of Coke alone. The residua...
-
recycling waste plastics in eaf steelmaking carbon slag interactions of hdpe Coke blends
Steel Research International, 2009Co-Authors: Veena Sahajwalla, Paul Okane, Rita Khanna, Catherine Skidmore, N Sahachaudhury, Muhammad Faz Rahman, David KnightsAbstract:Due to the inherent limitations of current methods of plastic waste disposal, there have been concerted efforts worldwide towards developing alternative, environment friendly and economic recycling processes. With an aim to recycle waste plastics in EAF steelmaking, carbon/slag interactions for a number of blends made of Metallurgical Coke and HDPE (high density polyethylene) and an EAF slag (34.8 mass-% Fe2O3) have been investigated at 1550°C using a sessile drop arrangement. The rate of gas generation showed an increase with increasing HDPE concentration, reaching a maximum for blend #3 (with appr. 30 % HDPE) and decreasing thereafter. Among all the blends investigated, blend #3 showed significantly higher levels of slag foaming as compared to Metallurgical Coke. HDPE-Coke blends also showed better wetting compared to Metallurgical Coke with contact angles in some cases improving from 140° to 70° after 10 minutes of contact. These results have been discussed in terms of ash and sulphur contents of carbonaceous residues and dynamic changes in slag composition. Industrial trials on blend #3 showed a good agreement with laboratory results. This work opens novel avenues for the utilisation of plastics wastes as a valuable carbon resource in EAF steelmaking.
-
Recycling of rubber tires in electric arc furnace steelmaking: simultaneous combustion of Metallurgical Coke and rubber tyres blends
Energy & Fuels, 2009Co-Authors: Magdalena Zaharia, Veena Sahajwalla, Paul O’kane, Byong-chul Kim, Rita Khanna, N. Saha-chaudhury, Jonathan Dicker, Catherine Skidmore, David KnightsAbstract:The present study investigates the effect of addition of waste rubber tires on the combustion behavior of its blends with Coke for carbon injection in electric arc furnace steelmaking. Waste rubber tires were mixed in different proportions with Metallurgical Coke (MC) (10:90, 20:80, 30:70) for combustion and pyrolysis at 1473 K in a drop tube furnace (DTF) and thermogravimetric analyzer (TGA), respectively. Under experimental conditions most of the rubber blends indicated higher combustion efficiencies compared to those of the constituent Coke. In the early stage of combustion the weight loss rate of the blends is much faster compared to that of the raw Coke due to the higher volatile yield of rubber. The presence of rubber in the blends may have had an impact upon the structure during the release and combustion of their high volatile matter (VM) and hence increased char burnout. Measurements of micropore surface area and bulk density of the chars collected after combustion support the higher combustion e...
Paul Okane - One of the best experts on this subject based on the ideXlab platform.
-
reduction of feo in eaf steelmaking slag by blends of Metallurgical Coke and end of life tyre
Steel Research International, 2012Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul Okane, Veena SahajwallaAbstract:The reduction of FeO-containing slag by blends of Metallurgical Coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with Coke, RT, and blends of Coke/RT (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analyzed for CO and CO2using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when Coke is blended with RT. Blending of Coke with RT resulted in a decrease in direct CO2 emissions from the reduction reactions.
-
reduction of feo in eaf steelmaking slag by Metallurgical Coke and waste plastics blends
Isij International, 2011Co-Authors: James Ransford Dankwah, Pramod Koshy, Paul Okane, Catherine Skidmore, David Knights, N Sahachaudhury, Veena SahajwallaAbstract:In Australia, the use of plastics has increased tremendously over the last few decades, but less than 20% of the waste plastics are recycled. The rest is usually landfilled, which poses major environmental problems. The solution to this problem involves the development of novel environmentally-benign technologies that would utilise these waste materials. This work investigates the reduction of EAF slags (47% FeO) by blends of Metallurgical Coke with High-Density Polyethylene (HDPE) plastics at 1550°C. The experiments were conducted in a laboratory-scale horizontal tube furnace, and were coupled with off-gas analysis using an infrared gas analyser and a multiple gas chromatographic analyser. The results indicate that the rate of FeO reduction in slags is significantly higher when the Coke/plastics blends were used compared to pure Coke, with the maximum rate of reduction (Blend 4) being over twice that of Coke. Moreover, the CO2 content in the off-gas was observed to decrease (by ~75%) with increase in the polymer content of the blend. Additionally, the degree of carburisation and the removal of sulphur from the metal improved considerably when the Coke was blended with plastics. The observed improvements in the rates of reduction, carburisation and desulphurisation are attributed to the reactions of hydrogen evolved from the waste plastics at these high temperatures.
-
recycling plastics as a resource for electric arc furnace eaf steelmaking combustion and structural transformations of Metallurgical Coke and plastic blends
Energy & Fuels, 2010Co-Authors: Veena Sahajwalla, Magdalena Zaharia, Rita Khanna, N Sahachaudhury, Somyote Kongkarat, Paul OkaneAbstract:Recycling end of life products, such as waste tires and waste plastics in iron- and steelmaking permits their use as energy and material resources. The current paper discusses the combustion efficiencies of blends of Metallurgical Coke (MC) with plastics for electric arc furnace (EAF) steelmaking. Laboratory tests involved the combustion in a drop tube furnace (DTF) at 1473 K of MC premixed with different proportions of plastics, polypropylene (PP), and high-density polyethylene (HDPE) (10−30%) under a 20% O2 and 80% N2 gas mixture. In the tested conditions, Coke−plastic blends indicated higher combustion efficiencies compared to Coke. The gas-phase reactions appear to be influenced by the amount of volatile matter present in the carbonaceous matrix and its subsequent effect on the structural transformation of the particles because of the release of volatiles. The surface area of the Coke−polymeric mixtures before and after combustion was found to be higher than the surface area of Coke alone. The residua...
-
recycling waste plastics in eaf steelmaking carbon slag interactions of hdpe Coke blends
Steel Research International, 2009Co-Authors: Veena Sahajwalla, Paul Okane, Rita Khanna, Catherine Skidmore, N Sahachaudhury, Muhammad Faz Rahman, David KnightsAbstract:Due to the inherent limitations of current methods of plastic waste disposal, there have been concerted efforts worldwide towards developing alternative, environment friendly and economic recycling processes. With an aim to recycle waste plastics in EAF steelmaking, carbon/slag interactions for a number of blends made of Metallurgical Coke and HDPE (high density polyethylene) and an EAF slag (34.8 mass-% Fe2O3) have been investigated at 1550°C using a sessile drop arrangement. The rate of gas generation showed an increase with increasing HDPE concentration, reaching a maximum for blend #3 (with appr. 30 % HDPE) and decreasing thereafter. Among all the blends investigated, blend #3 showed significantly higher levels of slag foaming as compared to Metallurgical Coke. HDPE-Coke blends also showed better wetting compared to Metallurgical Coke with contact angles in some cases improving from 140° to 70° after 10 minutes of contact. These results have been discussed in terms of ash and sulphur contents of carbonaceous residues and dynamic changes in slag composition. Industrial trials on blend #3 showed a good agreement with laboratory results. This work opens novel avenues for the utilisation of plastics wastes as a valuable carbon resource in EAF steelmaking.