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Porosity of bituminous coals
01 Solid fuels (sources, winning, properties) occurrence of weak autoxidation processes has been observed in the coal seam at a depth from 3 to 5 m. Mierinite whose percentage is relatively high has been formed as a result of high temperature processes that take place in the peat. The higher amount of imerinite macerals predetermines the higher oxidative stability of this coal.
02/01272 Peculiarities of gas content and metamorphic changes in coals in the southwest coal region of the LvovVolyn Basin Kruglova, R.L. Geol. Geokhim. Goryuch. Kopalin, 1999, 4, 70-75. (In Ukrainian) Methane content and metamorphism of coal, both regionally and in the stratigraphic section of coal seam, were studied. A close connection of the methane content with the coalification degree and coal depth was established.
02/01273
Porosity of bituminous coals
Strugala, A. Gospod. Surowcami Miner, 2001, 17, (2), 5-17. (In Polish) The results of the total pore volume examination of 18 Polish bituminous coals are presented. The research was carried out by mercury porosimetry in connection with the mercury and helium density measurements. For the tested population of coals it was stated that there occurred a correlation between the volume of pores with the radius smaller than 7.5 nm and the mass proportion and structure of the organic matter of coal. The structure was characterized by means of a structural index similar to the one suggested by Oberlin. In the case of pores greater than 7.5 nm it was proved that their volume depended only on the mass proportion in coal of both of the basic components, i.e. organic and mineral matter. Moreover, it was stated that the predominant volume of pores in the examined coals was connected with the pores with radius r _< 2500 nm.
02/01274 Prediction of the natural moisture content of brown coals Fafara, Z. and Twardowski, K. Zesz. Nauk. Politech. S/ask., Gorn., 2000, 246, (1), 101-110. (In Polish) The natural humidity of lignites belongs to the most important technology parameters of coal, especially coal power. The literature abounds in numerous models for assessing the parameter based on the known values of other parameters which were detected in a standard way. As a rule, they are generally of local character. An attempt was made to create a universal regression model for predicting the natural humidity of lignites based on ash content and depth of deposition. A non-linear asymptotic model was elaborated. Its verification shows a high geological efficiency.
02/01275 Preliminary characterization of metalloporphyrins in coals - Nigeria Olajire, A.A. and Adabanija, M.A. Nafta (Zagreb, Croatia), 2001, 52, (5), 167-170. Metalloporphyrins were isolated from Nigerian coal minerals by solvent extraction followed by SiO2 liquid chromatography. Electronic absorption spectrophotometry was used in the detection of the nature of the isolated complexes. The major elements as determined by atmospheric absorption spectroscopy were manganese, iron and gallium. Rhodotype visible spectra were obtained for some of the traction, and the presence of rhodofying 1 groups were confirmed by the carbonyl absorption band at 1715 cm (5.8 t~m) in their IR spectra.
02/01276 Problems of coal utilization in Romanian thermopower plants C~rdu, M. and Sandu, D. Energy Conversion and Management, 2001, 42, (18), 2097-2108. In this paper, the key problems facing coal utilization in Romanian thermopower plants (TPPs) are presented, reflecting the economic and technical difficulties associated with this. Presented are the results of Romanian researches for resolving the necessary problems regarding ecological standards and obtaining good efficiency in TPPs functioning with coal. Proposals are made for application of such researches.
02/01277 Quantitative evaluation of structural transformations in raw coals on heat-treatment using HRTEM technique Sharma, A. et al. Fuel, 2001, 80, (10), 1467-1473. The structural transformation in Beulah-Zap (BZ), Illinois (IL) no. 6. Upper Freeport (UF) and Pocahontas (POC) no. 3 coals on heattreatment at 427,800 and 1200°C were examined by high-resolution transmission electron microscopy (HRTEM) technique. The stacking number and layer sizes of heat-treated coals were evaluated. The structural change in coal strongly depends on whether a coal undergoes plastic stage or not. BZ coal does not show plasticity and accordingly no significant change was observed even at 1200°C heat-treatment temperature. IL, U F and POC coals showed increase in ordering of layers when heat-treated depending upon their degree of plasticity. U F
coal with highest plasticity deveioped highly ordered structures similar to graphitizable carbon. For IL and POC coals with very little plasticity, the change in structure at high temperature was also found to depend on the stacking orders present in the initial raw coals. The H R T E M technique can successfully quantify the structural change in coal on heat-treatment.
02/01278
Removing coal radicals by chemical reduction
Larsen, J.W. et al. Energy Fuels, 2001, 15, (5), 1225-1226. The radical population of Wyodak coal was decreased by reaction with the reducing agents Sml2, Ybl2, and CrCI2. The latter is the most effective, removing 67% of the radicals. It is also the easiest to prepare. The swelling of Wyodak coal in toluene, THF, and pyridine is independent of the coal's radical population demonstrating that radical sites are not responsible for intermolecular associative interactions.
02/01279 Review of methods for measurement of coal quality parameters Pielot, J. Zesz. Nauk. Politech. S/ask., Garn., 2000, 246, (3), 425-436. (In Polish) This review considers methods of measuring coal quality parameters. Problems concerning coal sampling and measurement accuracy of quality parameters are discussed.
02/01280 Seasonal variation in the biomass and agar yield from Gracilaria cervicornis and Hydropuntia cornea from Brazil Marinho-Soriano, E. et al. Bioresource Technology, 2001, 77, (2), 115120. Seasonality of biomass and agar yield from two agarophytes (G. cervicornis and H. cornea) was determined. The biomass from G. cervicornis was higher (390 g m-2) during the dry season and lower during the rainy season (129 g m2). The data analysis for G. cervicornis revealed a significant seasonal variation (P < 0.05) H. cornea did not show a clear seasonal variation and was present only from March to August. The peak in biomass for this species was recorded in April (383 g m -2) and was significantly different from the other months (P < 0.05). The agar yield for G. cervicornis varied from 11% to 20%, with generally higher Values recorded during the dry season. The agar yield showed a highly significant variation (P < 0.001). Agar yield from H. cornea ranged from 29% to 41%, with a peak recorded in June. The results above indicate that H. cornea can be considered a good candidate for commercial use.
02/01281 Selectivity in cation exchange property of heattreated brown coals Murakami, K. et al. Fuel, 2001, 80, (4), 599-605. The selectivity in cation exchange of Loy Yang brown coal treated at 50-250°C was studied in an aqueous solution containing two kinds of metallic ions to clarify the effects of the heat treatment temperatures of coal, pH of the exchange solution, and addition of acetone to the exchange solution. Four divalent metallic ions of Co 2 , Mg z , Ni 2+ Ca 2+, mainly the former two, were used as exchange cations. The amount of Co 2+ adsorption (the extent of cation exchange for Co 2+, Co-ECE) from the Co-Mg mixed solution at pH 6 for the coal treated at 50°C was 1.15 mmol g-coal 1, almost the same value as that from the single Co z+ ionic solution, whereas the Mg-ECE from the Co-Mg mixed solution decreased to 1/6 of that from the single Mg 2 ionic solution which was 0.8 mmol 8 t, indicating that the ability of cation exchange of Co 2+ is much higher than that of Mg 2+, the selectivity of Co z+ (the ratio of the Co-ECE to the sum of the Co-ECE and the MgECE) about 90%. With decreasing pH of the solution, however, the selectivity of Co 2+ decreased. The selectivity of Co 2 in the low pH region between 2 and 5.5 decreased further for the heat-treated coal samples at higher temperature. On the other hand, in the higher pH region, the selectivity of Co 2+ w a s recovered to larger than 70% independent of heat treatment temperatures. By addition of acetone to the exchange solution, the selectivity of Co 2+ was also recovered up to about 50% even in the low pH region. These changes of the selectivity in cation exchange are discussed based on the structural changes of brown coal.
02/01282 Significance of organic matter in recording paleoenvironmental conditions of the Sara Formation coal sequence, Maghara Area, North Sinai, Egypt Mostafa, A.R. and Younes, M.A. Int. J. Coal Geol., 2001,47, (1), 9-21. Five coal and shale core samples of the Middle Jurassic Safa Formation were taken from a newly drilled water well at the depth interval from 191 to 208 m, and have been investigated in this study. Detailed organic and inorganic geochemical analyses of the Safa Formation reveal no significant differences between the upper seams and the main seam. The extracts, of the coal samples have an unusual n-alkane distribution; the GC traces are dominated by unusual compounds eluting between nCi9 and n-C21. These compounds are thought to be diterpanes, which suggest significant conifer contributions to the coals. Higher amounts
Fuel and Energy Abstracts
May 2002 167
02/01272 Peculiarities of gas content and metamorphic changes in coals in the southwest coal region of the LvovVolyn Basin Kruglova, R.L. Geol. Geokhim. Goryuch. Kopalin, 1999, 4, 70-75. (In Ukrainian) Methane content and metamorphism of coal, both regionally and in the stratigraphic section of coal seam, were studied. A close connection of the methane content with the coalification degree and coal depth was established.
02/01273
Porosity of bituminous coals
Strugala, A. Gospod. Surowcami Miner, 2001, 17, (2), 5-17. (In Polish) The results of the total pore volume examination of 18 Polish bituminous coals are presented. The research was carried out by mercury porosimetry in connection with the mercury and helium density measurements. For the tested population of coals it was stated that there occurred a correlation between the volume of pores with the radius smaller than 7.5 nm and the mass proportion and structure of the organic matter of coal. The structure was characterized by means of a structural index similar to the one suggested by Oberlin. In the case of pores greater than 7.5 nm it was proved that their volume depended only on the mass proportion in coal of both of the basic components, i.e. organic and mineral matter. Moreover, it was stated that the predominant volume of pores in the examined coals was connected with the pores with radius r _< 2500 nm.
02/01274 Prediction of the natural moisture content of brown coals Fafara, Z. and Twardowski, K. Zesz. Nauk. Politech. S/ask., Gorn., 2000, 246, (1), 101-110. (In Polish) The natural humidity of lignites belongs to the most important technology parameters of coal, especially coal power. The literature abounds in numerous models for assessing the parameter based on the known values of other parameters which were detected in a standard way. As a rule, they are generally of local character. An attempt was made to create a universal regression model for predicting the natural humidity of lignites based on ash content and depth of deposition. A non-linear asymptotic model was elaborated. Its verification shows a high geological efficiency.
02/01275 Preliminary characterization of metalloporphyrins in coals - Nigeria Olajire, A.A. and Adabanija, M.A. Nafta (Zagreb, Croatia), 2001, 52, (5), 167-170. Metalloporphyrins were isolated from Nigerian coal minerals by solvent extraction followed by SiO2 liquid chromatography. Electronic absorption spectrophotometry was used in the detection of the nature of the isolated complexes. The major elements as determined by atmospheric absorption spectroscopy were manganese, iron and gallium. Rhodotype visible spectra were obtained for some of the traction, and the presence of rhodofying 1 groups were confirmed by the carbonyl absorption band at 1715 cm (5.8 t~m) in their IR spectra.
02/01276 Problems of coal utilization in Romanian thermopower plants C~rdu, M. and Sandu, D. Energy Conversion and Management, 2001, 42, (18), 2097-2108. In this paper, the key problems facing coal utilization in Romanian thermopower plants (TPPs) are presented, reflecting the economic and technical difficulties associated with this. Presented are the results of Romanian researches for resolving the necessary problems regarding ecological standards and obtaining good efficiency in TPPs functioning with coal. Proposals are made for application of such researches.
02/01277 Quantitative evaluation of structural transformations in raw coals on heat-treatment using HRTEM technique Sharma, A. et al. Fuel, 2001, 80, (10), 1467-1473. The structural transformation in Beulah-Zap (BZ), Illinois (IL) no. 6. Upper Freeport (UF) and Pocahontas (POC) no. 3 coals on heattreatment at 427,800 and 1200°C were examined by high-resolution transmission electron microscopy (HRTEM) technique. The stacking number and layer sizes of heat-treated coals were evaluated. The structural change in coal strongly depends on whether a coal undergoes plastic stage or not. BZ coal does not show plasticity and accordingly no significant change was observed even at 1200°C heat-treatment temperature. IL, U F and POC coals showed increase in ordering of layers when heat-treated depending upon their degree of plasticity. U F
coal with highest plasticity deveioped highly ordered structures similar to graphitizable carbon. For IL and POC coals with very little plasticity, the change in structure at high temperature was also found to depend on the stacking orders present in the initial raw coals. The H R T E M technique can successfully quantify the structural change in coal on heat-treatment.
02/01278
Removing coal radicals by chemical reduction
Larsen, J.W. et al. Energy Fuels, 2001, 15, (5), 1225-1226. The radical population of Wyodak coal was decreased by reaction with the reducing agents Sml2, Ybl2, and CrCI2. The latter is the most effective, removing 67% of the radicals. It is also the easiest to prepare. The swelling of Wyodak coal in toluene, THF, and pyridine is independent of the coal's radical population demonstrating that radical sites are not responsible for intermolecular associative interactions.
02/01279 Review of methods for measurement of coal quality parameters Pielot, J. Zesz. Nauk. Politech. S/ask., Garn., 2000, 246, (3), 425-436. (In Polish) This review considers methods of measuring coal quality parameters. Problems concerning coal sampling and measurement accuracy of quality parameters are discussed.
02/01280 Seasonal variation in the biomass and agar yield from Gracilaria cervicornis and Hydropuntia cornea from Brazil Marinho-Soriano, E. et al. Bioresource Technology, 2001, 77, (2), 115120. Seasonality of biomass and agar yield from two agarophytes (G. cervicornis and H. cornea) was determined. The biomass from G. cervicornis was higher (390 g m-2) during the dry season and lower during the rainy season (129 g m2). The data analysis for G. cervicornis revealed a significant seasonal variation (P < 0.05) H. cornea did not show a clear seasonal variation and was present only from March to August. The peak in biomass for this species was recorded in April (383 g m -2) and was significantly different from the other months (P < 0.05). The agar yield for G. cervicornis varied from 11% to 20%, with generally higher Values recorded during the dry season. The agar yield showed a highly significant variation (P < 0.001). Agar yield from H. cornea ranged from 29% to 41%, with a peak recorded in June. The results above indicate that H. cornea can be considered a good candidate for commercial use.
02/01281 Selectivity in cation exchange property of heattreated brown coals Murakami, K. et al. Fuel, 2001, 80, (4), 599-605. The selectivity in cation exchange of Loy Yang brown coal treated at 50-250°C was studied in an aqueous solution containing two kinds of metallic ions to clarify the effects of the heat treatment temperatures of coal, pH of the exchange solution, and addition of acetone to the exchange solution. Four divalent metallic ions of Co 2 , Mg z , Ni 2+ Ca 2+, mainly the former two, were used as exchange cations. The amount of Co 2+ adsorption (the extent of cation exchange for Co 2+, Co-ECE) from the Co-Mg mixed solution at pH 6 for the coal treated at 50°C was 1.15 mmol g-coal 1, almost the same value as that from the single Co z+ ionic solution, whereas the Mg-ECE from the Co-Mg mixed solution decreased to 1/6 of that from the single Mg 2 ionic solution which was 0.8 mmol 8 t, indicating that the ability of cation exchange of Co 2+ is much higher than that of Mg 2+, the selectivity of Co z+ (the ratio of the Co-ECE to the sum of the Co-ECE and the MgECE) about 90%. With decreasing pH of the solution, however, the selectivity of Co 2+ decreased. The selectivity of Co 2 in the low pH region between 2 and 5.5 decreased further for the heat-treated coal samples at higher temperature. On the other hand, in the higher pH region, the selectivity of Co 2+ w a s recovered to larger than 70% independent of heat treatment temperatures. By addition of acetone to the exchange solution, the selectivity of Co 2+ was also recovered up to about 50% even in the low pH region. These changes of the selectivity in cation exchange are discussed based on the structural changes of brown coal.
02/01282 Significance of organic matter in recording paleoenvironmental conditions of the Sara Formation coal sequence, Maghara Area, North Sinai, Egypt Mostafa, A.R. and Younes, M.A. Int. J. Coal Geol., 2001,47, (1), 9-21. Five coal and shale core samples of the Middle Jurassic Safa Formation were taken from a newly drilled water well at the depth interval from 191 to 208 m, and have been investigated in this study. Detailed organic and inorganic geochemical analyses of the Safa Formation reveal no significant differences between the upper seams and the main seam. The extracts, of the coal samples have an unusual n-alkane distribution; the GC traces are dominated by unusual compounds eluting between nCi9 and n-C21. These compounds are thought to be diterpanes, which suggest significant conifer contributions to the coals. Higher amounts
Fuel and Energy Abstracts
May 2002 167