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Papers by sheila devasahayam
SpringerBriefs in Earth Sciences, 2015
This chapter is about mineral processing of the rare earths (making the mined ore into a concentr... more This chapter is about mineral processing of the rare earths (making the mined ore into a concentrate of the valuable minerals), and extractive metallurgy of the rare earths (how to get the metals out of the concentrate). The mineral processing of three well-known exploited ore deposits is discussed in more detail.
CRC Press eBooks, Sep 15, 2016
Sustainable Materials and Technologies, Sep 1, 2018
A novel ambient condition production of superior strength, non-abrasive, non-sticky iron ore pell... more A novel ambient condition production of superior strength, non-abrasive, non-sticky iron ore pellets devoid of undesirable fines under the compression stress of 4 kN is presented. Interfacial bond between epoxy and iron oxide imparts high strength as opposed to physical bond in the conventional pellets. The pellets show high compression strength of 4 kN, without heat treatment compared to the industry requirement (2.5 kN) of an indurated pellet processed at 1200-1350 °C. Pelletization and iron ore reduction are accompanied by great reduction in energy and carbon dioxide emission. Enhanced rate and degree of iron ore reduction are due to secondary reactions involving carbon dioxide and the volatiles. Pellets reduced at 1550 °C show carbon dissolution up to 4 wt %, high porosity, low sulphur and slag levels. Silica fillers in the resin impart high mechanical strength to the crosslinked epoxy-iron oxide network facilitating mass transfer of the off-gases at the interface enhancing the reduction rate and the degree of reduction. Utilising biorenewable or recycled resin, will make this process sustainable, cleaner and cost-effective reducing the landfill burden.
Elsevier eBooks, 2013
Abstract: A number of coal parameters are used in coal selection for metallurgical applications. ... more Abstract: A number of coal parameters are used in coal selection for metallurgical applications. This chapter focuses mainly on coal parameters for use in coke-making and pulverised coal injection for the integrated iron and steel-making process. Parameters for use in alternative iron-making processes such as Corex® and other coal-based smelting reduction technologies are also discussed. This chapter reviews the current status of recent scientific advances in the area to better understand these parameters and thus efficiently utilise coal for various metallurgical applications. Where possible, the international standards related to the critical utilisation parameters identified are listed and discussed.
Polymers
This article reports the characterisation of pyrolysis of automotive shredder residue using in si... more This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, thermal analyses suggested one- to two-stage pyrolysis. Transformations in the first stage, at lower temperatures, were attributed to the degradation of carbonyl, hydroxyl, or carboxyl functional stabilisers (aldehyde and ether impurities, additives, and stabilisers in the ASR). The second stage transformations, at higher temperatures, were attributed to the thermal degradation of the polymer char. Simultaneous thermal analyses and gas-phase IR spectroscopy confirmed the evolution of the gases (alkanes (CH4), CO2, and moisture). The synchrotron IR data have demonstrated that a high heating rate (such as 150 °C/min) results in an incomplete conversion of ASRs unless sufficient time is provided. T...
Mining, Metallurgy & Exploration, 2007
Acid production or acid drainage is a major environmental issue that also has negative implicatio... more Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized py rite/acid production with depth in black coalmine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.
CRC Press eBooks, Aug 12, 2022
Sustainability in the Mineral and Energy Sectors, 2016
The mining industry has long sought a step change in productivity by integrating operations from ... more The mining industry has long sought a step change in productivity by integrating operations from mine to market. While there have been some success stories, in general the promise has not been delivered due to some crucial gaps in technology and systems. Many of those gaps have now been closed, or at least recognized, meaning the tools are now available to deliver the benefits of integration. THE MINING PRODUCTIVITY CHALLENGE The minerals industry faces a productivity and investment crisis. The "Millennium Super Cycle" from 2003 to 2011 was an unprecedented period of growth and investment. Throughput was increased and lower grade resources were developed to meet demand. The urgency to bring production to market quickly stretched people, project, and management resources. But the "boom" ended and prices have declined, with the industry left with a legacy of high costs, declining ore quality, and less efficient operating practices. Step changes to practice and productivity are needed to sustainably produce the minerals society needs. Groups including the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) are working with the global resources industries to reverse the trend of declining feed grade and quality through novel approaches and innovative solutions (Figures 3.1 and 3.2).
Polymers
Over 100 million tonnes of waste plastics is projected to enter our environment by 2030 [...]
Advances in Polymer Materials and Technology, 2016
Polymers, 2022
The author wishes to make the following correction to the above paper [...]
Sustainability in the Mineral and Energy Sectors, 2016
Sustainability in the Mineral and Energy Sectors, 2016
International Journal of Mineral Processing, 2015
Fly ash from coal power stations consists typically of a series of oxide minerals. These minerals... more Fly ash from coal power stations consists typically of a series of oxide minerals. These minerals can have beneficial effects when used as reinforcement in a plastic matrix. In this work the advanced technique SIMS has been utilised to identify the spatial distribution of the various minerals in fly ash in an epoxy matrix with fly ash weights of 10% and 50%. It is observed that SIMS, which can scan normally to a precision of 0.5 to 0.05 wt.%, could positively identify the distribution of the fly ash mineral elements in the epoxy. Attempts were also made to identify the fly ash element distribution in the epoxy using a composition analysis method, namely, EDS. However, it is observed that in the present fly ash-epoxy composites, EDS could not identify the fly ash elements demonstrating SIMS is a much preferred identification technique than the popular EDS method.
SpringerBriefs in Earth Sciences, 2015
This chapter is about mineral processing of the rare earths (making the mined ore into a concentr... more This chapter is about mineral processing of the rare earths (making the mined ore into a concentrate of the valuable minerals), and extractive metallurgy of the rare earths (how to get the metals out of the concentrate). The mineral processing of three well-known exploited ore deposits is discussed in more detail.
CRC Press eBooks, Sep 15, 2016
Sustainable Materials and Technologies, Sep 1, 2018
A novel ambient condition production of superior strength, non-abrasive, non-sticky iron ore pell... more A novel ambient condition production of superior strength, non-abrasive, non-sticky iron ore pellets devoid of undesirable fines under the compression stress of 4 kN is presented. Interfacial bond between epoxy and iron oxide imparts high strength as opposed to physical bond in the conventional pellets. The pellets show high compression strength of 4 kN, without heat treatment compared to the industry requirement (2.5 kN) of an indurated pellet processed at 1200-1350 °C. Pelletization and iron ore reduction are accompanied by great reduction in energy and carbon dioxide emission. Enhanced rate and degree of iron ore reduction are due to secondary reactions involving carbon dioxide and the volatiles. Pellets reduced at 1550 °C show carbon dissolution up to 4 wt %, high porosity, low sulphur and slag levels. Silica fillers in the resin impart high mechanical strength to the crosslinked epoxy-iron oxide network facilitating mass transfer of the off-gases at the interface enhancing the reduction rate and the degree of reduction. Utilising biorenewable or recycled resin, will make this process sustainable, cleaner and cost-effective reducing the landfill burden.
Elsevier eBooks, 2013
Abstract: A number of coal parameters are used in coal selection for metallurgical applications. ... more Abstract: A number of coal parameters are used in coal selection for metallurgical applications. This chapter focuses mainly on coal parameters for use in coke-making and pulverised coal injection for the integrated iron and steel-making process. Parameters for use in alternative iron-making processes such as Corex® and other coal-based smelting reduction technologies are also discussed. This chapter reviews the current status of recent scientific advances in the area to better understand these parameters and thus efficiently utilise coal for various metallurgical applications. Where possible, the international standards related to the critical utilisation parameters identified are listed and discussed.
Polymers
This article reports the characterisation of pyrolysis of automotive shredder residue using in si... more This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, thermal analyses suggested one- to two-stage pyrolysis. Transformations in the first stage, at lower temperatures, were attributed to the degradation of carbonyl, hydroxyl, or carboxyl functional stabilisers (aldehyde and ether impurities, additives, and stabilisers in the ASR). The second stage transformations, at higher temperatures, were attributed to the thermal degradation of the polymer char. Simultaneous thermal analyses and gas-phase IR spectroscopy confirmed the evolution of the gases (alkanes (CH4), CO2, and moisture). The synchrotron IR data have demonstrated that a high heating rate (such as 150 °C/min) results in an incomplete conversion of ASRs unless sufficient time is provided. T...
Mining, Metallurgy & Exploration, 2007
Acid production or acid drainage is a major environmental issue that also has negative implicatio... more Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized py rite/acid production with depth in black coalmine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.
CRC Press eBooks, Aug 12, 2022
Sustainability in the Mineral and Energy Sectors, 2016
The mining industry has long sought a step change in productivity by integrating operations from ... more The mining industry has long sought a step change in productivity by integrating operations from mine to market. While there have been some success stories, in general the promise has not been delivered due to some crucial gaps in technology and systems. Many of those gaps have now been closed, or at least recognized, meaning the tools are now available to deliver the benefits of integration. THE MINING PRODUCTIVITY CHALLENGE The minerals industry faces a productivity and investment crisis. The "Millennium Super Cycle" from 2003 to 2011 was an unprecedented period of growth and investment. Throughput was increased and lower grade resources were developed to meet demand. The urgency to bring production to market quickly stretched people, project, and management resources. But the "boom" ended and prices have declined, with the industry left with a legacy of high costs, declining ore quality, and less efficient operating practices. Step changes to practice and productivity are needed to sustainably produce the minerals society needs. Groups including the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) are working with the global resources industries to reverse the trend of declining feed grade and quality through novel approaches and innovative solutions (Figures 3.1 and 3.2).
Polymers
Over 100 million tonnes of waste plastics is projected to enter our environment by 2030 [...]
Advances in Polymer Materials and Technology, 2016
Polymers, 2022
The author wishes to make the following correction to the above paper [...]
Sustainability in the Mineral and Energy Sectors, 2016
Sustainability in the Mineral and Energy Sectors, 2016
International Journal of Mineral Processing, 2015
Fly ash from coal power stations consists typically of a series of oxide minerals. These minerals... more Fly ash from coal power stations consists typically of a series of oxide minerals. These minerals can have beneficial effects when used as reinforcement in a plastic matrix. In this work the advanced technique SIMS has been utilised to identify the spatial distribution of the various minerals in fly ash in an epoxy matrix with fly ash weights of 10% and 50%. It is observed that SIMS, which can scan normally to a precision of 0.5 to 0.05 wt.%, could positively identify the distribution of the fly ash mineral elements in the epoxy. Attempts were also made to identify the fly ash element distribution in the epoxy using a composition analysis method, namely, EDS. However, it is observed that in the present fly ash-epoxy composites, EDS could not identify the fly ash elements demonstrating SIMS is a much preferred identification technique than the popular EDS method.