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01066 Optical properties of pseudovitrinite; implications for its origin
01 Solid fuels (preparation) 06/01066 Optical properties of pseudovitrinite; implications for its origin Mastalerz, M. and Drobniak, A. International Journal of Coal Geology, 2005, 62, (4), 250 258. A set of Pennsylvanian coals from the North A m e r i c a n coal basins, ranging in vitrinite reflectance from 0.65% to 1.75%, was examined, with special emphasis on the optical p r o p e r t i e s of pseudovitrinite. The results suggest that pseudovitrinite originates from the same material as telocollinite. Slits in the pseudovitrinite seem to have originated in situ due to low-temperature oxidation of woody material; their opening might have been facilitated by devolatilization d u r i n g coalification. The d o m i n a n t orientation of the slits is p e r p e n d i c u l a r to bedding. The intensity and orientation of the slits in pseudovitrinite could be i m p o r t a n t factors in predicting coalbed gas extraction from coal.
06•01067 Predicting the handlability of a coal blend from measurements on the source coals Zhong, Z. et al. Fuel, 2005, 84, (17), 2267 2274. Coals may be blended at mines to m e e t contractual criteria set by the client. In formulating a blend, the criterion that is hardest to m e e t is often the handlability because it is difficult to predict. Most research on coal handling treats coal handlability as a property to be m e a s u r e d for a given material, and there a p p e a r to have been very few attempts to predict the consequences of blending choices, or to use such information to optimize coal blends for the different contractual requirements. This p a p e r presents w h a t is believed to be the first study to explore the causal relationships in coal blending, to use these to predict the handlability of a blend, and to establish the basis n e e d e d to optimize b l e n d i n g choices. The ultimate goal of this work is an algorithm that can be used in on-line real time choices in coal b l e n d i n g operations, either at mines or at power stations.
06/01068 vitrains
Surface properties of photo-oxidized bituminous
Mitchell, G. D. et al. International Journal of Coal Geology, 2005, 62, (1 2), 33 47. The principal aim of this research was to d e t e r m i n e whether correlations could be established a m o n g surface oxygen functionality, hydrophobicity induced by photo-oxidation, and m e a s u r e m e n t s of fluorescence alteration. Polished surfaces of vitrain bands were photooxidized using a blue-light flux and then changes in surface p r o p e r t i e s were measured. The data obtained reveal significant variations d e p e n d i n g upon the level of surface oxidation. There is a progressive and significant increase in the a m o u n t of near-surface oxygen concentration which a p p e a r to lower the hydrophobicity as shown by contact angle m e a s u r e m e n t s . A l t h o u g h this influence d i m i n i s h e d as coal r a n k increased, the level of oxygen u p t a k e was about the same, suggesting that the type of oxygen functionality formed during oxidation may be of great i m p o r t a n c e in modifying surface hydrophobicity. Changes in functional-group chemistry showed a general increase in the concentration of carbonyl-containing groups while those of CH2 groups decreased. All of these observations follow the trends observed in previous investigations of naturally w e a t h e r e d coals. The photo-oxidation technique also resulted in the d e v e l o p m e n t of phenolic, ester and anhydride moieties instead of the expected e m p l a c e m e n t of carboxylic acid groups which are normally associated with naturally w e a t h e r e d coals. Increase in the concentration of esters and anhydrides would be expected to result in a more hydrophobic surface, the opposite of what was actually encountered.
Preparation 06/01069 A new method for determining the conversion of low-ash coals using synthetic ash as a tracer Ballantyne, T. R. et al. Fuel, 2005, 84, (14 15), 1980 1985. Victorian brown coal represents a significant resource for power g e n e r a t i o n in Australia. The typical ash content for these coals can be as low as 1% (dry basis). While low ash content is obviously a major advantage for the utilization of these coals, it is a p r o b l e m for researchers in that the low ash content leads to large inaccuracies when using the 'ash tracer' m e t h o d to d e t e r m i n e coal conversion in flow reactors. To address this problem, a modified ash tracer m e t h o d has been developed to d e t e r m i n e coal conversion which involves a d d i n g perlite as an artificial ash to the coal. This m e t h o d has been successfully applied to measure coal conversion during the pyrolysis of Loy Y a n g coal in a drop tube furnace.
06/01070 A pilot-scale flotation column to produce beneficiated coal fractions having high concentration of vitrinite maceral Barraza, J. and Pifieres, J. Fuel, 2005, 84, (14 15), 1879 1883.
A pilot-scale flotation column was used to produce beneficiated vitrinite-rich fractions from two coal samples from south western Colombia, G u a c h i n t e and Yolanda. The coal samples of less than 38 m m in size were processed in the flotation column at p H ranging from 7 to 11 using various concentrations of a particular frother. Results showed that, using a single stage separation, m a x i m u m mass yield of float fractions was 84.6% w/w for G u a c h i n t e coal and 55.5% w/w for Yolanda. The m a x i m u m ash removals were 71.7 and 76.5% for G u a c h i n t e and Y o l a n d a coals, respectively. This corresponds to sulphur removals of 63.2% for G u a c h i n t e coal and 75.4% for Y o l a n d a coal. The highest concentration of vitrinite was obtained using Y o l a n d a coal. It was in the order of 99.8% at neutral p H and when using the highest frother concentration. This result is the highest concentration of vitrinite maceral reported in the literature using a pilot-scale flotation column.
06/01071 Behaviour of inorganic matter during heating of Bulgarian coals, 1, Lignites Vassileva, C. G. and Vassilev, S. V. Fuel Processing Technology, 2005, 86, (12 13), 1297 1333. Bulgarian lignites (Maritza East, Maritza West, Sofia) were gradually h e a t e d u n d e r air from 100°C to their fluid ash fusion t e m p e r a t u r e s (1200 1300°C) via 100°C intervals and the behaviour of their inorganic matter (IM) was studied. The pre-existing minerals and newly formed inorganic phases in the oxidation and combustion products (OCPs) of these coals were identified and the behaviour of 38 minerals and phases was described. The lignites reveal low detrital a b u n d a n c e and high authigenic mineralization with sulphide sulphate or carbonate tendencies. The I M of lignites is composed mainly of quartz, kaolinite, gypsum, calcite, and pyrite, while the other minerals identified have subordinate occurrence. The IM of OCPs includes also various newly formed phases such as glass, a m o r p h o u s clay material, mullite, hematite, Ca and C ~ M g silicates, cristobalite, tridymite, magnetite, Ca and Mg oxides hydroxides, anhydrite, and others originating from the heating of these lignites or storage of their OCPs. The physicochemical processes and t e m p e r a t u r e s that result in the formation of new phases in OCPs are described. The relationships between the ash fusion behaviour and chemical and m i n e r a l composition of the lignites are also discussed.
06•01072 leaching
Biodesulphurisation of high sulphur coal by heap
Cara, J. et al. Fuel, 2005, 84, (14 15), 1905 1910. The b i o d e s u l p h u r i z a t i o n of coal carried out in pile could be an interesting option to clean coal. In view of the good results obtained in biodesulphurization test column at lab scale on a sample of semianthracite coal that proceed of an industrial p l a n t with a high sulphur content, mainly pyritic sulphur, the feasibility of the process at pilot p l a n t scale was studied. The pile was formed with 6 ton of gravity middlings coal sample with a grain size 12+0.5 m m from S.A. H u l l e r a V a s c o - L e o n e s a industrial plant. The coal has a total sulphur content of 3.78% and a pyritic sulphur content of 2.88%, the rest of sulphur is organic sulphur. The biodesulphurization process in pilot p l a n t follows three stages: stabilization of the pile, biodesulphurization and washing. H e a p was sampled twice d u r i n g stabilization stage, at the end of desulphurization process and finally once washed. A pyritic sulphur removal of 39% and total sulphur removal of 23% was obtained. To complete the bioleaching process, the t r e a t m e n t of p u r g e of leachate was carried out with the objective to recycling to head of process. The best t r e a t m e n t was a p r e - t r e a t m e n t of the leachate until p H 4, and further t r e a t m e n t by reverse osmosis of the clarified water. C o m p a r i n g this process with conventional precipitation to reach disposal limits, the reagents c o n s u m p t i o n and sludges were reduced considerably and due to the high quality of p e r m e a t e it permits to recycle it to head of process.
06/01073 Catalytic decomposition of ammonia gas with metal cations present naturally in low rank coals Xu, C. et al. Fuel, 2005, 84, (14 15), 1957 1967. A novel hot gas cleanup m e t h o d to d e c o m p o s e a low concentration of NH3 to N2 with m e t a l cations p r e s e n t inherently in low rank coals has been studied with a quartz reactor u n d e r the conditions of 750 850°C, 0.1 M P a and high space velocity of 45,000 h-1. Each coal is pyrolysed at 900°C to p r e p a r e the char, which is subjected to the decomposition of 2000 p p m NH3 after p r e t r e a t m e n t with H2. All of five chars examined p r o m o t e NH3 decomposition in inert gas, but the p r o m o t i o n effect depends strongly on the kind of char and can correlate more closely with the Fe content than with the Ca content. This result may indicate that the Fe plays a crucial role in the reaction. A commercial activated carbon with a very low Fe content of <0.05 w t % exhibits lower conversion of NH3 to N2 than five chars. The T E M pictures reveal the formation of nanoscale particles of Fe and Ca c o m p o n e n t s on a brown coal char that provides the largest catalytic performance. The char maintains the high conversion level of 80% during 25 h reaction at 750°C and achieves the complete decomposition of NH3 at 850°C. The
Fuel and Energy Abstracts
May 2006
163
06•01067 Predicting the handlability of a coal blend from measurements on the source coals Zhong, Z. et al. Fuel, 2005, 84, (17), 2267 2274. Coals may be blended at mines to m e e t contractual criteria set by the client. In formulating a blend, the criterion that is hardest to m e e t is often the handlability because it is difficult to predict. Most research on coal handling treats coal handlability as a property to be m e a s u r e d for a given material, and there a p p e a r to have been very few attempts to predict the consequences of blending choices, or to use such information to optimize coal blends for the different contractual requirements. This p a p e r presents w h a t is believed to be the first study to explore the causal relationships in coal blending, to use these to predict the handlability of a blend, and to establish the basis n e e d e d to optimize b l e n d i n g choices. The ultimate goal of this work is an algorithm that can be used in on-line real time choices in coal b l e n d i n g operations, either at mines or at power stations.
06/01068 vitrains
Surface properties of photo-oxidized bituminous
Mitchell, G. D. et al. International Journal of Coal Geology, 2005, 62, (1 2), 33 47. The principal aim of this research was to d e t e r m i n e whether correlations could be established a m o n g surface oxygen functionality, hydrophobicity induced by photo-oxidation, and m e a s u r e m e n t s of fluorescence alteration. Polished surfaces of vitrain bands were photooxidized using a blue-light flux and then changes in surface p r o p e r t i e s were measured. The data obtained reveal significant variations d e p e n d i n g upon the level of surface oxidation. There is a progressive and significant increase in the a m o u n t of near-surface oxygen concentration which a p p e a r to lower the hydrophobicity as shown by contact angle m e a s u r e m e n t s . A l t h o u g h this influence d i m i n i s h e d as coal r a n k increased, the level of oxygen u p t a k e was about the same, suggesting that the type of oxygen functionality formed during oxidation may be of great i m p o r t a n c e in modifying surface hydrophobicity. Changes in functional-group chemistry showed a general increase in the concentration of carbonyl-containing groups while those of CH2 groups decreased. All of these observations follow the trends observed in previous investigations of naturally w e a t h e r e d coals. The photo-oxidation technique also resulted in the d e v e l o p m e n t of phenolic, ester and anhydride moieties instead of the expected e m p l a c e m e n t of carboxylic acid groups which are normally associated with naturally w e a t h e r e d coals. Increase in the concentration of esters and anhydrides would be expected to result in a more hydrophobic surface, the opposite of what was actually encountered.
Preparation 06/01069 A new method for determining the conversion of low-ash coals using synthetic ash as a tracer Ballantyne, T. R. et al. Fuel, 2005, 84, (14 15), 1980 1985. Victorian brown coal represents a significant resource for power g e n e r a t i o n in Australia. The typical ash content for these coals can be as low as 1% (dry basis). While low ash content is obviously a major advantage for the utilization of these coals, it is a p r o b l e m for researchers in that the low ash content leads to large inaccuracies when using the 'ash tracer' m e t h o d to d e t e r m i n e coal conversion in flow reactors. To address this problem, a modified ash tracer m e t h o d has been developed to d e t e r m i n e coal conversion which involves a d d i n g perlite as an artificial ash to the coal. This m e t h o d has been successfully applied to measure coal conversion during the pyrolysis of Loy Y a n g coal in a drop tube furnace.
06/01070 A pilot-scale flotation column to produce beneficiated coal fractions having high concentration of vitrinite maceral Barraza, J. and Pifieres, J. Fuel, 2005, 84, (14 15), 1879 1883.
A pilot-scale flotation column was used to produce beneficiated vitrinite-rich fractions from two coal samples from south western Colombia, G u a c h i n t e and Yolanda. The coal samples of less than 38 m m in size were processed in the flotation column at p H ranging from 7 to 11 using various concentrations of a particular frother. Results showed that, using a single stage separation, m a x i m u m mass yield of float fractions was 84.6% w/w for G u a c h i n t e coal and 55.5% w/w for Yolanda. The m a x i m u m ash removals were 71.7 and 76.5% for G u a c h i n t e and Y o l a n d a coals, respectively. This corresponds to sulphur removals of 63.2% for G u a c h i n t e coal and 75.4% for Y o l a n d a coal. The highest concentration of vitrinite was obtained using Y o l a n d a coal. It was in the order of 99.8% at neutral p H and when using the highest frother concentration. This result is the highest concentration of vitrinite maceral reported in the literature using a pilot-scale flotation column.
06/01071 Behaviour of inorganic matter during heating of Bulgarian coals, 1, Lignites Vassileva, C. G. and Vassilev, S. V. Fuel Processing Technology, 2005, 86, (12 13), 1297 1333. Bulgarian lignites (Maritza East, Maritza West, Sofia) were gradually h e a t e d u n d e r air from 100°C to their fluid ash fusion t e m p e r a t u r e s (1200 1300°C) via 100°C intervals and the behaviour of their inorganic matter (IM) was studied. The pre-existing minerals and newly formed inorganic phases in the oxidation and combustion products (OCPs) of these coals were identified and the behaviour of 38 minerals and phases was described. The lignites reveal low detrital a b u n d a n c e and high authigenic mineralization with sulphide sulphate or carbonate tendencies. The I M of lignites is composed mainly of quartz, kaolinite, gypsum, calcite, and pyrite, while the other minerals identified have subordinate occurrence. The IM of OCPs includes also various newly formed phases such as glass, a m o r p h o u s clay material, mullite, hematite, Ca and C ~ M g silicates, cristobalite, tridymite, magnetite, Ca and Mg oxides hydroxides, anhydrite, and others originating from the heating of these lignites or storage of their OCPs. The physicochemical processes and t e m p e r a t u r e s that result in the formation of new phases in OCPs are described. The relationships between the ash fusion behaviour and chemical and m i n e r a l composition of the lignites are also discussed.
06•01072 leaching
Biodesulphurisation of high sulphur coal by heap
Cara, J. et al. Fuel, 2005, 84, (14 15), 1905 1910. The b i o d e s u l p h u r i z a t i o n of coal carried out in pile could be an interesting option to clean coal. In view of the good results obtained in biodesulphurization test column at lab scale on a sample of semianthracite coal that proceed of an industrial p l a n t with a high sulphur content, mainly pyritic sulphur, the feasibility of the process at pilot p l a n t scale was studied. The pile was formed with 6 ton of gravity middlings coal sample with a grain size 12+0.5 m m from S.A. H u l l e r a V a s c o - L e o n e s a industrial plant. The coal has a total sulphur content of 3.78% and a pyritic sulphur content of 2.88%, the rest of sulphur is organic sulphur. The biodesulphurization process in pilot p l a n t follows three stages: stabilization of the pile, biodesulphurization and washing. H e a p was sampled twice d u r i n g stabilization stage, at the end of desulphurization process and finally once washed. A pyritic sulphur removal of 39% and total sulphur removal of 23% was obtained. To complete the bioleaching process, the t r e a t m e n t of p u r g e of leachate was carried out with the objective to recycling to head of process. The best t r e a t m e n t was a p r e - t r e a t m e n t of the leachate until p H 4, and further t r e a t m e n t by reverse osmosis of the clarified water. C o m p a r i n g this process with conventional precipitation to reach disposal limits, the reagents c o n s u m p t i o n and sludges were reduced considerably and due to the high quality of p e r m e a t e it permits to recycle it to head of process.
06/01073 Catalytic decomposition of ammonia gas with metal cations present naturally in low rank coals Xu, C. et al. Fuel, 2005, 84, (14 15), 1957 1967. A novel hot gas cleanup m e t h o d to d e c o m p o s e a low concentration of NH3 to N2 with m e t a l cations p r e s e n t inherently in low rank coals has been studied with a quartz reactor u n d e r the conditions of 750 850°C, 0.1 M P a and high space velocity of 45,000 h-1. Each coal is pyrolysed at 900°C to p r e p a r e the char, which is subjected to the decomposition of 2000 p p m NH3 after p r e t r e a t m e n t with H2. All of five chars examined p r o m o t e NH3 decomposition in inert gas, but the p r o m o t i o n effect depends strongly on the kind of char and can correlate more closely with the Fe content than with the Ca content. This result may indicate that the Fe plays a crucial role in the reaction. A commercial activated carbon with a very low Fe content of <0.05 w t % exhibits lower conversion of NH3 to N2 than five chars. The T E M pictures reveal the formation of nanoscale particles of Fe and Ca c o m p o n e n t s on a brown coal char that provides the largest catalytic performance. The char maintains the high conversion level of 80% during 25 h reaction at 750°C and achieves the complete decomposition of NH3 at 850°C. The
Fuel and Energy Abstracts
May 2006
163