The Experts below are selected from a list of 2331 Experts worldwide ranked by ideXlab platform
Merrick R Mahoney - One of the best experts on this subject based on the ideXlab platform.
-
uniaxial compression of metallurgical Coke samples with progressive loading
Fuel, 2018Co-Authors: David R Jenkins, Hannah Lomas, Merrick R MahoneyAbstract:Abstract Coke samples, produced from coals having a range of rank and vitrinite content, were subjected to uniaxial loading in a universal tester. Cokes were also imaged at high resolution using micro-CT. The aim was to understand the relationship between the internal microstructure of the Coke and Coke Strength under load. The loading was done in two separate ways, being either compression to failure or progressive loading. The results showed that the Coke samples underwent a form of stiffening at low loads, potentially due to closing of fine-scale pores and/or re-alignment of graphitic layers in the RMDC. Measurements of plastic strain indicated that these changes were permanent. At higher loads, small load-bearing components of the microstructure were found to break, leading to a softening of the Coke samples. Evidence of the breaking was observed using micro-CT images before and after loading of samples. The work has relevance to the understanding of the fundamentals of Coke Strength, as well as to issues relating to handling and preparation of Coke for standard testing.
-
Fractographic approach to metallurgical Coke failure analysis. Part 1: Cokes of single coal origin
Fuel, 2016Co-Authors: Richard Roest, Kim Hockings, Merrick R MahoneyAbstract:Abstract Metallurgical Coke is a complex brittle heterogeneous material consisting of carbon derived from fusible, semi-fusible and inert coal particles that forms a porous composite matrix. This paper presents a novel approach to assess and quantify the breakage behaviour and microstructural weaknesses in a pilot oven metallurgical Coke. The approach uses fractography, a method commonly applied to determine the fracture behaviour and origin(s) in homogeneous materials, such as metals and ceramics. Determination of the fracture origin(s), paths of crack propagation and microstructural weaknesses in such a complex heterogeneous material as metallurgical Coke represents a significant advance in both the application of fractography and the assessment of Coke Strength and breakage behaviour. Identification of the key features that contribute to the Coke’s failure will facilitate better prediction of Coke Strength from coal properties and ultimately optimisation of the coal blending process. Key features and markings have been clearly identified on fracture surfaces that can either be traced back to the fracture origin or give an indication of the type of fracture or stresses to which the Coke has been subjected, including the directionality and Strength of those stresses. These markings include hackle, hackle twist and wallner lines, as well as markings generated by conchoidal and overload fractures. A three-step approach was applied to determine the breakage behaviour in stabilized lumps of the pilot oven Coke, in which fractured Coke surfaces were analysed at the macro, micro and submicron levels. The observed mechanisms of failure were quantified and summarised using a radar diagram.
-
development of a metallurgical Coke analogue to investigate the effects of Coke mineralogy on Coke reactivity
2012Co-Authors: Raymond J Longbottom, Brian J Monaghan, Oliver Nelson Scholes, Merrick R MahoneyAbstract:In this study the suitability of a laboratory analogue for Coke for studying the effects of minerals on the reactivity of Coke was evaluated. In addition to this, the effects of different physical properties and production conditions on the reactivity of the Coke analogue were also tested. The Coke analogue was used for control testing of specific mineral, and to some degree maceral, effects on reactivity. Such information would improve our fundamental understanding of Coke reactivity behaviour and could be used to develop more accurate predictive models of Coke Strength after reaction (CSR) or associated indices and Coke properties. The effect on reactivity of the addition of different simple minerals to the Coke analogue was evaluated by conducting pseudo-Coke reactivity index (CRI) tests. It was found that the addition of minerals to the Coke analogue had an effect on its reactivity. While the addition of minerals also affected physical properties such as porosity, it was found that the minerals themselves played a role in determining the reactivity of the Coke analogue. The principal conclusion of this study though is that the Coke analogue has been identified as having potential to be a suitable tool for studying the effects of mineralogy on Coke reactivity in a CSR/CRI like test.
-
fissure formation in Coke 2 effect of heating rate shrinkage and Coke Strength
Fuel, 2010Co-Authors: D R Jenkins, Merrick R MahoneyAbstract:We investigate the effects of the heating rate, Coke shrinkage and Coke breakage Strength upon the fissure pattern developed in a Coke oven charge during carbonisation. This is done principally using a mechanistic model of the formation of fissures, which considers them to be an array of equally spaced fissures, whose depth follows a “period doubling” pattern based upon the time history of the fissures. The model results are compared with pilot scale Coke oven experiments. The results show that the effect of heating rate on the fissure pattern is different to the effect of Coke shrinkage, while the effect of Coke breakage Strength on the pattern is less pronounced. The results can be seen in both the shape and size of resulting Coke lumps after stabilisation. The approach gives the opportunity to consider means of controlling the carbonisation process in order to tune the size of the Coke lumps produced.
Richard Roest - One of the best experts on this subject based on the ideXlab platform.
-
Fractographic approach to metallurgical Coke failure analysis. Part 1: Cokes of single coal origin
Fuel, 2016Co-Authors: Richard Roest, Kim Hockings, Merrick R MahoneyAbstract:Abstract Metallurgical Coke is a complex brittle heterogeneous material consisting of carbon derived from fusible, semi-fusible and inert coal particles that forms a porous composite matrix. This paper presents a novel approach to assess and quantify the breakage behaviour and microstructural weaknesses in a pilot oven metallurgical Coke. The approach uses fractography, a method commonly applied to determine the fracture behaviour and origin(s) in homogeneous materials, such as metals and ceramics. Determination of the fracture origin(s), paths of crack propagation and microstructural weaknesses in such a complex heterogeneous material as metallurgical Coke represents a significant advance in both the application of fractography and the assessment of Coke Strength and breakage behaviour. Identification of the key features that contribute to the Coke’s failure will facilitate better prediction of Coke Strength from coal properties and ultimately optimisation of the coal blending process. Key features and markings have been clearly identified on fracture surfaces that can either be traced back to the fracture origin or give an indication of the type of fracture or stresses to which the Coke has been subjected, including the directionality and Strength of those stresses. These markings include hackle, hackle twist and wallner lines, as well as markings generated by conchoidal and overload fractures. A three-step approach was applied to determine the breakage behaviour in stabilized lumps of the pilot oven Coke, in which fractured Coke surfaces were analysed at the macro, micro and submicron levels. The observed mechanisms of failure were quantified and summarised using a radar diagram.
-
Fractographic approach to metallurgical Coke failure analysis. Part 2: Cokes from binary coal blends
Fuel, 2016Co-Authors: Richard RoestAbstract:Abstract Metallurgical Coke used in blast furnaces is the result of blending coals to achieve the optimum Coke Strength properties. Prediction of Coke Strength from coal properties relies primarily on statistical methods. Improvement of these models is desirable. We believe a better understanding of the fundamental factors controlling Coke Strength is required to achieve this. In this second of a series of three papers, we apply our recently developed fractographic approach to examine and quantify the breakage behaviour and microstructural weaknesses in pilot oven metallurgical Cokes from two series of single coals and binary blends of the coals. We have successfully applied fractography to perform an effective failure analysis of the complex, heterogeneous Coke material. Summaries of the factors contributing to the failure of each Coke studied have been presented as radar graphs. These graphs demonstrate that the failure profile of the Cokes from blends is not simply a weighted average of the fracture behaviour of the Cokes from the constituent single coals. Instead, non-additive effects are observed, and this may have implications for the mathematical models widely used to predict Coke behaviour and Strength in the blast furnace. Trends between the various fractographic parameters have been identified, and preliminary relation of these to both the maximum compressive Strength of each Coke and basic properties of the original coals, has been completed. Enhanced understanding of how the fracture behaviour of each Coke relates to the properties of the coal blend used will help facilitate better prediction of Coke Strength from coal properties and ultimately optimisation of the coal blending process.
Kim Hockings - One of the best experts on this subject based on the ideXlab platform.
-
changes in pore structure of metallurgical Cokes under blast furnace conditions
Energy & Fuels, 2016Co-Authors: Xing Xing, Kim Hockings, Harold Rogers, Guangqing Zhang, Paul Zulli, Oleg OstrovskiAbstract:Metallurgical Cokes were subjected to gasification by CO–CO2–N2 gas with blast-furnace-like composition–temperature profile to 1673 K (1400 °C) and annealing under N2 at temperature up to 2273 K (2000 °C). Pore structure of Cokes was examined using image analysis. Porosity and pore size were both enlarged under gasification and annealing conditions. The pore structure change during gasification was mainly a result of the Boudouard reaction; the pore structure development upon annealing was attributed to the reactions of mineral matters with carbon and further devolatilization. Annealing and gasification caused a decrease in average pore roundness, an increase in the fraction of low roundness pores and the increase of coalescence points in the pore area. The degradation of Coke Strength following reaction and annealing was characterized using tensile testing. Both gasification and annealing decreased the mechanical Strength of Coke. Degradation of more reactive Cokes (Cokes C and D) by gasification at 1673...
-
Fractographic approach to metallurgical Coke failure analysis. Part 1: Cokes of single coal origin
Fuel, 2016Co-Authors: Richard Roest, Kim Hockings, Merrick R MahoneyAbstract:Abstract Metallurgical Coke is a complex brittle heterogeneous material consisting of carbon derived from fusible, semi-fusible and inert coal particles that forms a porous composite matrix. This paper presents a novel approach to assess and quantify the breakage behaviour and microstructural weaknesses in a pilot oven metallurgical Coke. The approach uses fractography, a method commonly applied to determine the fracture behaviour and origin(s) in homogeneous materials, such as metals and ceramics. Determination of the fracture origin(s), paths of crack propagation and microstructural weaknesses in such a complex heterogeneous material as metallurgical Coke represents a significant advance in both the application of fractography and the assessment of Coke Strength and breakage behaviour. Identification of the key features that contribute to the Coke’s failure will facilitate better prediction of Coke Strength from coal properties and ultimately optimisation of the coal blending process. Key features and markings have been clearly identified on fracture surfaces that can either be traced back to the fracture origin or give an indication of the type of fracture or stresses to which the Coke has been subjected, including the directionality and Strength of those stresses. These markings include hackle, hackle twist and wallner lines, as well as markings generated by conchoidal and overload fractures. A three-step approach was applied to determine the breakage behaviour in stabilized lumps of the pilot oven Coke, in which fractured Coke surfaces were analysed at the macro, micro and submicron levels. The observed mechanisms of failure were quantified and summarised using a radar diagram.
Seiji Nomura - One of the best experts on this subject based on the ideXlab platform.
-
influence of binder coal tar and pitch addition on coal caking property and Coke Strength
Fuel Processing Technology, 2017Co-Authors: Seiji Nomura, Takashi ArimaAbstract:Abstract In order to increase the usage of semi-soft coking coal, various technologies have been developed and commercialized. Among these, an additive for improving coal caking property (hereinafter referred to as a binder) is promising. Here the mechanism of binders for improving coal caking property and the influence of binder addition to coal with different particle size on caking property and Coke Strength were investigated. The thermogravimetric analysis and dilatometry tests have suggested that as for coal-derived binder, the gas generating from the binder interacts with coal before coal starts to soften and that coal is reformed in-situ during heating by the interaction, which leads to enhancement of caking property. On the other hand, as for petroleum-derived binder, the experiments have implied that the reason why the petroleum-derived binder enhances coal caking properties is that the gas generating as a result of pyrolysis of the petroleum-derived binder “in” the plastic coal helps the plastic coal to swell and become more fluid. Moreover, dilatation differs greatly with coal types and particle size fractions. When the specific dilatation volume of fine coal is equal to that of coarse coal, the Coke structure becomes more homogeneous, which leads to high Strength Coke structure. There is a possibility that under the binder addition ratio being constant, Coke with maximum DI can be obtained by adding binders to fine coal and coarse coal separately so that the specific dilatation volume of fine coal becomes equal to that of coarse coal.
-
the effect of plastic addition on coal caking properties during carbonization
Fuel, 2003Co-Authors: Seiji Nomura, Kenji Kato, Tomoyuki Nakagawa, Ikuo KomakiAbstract:The recycling process of waste plastics using Coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. It was revealed that thermal decomposition products of plastics interacted with bituminous coal during carbonization in Coke ovens. The effect of plastic addition on coal caking property varied with types of plastics. The addition of aliphatic polymers such as polyethylene (PE), polypropylene (PP) and poly(vinyl chloride) (PVC) had only a small effect on coal caking property and Coke Strength and in some cases PE addition increased Coke Strength. On the other hand, the addition of polystyrene (PS), poly(ethylene terephthalate) (PET) and terephtalic acid (TFA) inhibited coal expansion and fusion, decreased maximum fluidity and total dilatation, and deteriorated the Coke Strength. These differences were discussed from the viewpoint of the interaction between thermal decomposition products of plastics and hydrogen in coal. It was suggested that the radical formed as a result of PS or PET thermal decomposition abstracted hydrogen from coal, which resulted in the decrease in coal caking property.
Ikuo Komaki - One of the best experts on this subject based on the ideXlab platform.
-
the effect of plastic addition on coal caking properties during carbonization
Fuel, 2003Co-Authors: Seiji Nomura, Kenji Kato, Tomoyuki Nakagawa, Ikuo KomakiAbstract:The recycling process of waste plastics using Coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. It was revealed that thermal decomposition products of plastics interacted with bituminous coal during carbonization in Coke ovens. The effect of plastic addition on coal caking property varied with types of plastics. The addition of aliphatic polymers such as polyethylene (PE), polypropylene (PP) and poly(vinyl chloride) (PVC) had only a small effect on coal caking property and Coke Strength and in some cases PE addition increased Coke Strength. On the other hand, the addition of polystyrene (PS), poly(ethylene terephthalate) (PET) and terephtalic acid (TFA) inhibited coal expansion and fusion, decreased maximum fluidity and total dilatation, and deteriorated the Coke Strength. These differences were discussed from the viewpoint of the interaction between thermal decomposition products of plastics and hydrogen in coal. It was suggested that the radical formed as a result of PS or PET thermal decomposition abstracted hydrogen from coal, which resulted in the decrease in coal caking property.