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03037 Modes of occurrence of mercury in coals from Guizhou, China
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00/03028 Electrical charge loss during pyrolysis of single coal particles Krammer, G. el crl. Fir<,/. 1999. 78, (IO), 1231-1235. Westerholt and Ibbenburen coal particles were devolatilized by means of a laser using an electrodynamic balance. The devolatilization occurred at ambient pressure and in a pure nitrogen atmosphere. The heating rate was moderate below 100 K/s. The particle temperature and the balancing voltage (to keep a single particle in the centre of the balance) were measured continuously. Parttcle size and shape, and the aerodynamic drag force were measured before and after the reaction. Charge loss of the reacted particle was determined and it was found to be proportional to weight loss, indicating that at least a fraction of the evolved devolatilization products can carry charge which seems only to be possible for high molecular weight products such as a condensed phase.
00103029 Gamma ash and moisture content indicator for coal analysis Kubicek, P. et 01.S/I. VedPr. Vys Sk Banskr-Tech. Univ. Ostrava, Rah Horn.-Geol., 1998, 44, (I). 47-53. (In Czech) This work examines the principle of combining absorption and scattering of low and medium energy gamma radiation in the determination of ash and moisture content of bituminous coal on conveyor belts. Both theoretical analysis and laboratory results obtained in the coal preparation plant are presented. An approximate determination of moisture content is possible provided that homogeneous material is carried by conveyor belt, the granulation of coal and its feed rate remain constant and the stability of scintillation detectors is sufficient. The accuracy of determination of moisture content of bituminous with maximum grain size coal of 50 mm (80% of less than 10 mm) was 1.9%.
00/03030 Gamma isotopic analysis of the coals and ashes from coal fired power plants of Turkey Akyuz, T. et al. C-rch. J. Phys., 1999, 49, 435-438. Gamma-isotopic analysis of the ashes produced by the combustion of lignite in power stations of Turkey together with the parent coal samples was performed with the aim to estimate its potential adverse impacts on human health. Gamma-isotopic analysfs indicated that all samples co:ta&d ZZ”Ra (coal samples: 89-14: Bq kg , ash samples: IS_;26 ,B,s kg ), U (coal ash samples: 9-33 pg g ), Th (coal samples: samples: 2-4 pg g 1-9 pg~ ‘; ash samples’: 8-12 pg g ‘), and 4(1K(coal samples: 26-67 Bq kg ‘; ash samples: not detected). However, ‘34Cs and 13’Cs were not found in the samples.
00103031 Impact of sulphur and trace element geochemistry on the utilization of a marine-influenced coal - case study from the South Wales Variscan foreland basin Gayer, R. A. et ul. Int. J. Coal Geol., 1999, 40, (2-3), 151-174. The analysis of incremental channel samples through two high volatile bituminous coal seams, the Amman Rider and Bute seams, below and above the Vanderbeckei Marine Band at the Westphalian A/B boundary, has been done using proximate petrography, inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and SEM with energy-dispersive X-ray (SEM-EDX) techniques, The results show that both coals are vitrinite-rich and indicate a similar history of paleomire development, with a period of falling water tables towards the middle plies of each seam. Mean sulfur contents in the coal with the marine roof, the Amman Rider seam (4.19 wt%) are almost four times higher than in the coal with a non-marine roof, the Bute seam (1.09 wt%), implying that high sulfur contents are derived from sea water sulfate. In both coals, sulfur is predominantly in the form of pyritic sulfur. Both syngenetic, framboidal and euhedral crystals, and epigenetic vein and cleat-fill pyrite are present. Relatively constant levels of organic sulfur at around 2% have been recorded in the Amman Rider seam. Sulfur levels in the basal and top plies of each seam are at least twice that of the ply with the lowest sulfur content in the seam, reflecting the stages in paleomire development most strongly influenced by sulfatecontaining waters. Thorium/uranium ratios are below 2.9 in the coal with a marine roof, the Amman Rider seam, indicating an enrichment of uranium from sea water, most marked at the top and bottom of the seam. The seam without a marine roof shows thorium/uranium ratios between 2.5 and 4.9, indicating mild marine enrichment of uranium. The concentrations of environmentally significant trace elements (ESEs) are correlated with either the ash or sulfur contents, or both. The correlation between sulfur and lead, arsenic, copper, nickel in the coal with a marine roof implies an origin of these ESEs from sea water and their mode of occurrence in sulfide minerals. Most ESEs in this coal are present at levels at least twice that of the global average in coals, the exceptions being lead and zinc which have concentrations less than half the global average. By contrast, the coal without a manne roof and with lower sulfur contents has most ESEs present at concentrations less than a third of the global average, the exceptions being nickel and copper. Diagenetic hydrothermal activity is documented ifi the middle ply of the coal with a marine roof. This hydrothermal system redistributed the sulfur, lead and arsenic in this ply. The principal utilization of bituminous coals in the South Wales coalfield IS as feed coals in power station boilers. Theoretically, the resultant concentration of most ESEs in the solid residues from power plant coal combustion can be alleviated by careful blending of feed coals with low and high ESE contents.
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00/03032 Investigation of lean high-ash coals in Ukraine for prospective preparation of metalized raw materials Ponomarev, L. L. 12~3.~‘~sslr. liclrehr~ Zrrr,cd.. C’ht,m Mercrll.. 1998. I I, 7l72. (In Russian) In this investigation, the lean coal samples containing 21-52% ash were considered for prospective gasification as fuel gases for metalizing of iron ore charge. The suitable lump coals contained 5 40% ash and 5 15% volatiles for the fuel value $ 10 MJikg. The charge containing concentrated iron ore and 20% coal was flred in a tunnel ful-nace heated with the fuel gas, resulting a metalization of 92%. 00/03033 Largest US plant gets larger Fiscor, S. Coal Age, 2000, 105, (4), 26-28 As CONSOL Energy endeavours to exploit the full potential of the world’s two largest longwall mines, the Bailey complex has had to implement a strategy for consistently growing capacity To unleash that potential production capacity, new large conveyor systems and bunkers were or will be installed underground. Mineral matter and trace elements in coals of the 00103034 Gunnedah Basin, New South Wales, Australia Ward, C. R. et ul. ht. J. Cvul Geol., 1999, 40. (4), 281-308. In this paper, the concentrations of major and trace inorganic elements in a succession of Permian coals from the Gunnedah Basin, New South Wales, have been determined by X-ray fluorescence techniques applied to both whole-coal and high-temperature ash samples. The results have been evaluated in the light of quantifiable data on the minerals in the same coals, determined from X-ray diffraction study of whole-coal samples using a Rietveld-based interpretation programme (Siroquant), to determine relationships of the trace elements in the coals to the mineral species present. Comparison of the chemical composition of the coal ash interpreted from the quantifiable mineralogical study to the actual ash composition determined by XRF analysis shows a high degree of consistency, confirming the validity of the XRD interpretations for the Gunnedah Basin materials. Quartz, illite and other minerals of detrital origin dominate the coals in the upper part of the sequence, whereas autlngenic kaolinite is abundant in coals from the lower part of the Permian succession. These minerals are all reduced in abundance, however, and pyrite is a dominant constituent, in coals formed under marine influence at several stratigraphic levels. Calcite and dolomite occur as cleat and fracture in-fillings, mostly in seams near the top and bottom of the sequence. The potassium-bearing minerals in the detrital fraction are associated with significant concentrations of rubidium, and the authigenic kaolinite with relatively high proportions of titanium. Zirconium is also abundant, with associated phosphorous and hafnium, in the Gunnedah Basin coal seams. Relationships exhibited by titanium, zirconium, neodymium and yttrium are consistent with derivation of the original sediment admixed with the seams from an acid volcanic source. Pyrite in the coals is associated with high concentrations of arsenic and minor proportions of thallium; no other element commonly associated with sulfides in coals, however, appears to occur in significant proportions with the pyrite in the sample suite. Small concentrations of chlorine present in the coal are inversely related to the pyrite content, and appear to represent ion-exchange components associated with the organic matter. Strontium and barium are strongly associated with the cleat-filling carbonate minerals. Germanium and gallium appear to be related to each other and to the coal organic matter. Chromium and vanadium tare also related to each other, as are cerium, lanthanum, neodymium and praeseodymium, but no relationship is shown by these to the organic matter or a particular mineral component. 00103035 Mineralogy and geochemistry of selected coal seams and their combustion residues from the Sydney area, Nova Scotia, Canada Mukhopadhyay, P. K. et (11. Int J. CM/ Gcol., 1999, 40, (2-3). 253-254 The miheralbgy and geochemistry of selected coal seams and their fly ashes from the Sydney area, Nova Scotia, Canada, are reviewed. 00103036 Modeling of the pyrolysis process of coal particles Gerasimov, G. Ya. J. Eng. Phy,s. Thermophys., 1999, 72, (2), 231-237. The development of a mathematical model of the pyrolysis of coal particles is presented. The model takes into conslcleration the transfer of heat from the particle to the surrounding medium, the kinetics of release of volatile components, the secondary reactions of cracking and the depositions of tar in its motion in the particle pores. Comparisons are made between the calculated results and the available experimental data. 00103037 Modes of occurrence of mercury in coals from Guizhou, China Feng, X. and Hong, Y. Furl, 1999, 78, (IO). 1181-1188. The modes of occurrence of mercury in coals from Guizhou, were investigated by using sequential extraction procedures and density separation experiments. The sequential extraction tests were carried out by using 32 coals sampled from the Longtan Group of the Permian system in Guizhou Province. Eight coal samples collected from the same area were divided into 10 density fractions between cl.4 and >2.8 g/cm3 by separation in a heavy liquid mixture. Combining the results of mineral transformation and of the amount of mercury leached during the leaching experiments with the results of the correlation between mercury and mineral phases and organic matter from density separation experiments,
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the authors concluded that mercury in the examined coals mainly exists in pyrite. Most of the mercury in these coals can be brought into the environment easily by acid mine drainage. A rather large part of mercury in coals from Guizhou may be removed by using conventional coal cleaning techniques. 00103038 Nature and mechanism of gas-permeable zones forming in coal seams Kuznetsov, S. V. Fi.-.-Tekh. Prohl. Razrcrh. Polrx Iskop., 1999, 1, 31-27. (In Russian) This paper describes the mechanism of forming and development of gaspermeable zones around mine workings and boreholes on the basis of results of in siru observations for the gas pressure change in coal seams and analysis of coal shrinkage and swelling during the sorption processes. The gas movement in coal seams can be considered as a filtration wave with the jump of adsorbed gas at the front coinciding with the moving boundary of gas-permeable zone. Hook’s law connecting the components of stresses and elastic deformations with allowance for the coal shrinkage and swelling during the sorption processes proceeding in the coal seams has been written out. 00/03039 Organic matter of coal and its transformations during pyrolysis Strugala, A. and Porada, S. Gospml. Suro~vcnmi Miner, 1999, IS, (I), 9-63. (In Polish) The most important contributions in the area of the chemical and physical properties of coals are reviewed. Particular emphasis is placed on hypotheses on the character of the coal structure unit and on two- and three-dimensional structural models of coal. Processes and chemical reactions taking place during carbonization are presented. This is followed by the compilation of the available polymeric models of the coal structure. Recent studies on coal as a two-component system are discussed, including such problems as the chemical structure of the molecular and macromolecular components, interactions between these two components, and chemical character and density of cross-linked bonds in the macromolecular framework. In the subsequent chapter, studies on coal as a colloidal system are described with the focus on changes in the coal’s colloidal structure during carbonization. Numerous investigations concerning the physical structure of coal and its changes during carbonization are also addressed. The review leads to the conclusion that the available structural models are not alternatives but that they are rather complementary to each other. By including both the chemical and physical approaches to the structure of the coals, it is possible to achieve a better understanding of many structural aspects and also a more realistic description of the coal’s behaviour during carbonization. 00103040 Petrographic and technological properties from the Raspadskaya Mine Zolotukhin, Y. A. Koks K/Tim, 1999, 4, S-l 1. (In Russian) The coking,properties of coals are discussed in this paper.
of coals
00/03041 Quality parameters of lignite of the North Bohemian Basin in the Czech Republic in comparison with the world average lignite Bouska, V. and Pesek, J. In!. J. Coral Geol., 1999, 40. (223), 21 l-235 Out of all the elements in atmospheric emissions and fallout from coal combustion sulfur is considered to be the most harmful. Total sulfur content (S,$) in lignites of the North Bohemian Basin (NBB) has a geometric mean of 1.61 wt% at n=12,979, and is mostly influenced by the presence of iron disulfides. The distribution of sulfur and many trace elements is log normal. A non-uniform distribution of sulfur in lignite was found within the basin, with the lowest Sd contents (i.e. not exceeding 1 wt% sulfur) confined to the eastern and south-eastern margin of the NBB. Contents between 1 and 1.5 wt% sulfur are most common in lignites of the south-central NBB. Lower sulfur contents were identified in the area of the Zatec delta and its northern extension. In contrast, high contents of sulfur in lignite (exceeding 1.5 wt%) are found along the northern margin of the basin at the foot of the Krusne hory mountains and in the westernmost part of the NBB. Three genetically different types of iron disulfides occur in lignite of the NBB - synsedimentary (early diagenetic), diagenetic, and epigenetic. Among those forms, synsedimentary disulfides (mostly pyrite) appear to be most abundant. They form finely dispersed microscopic framboids or veinlets that commonly parallel the coal bedding. The other iron disulfide forms are much less abundant. Dissolved sulfate which was supplied to the NBB during the Miocene is likely to have been derived from sulfides of the Krusne hory mountains crystalline complex. This unit has an isotopic composition of sulfide sulfur varying between -1 and +57!&. Consequently, the sulfate supplying the NBB should exhibit slightly positive 63‘S values. Syngenetic pyrites forming microframboids or veinlets in coal show 6?j values close to O%a. These values are similar to those of sulfur dioxide in gases of power stations burning NBB coal. This implies that during thermal oxidation of the dominant pyrite, no considerable shifts in sulfur isotopic composition occur. 00/03042 Rapid quality control for coal seams - by gamma ray transmission technique Sekhar, N. R. el al. Appl. Radiuirrr.Isor.. 1999, 51, (3). 269-272.
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Coal quality expressed as a useful heat value (UIIV) depends on various parameters such as fixed carbon, volatiles, ash and moisture. In this paper, these factors have been assessed and the detailed dependence of UHV on these parameters has been studied for samples of coal from a local mine. The samples were subjected to collimated low energy gamma beams and correlation was obtained between the attenuation coefficient and UHV. It is concluded that the method is reliable, fast, non-destructive and that it can be used to estimating UHV. 00/03043 Reactivity studies of Malaysian coals for clean energy systems Ismail, A.-F. and Mahdi, F. M. A. Enrrxy Environ.. Proc Truh:on In/. Energy E?tviron. .S.rmp., i,i( ’ /, 1999. 107-l IO. Edited by Dincer I and Ayhan T. The cost of transportation and the emissions from coal-fired power generators represent two major problems in using coals as an energy source. To overcome the emission problem, research in clean coal technology that includes mild gasification has been done. This paper presents the experimental results of reactivity studies of coal combustion as a part of research for clean coal technology. Using the TGA (thermogravimetric analyser) in a combustion laboratory, three types of Malaysian coals are investigated: Silantek, Mukah-Balingian, and Merit Pilla. The combustion parameters used are combustion temperature, oxygen atmosphere, combustion heating rate, and fluid velocity. The combustion processes are performed under mild gasification conditions. Various particle sizes of the coals are studied systematically. Proximate analysis shows that the Silantek coal contains the highest fix carbon while the Mukah-Balingian coal contains the lowest fix carbon. Silantek coal has the highest calorific value of 7317 Cal/g. The self-ignition phenomenon of each type of coals is discussed and it is found that the likelihood of ignition increases with combustion heating rate. 00/03044 Relation between variation of parameters and the softening and fusibility behaviors of coals during heating Takanohashi, T. e/ al. Teersu to Hugme, 1999, 85, (5), 382-386. (In Japanese) Geiseler plastometry, differential scanning calorimetry (DSC), proton magnetic resonance thermal analysis (PMRTA) and dynamic viscoelasticity were measured for high-caking Warkworth and low-caking K-Prima coals at a heating rate of 3”Cimin under nitrogen. The amount of solvent-soluble constituent of the coals heat-treated at 3”Cimin was also measured by using a solvent extraction with carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent at room temperature, which gives high extraction yields for the heattreated coals in the softening range. Changes in various chemical and physical parameters from the measurements were compared with one another to investigate the mechanism of softening and fusibility of coals. It is suggested that the softening occurs through a physical relaxation of aggregates m coal macromolecular structure and the amount of the solventsoluble constituents greatly increases, resulting in an enhancement of the softening and fusibility. The mobility parameter from PMRTA, the viscoelastic parameter and Geiseler fluidity gave the maximum at similar temperature, showing that fusibility is the result of increased mobility of whole coal. The dynamic viscoelastic measurement is a useful and convenient means for the study on caking behaviour of coals since it can estimate both the fluidity and the elasticity of coals concurrently. 00/03045 Rheological properties and model of the two-phase structure of coal Ulanovskii, M. L. Koks Khim, 1999, 3, 5-8. (In Russian) Two fluidity peaks in the temperature diagram of plasticity of some coals’ were observed. This sighting is in agreement with the current model of the two-phase structure of organic matter in coal. 00/03046 Role of coal type and rank on methane sorption characteristics, of Bowen Basin, Australia Laxminarayana, C. and Crosdale, P. J. In/. J. Cod Cd., 1999, 40. (4), 309325. Coal composition, particularly the organic fraction, has been investigated as to its effect on gas sorption for Bowen Basin and Sydney Basin, Australia. Maceral composition influences on gas retention and release were investigated by using iso-rank pairs of hand-picked bright and dull coal in the rank range of high volatile bituminous (0.78% R,, ,,,) to anthracite (3.01% R <, ,.,.). Adsorption isotherm results of dry coals indicated that Langmuir volume (V,) for bright and dull coal types followed discrete, second-order polynomial trends with increasing rank. Bright coals had a minimum VL at 1.72% R, m.lx, and dull coals had a minimum VL at 1.17% R,, ,,,itX.At low rank, Vt_ was greater in bright coal by about 10 ems/g, but as the rank increased, the bright and dull trends converged and crossed at 1.65% R, max. At ranks higher than 1.65% R,, mnx, both bright and dull coals followed similar trends. These competing trends mean that the importance of maceral composition on Vi_ varies according to rank. In high volatile bituminous coals, increases in vitrinite content are associated with increases in adsorption capacity. At ranks higher than medium to low volatile bituminous, changes in maceral composition may exert relatively little influence on adsorption capacity. The Langmuir pressure (P,) showed a strong relationship of decreasing PL with increasing rank, which was not related to coal type, It is suggested that the observed trend is related to a decrease in the heterogeneity of the pore surfaces, and subsequent increased coverage by the adsorbate, as coal rank increases. Desorption
00/03028 Electrical charge loss during pyrolysis of single coal particles Krammer, G. el crl. Fir<,/. 1999. 78, (IO), 1231-1235. Westerholt and Ibbenburen coal particles were devolatilized by means of a laser using an electrodynamic balance. The devolatilization occurred at ambient pressure and in a pure nitrogen atmosphere. The heating rate was moderate below 100 K/s. The particle temperature and the balancing voltage (to keep a single particle in the centre of the balance) were measured continuously. Parttcle size and shape, and the aerodynamic drag force were measured before and after the reaction. Charge loss of the reacted particle was determined and it was found to be proportional to weight loss, indicating that at least a fraction of the evolved devolatilization products can carry charge which seems only to be possible for high molecular weight products such as a condensed phase.
00103029 Gamma ash and moisture content indicator for coal analysis Kubicek, P. et 01.S/I. VedPr. Vys Sk Banskr-Tech. Univ. Ostrava, Rah Horn.-Geol., 1998, 44, (I). 47-53. (In Czech) This work examines the principle of combining absorption and scattering of low and medium energy gamma radiation in the determination of ash and moisture content of bituminous coal on conveyor belts. Both theoretical analysis and laboratory results obtained in the coal preparation plant are presented. An approximate determination of moisture content is possible provided that homogeneous material is carried by conveyor belt, the granulation of coal and its feed rate remain constant and the stability of scintillation detectors is sufficient. The accuracy of determination of moisture content of bituminous with maximum grain size coal of 50 mm (80% of less than 10 mm) was 1.9%.
00/03030 Gamma isotopic analysis of the coals and ashes from coal fired power plants of Turkey Akyuz, T. et al. C-rch. J. Phys., 1999, 49, 435-438. Gamma-isotopic analysis of the ashes produced by the combustion of lignite in power stations of Turkey together with the parent coal samples was performed with the aim to estimate its potential adverse impacts on human health. Gamma-isotopic analysfs indicated that all samples co:ta&d ZZ”Ra (coal samples: 89-14: Bq kg , ash samples: IS_;26 ,B,s kg ), U (coal ash samples: 9-33 pg g ), Th (coal samples: samples: 2-4 pg g 1-9 pg~ ‘; ash samples’: 8-12 pg g ‘), and 4(1K(coal samples: 26-67 Bq kg ‘; ash samples: not detected). However, ‘34Cs and 13’Cs were not found in the samples.
00103031 Impact of sulphur and trace element geochemistry on the utilization of a marine-influenced coal - case study from the South Wales Variscan foreland basin Gayer, R. A. et ul. Int. J. Coal Geol., 1999, 40, (2-3), 151-174. The analysis of incremental channel samples through two high volatile bituminous coal seams, the Amman Rider and Bute seams, below and above the Vanderbeckei Marine Band at the Westphalian A/B boundary, has been done using proximate petrography, inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and SEM with energy-dispersive X-ray (SEM-EDX) techniques, The results show that both coals are vitrinite-rich and indicate a similar history of paleomire development, with a period of falling water tables towards the middle plies of each seam. Mean sulfur contents in the coal with the marine roof, the Amman Rider seam (4.19 wt%) are almost four times higher than in the coal with a non-marine roof, the Bute seam (1.09 wt%), implying that high sulfur contents are derived from sea water sulfate. In both coals, sulfur is predominantly in the form of pyritic sulfur. Both syngenetic, framboidal and euhedral crystals, and epigenetic vein and cleat-fill pyrite are present. Relatively constant levels of organic sulfur at around 2% have been recorded in the Amman Rider seam. Sulfur levels in the basal and top plies of each seam are at least twice that of the ply with the lowest sulfur content in the seam, reflecting the stages in paleomire development most strongly influenced by sulfatecontaining waters. Thorium/uranium ratios are below 2.9 in the coal with a marine roof, the Amman Rider seam, indicating an enrichment of uranium from sea water, most marked at the top and bottom of the seam. The seam without a marine roof shows thorium/uranium ratios between 2.5 and 4.9, indicating mild marine enrichment of uranium. The concentrations of environmentally significant trace elements (ESEs) are correlated with either the ash or sulfur contents, or both. The correlation between sulfur and lead, arsenic, copper, nickel in the coal with a marine roof implies an origin of these ESEs from sea water and their mode of occurrence in sulfide minerals. Most ESEs in this coal are present at levels at least twice that of the global average in coals, the exceptions being lead and zinc which have concentrations less than half the global average. By contrast, the coal without a manne roof and with lower sulfur contents has most ESEs present at concentrations less than a third of the global average, the exceptions being nickel and copper. Diagenetic hydrothermal activity is documented ifi the middle ply of the coal with a marine roof. This hydrothermal system redistributed the sulfur, lead and arsenic in this ply. The principal utilization of bituminous coals in the South Wales coalfield IS as feed coals in power station boilers. Theoretically, the resultant concentration of most ESEs in the solid residues from power plant coal combustion can be alleviated by careful blending of feed coals with low and high ESE contents.
fuels (sources,
winning, properties)
00/03032 Investigation of lean high-ash coals in Ukraine for prospective preparation of metalized raw materials Ponomarev, L. L. 12~3.~‘~sslr. liclrehr~ Zrrr,cd.. C’ht,m Mercrll.. 1998. I I, 7l72. (In Russian) In this investigation, the lean coal samples containing 21-52% ash were considered for prospective gasification as fuel gases for metalizing of iron ore charge. The suitable lump coals contained 5 40% ash and 5 15% volatiles for the fuel value $ 10 MJikg. The charge containing concentrated iron ore and 20% coal was flred in a tunnel ful-nace heated with the fuel gas, resulting a metalization of 92%. 00/03033 Largest US plant gets larger Fiscor, S. Coal Age, 2000, 105, (4), 26-28 As CONSOL Energy endeavours to exploit the full potential of the world’s two largest longwall mines, the Bailey complex has had to implement a strategy for consistently growing capacity To unleash that potential production capacity, new large conveyor systems and bunkers were or will be installed underground. Mineral matter and trace elements in coals of the 00103034 Gunnedah Basin, New South Wales, Australia Ward, C. R. et ul. ht. J. Cvul Geol., 1999, 40. (4), 281-308. In this paper, the concentrations of major and trace inorganic elements in a succession of Permian coals from the Gunnedah Basin, New South Wales, have been determined by X-ray fluorescence techniques applied to both whole-coal and high-temperature ash samples. The results have been evaluated in the light of quantifiable data on the minerals in the same coals, determined from X-ray diffraction study of whole-coal samples using a Rietveld-based interpretation programme (Siroquant), to determine relationships of the trace elements in the coals to the mineral species present. Comparison of the chemical composition of the coal ash interpreted from the quantifiable mineralogical study to the actual ash composition determined by XRF analysis shows a high degree of consistency, confirming the validity of the XRD interpretations for the Gunnedah Basin materials. Quartz, illite and other minerals of detrital origin dominate the coals in the upper part of the sequence, whereas autlngenic kaolinite is abundant in coals from the lower part of the Permian succession. These minerals are all reduced in abundance, however, and pyrite is a dominant constituent, in coals formed under marine influence at several stratigraphic levels. Calcite and dolomite occur as cleat and fracture in-fillings, mostly in seams near the top and bottom of the sequence. The potassium-bearing minerals in the detrital fraction are associated with significant concentrations of rubidium, and the authigenic kaolinite with relatively high proportions of titanium. Zirconium is also abundant, with associated phosphorous and hafnium, in the Gunnedah Basin coal seams. Relationships exhibited by titanium, zirconium, neodymium and yttrium are consistent with derivation of the original sediment admixed with the seams from an acid volcanic source. Pyrite in the coals is associated with high concentrations of arsenic and minor proportions of thallium; no other element commonly associated with sulfides in coals, however, appears to occur in significant proportions with the pyrite in the sample suite. Small concentrations of chlorine present in the coal are inversely related to the pyrite content, and appear to represent ion-exchange components associated with the organic matter. Strontium and barium are strongly associated with the cleat-filling carbonate minerals. Germanium and gallium appear to be related to each other and to the coal organic matter. Chromium and vanadium tare also related to each other, as are cerium, lanthanum, neodymium and praeseodymium, but no relationship is shown by these to the organic matter or a particular mineral component. 00103035 Mineralogy and geochemistry of selected coal seams and their combustion residues from the Sydney area, Nova Scotia, Canada Mukhopadhyay, P. K. et (11. Int J. CM/ Gcol., 1999, 40, (2-3). 253-254 The miheralbgy and geochemistry of selected coal seams and their fly ashes from the Sydney area, Nova Scotia, Canada, are reviewed. 00103036 Modeling of the pyrolysis process of coal particles Gerasimov, G. Ya. J. Eng. Phy,s. Thermophys., 1999, 72, (2), 231-237. The development of a mathematical model of the pyrolysis of coal particles is presented. The model takes into conslcleration the transfer of heat from the particle to the surrounding medium, the kinetics of release of volatile components, the secondary reactions of cracking and the depositions of tar in its motion in the particle pores. Comparisons are made between the calculated results and the available experimental data. 00103037 Modes of occurrence of mercury in coals from Guizhou, China Feng, X. and Hong, Y. Furl, 1999, 78, (IO). 1181-1188. The modes of occurrence of mercury in coals from Guizhou, were investigated by using sequential extraction procedures and density separation experiments. The sequential extraction tests were carried out by using 32 coals sampled from the Longtan Group of the Permian system in Guizhou Province. Eight coal samples collected from the same area were divided into 10 density fractions between cl.4 and >2.8 g/cm3 by separation in a heavy liquid mixture. Combining the results of mineral transformation and of the amount of mercury leached during the leaching experiments with the results of the correlation between mercury and mineral phases and organic matter from density separation experiments,
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01 So/id fuels (sources, winning, properfies)
the authors concluded that mercury in the examined coals mainly exists in pyrite. Most of the mercury in these coals can be brought into the environment easily by acid mine drainage. A rather large part of mercury in coals from Guizhou may be removed by using conventional coal cleaning techniques. 00103038 Nature and mechanism of gas-permeable zones forming in coal seams Kuznetsov, S. V. Fi.-.-Tekh. Prohl. Razrcrh. Polrx Iskop., 1999, 1, 31-27. (In Russian) This paper describes the mechanism of forming and development of gaspermeable zones around mine workings and boreholes on the basis of results of in siru observations for the gas pressure change in coal seams and analysis of coal shrinkage and swelling during the sorption processes. The gas movement in coal seams can be considered as a filtration wave with the jump of adsorbed gas at the front coinciding with the moving boundary of gas-permeable zone. Hook’s law connecting the components of stresses and elastic deformations with allowance for the coal shrinkage and swelling during the sorption processes proceeding in the coal seams has been written out. 00/03039 Organic matter of coal and its transformations during pyrolysis Strugala, A. and Porada, S. Gospml. Suro~vcnmi Miner, 1999, IS, (I), 9-63. (In Polish) The most important contributions in the area of the chemical and physical properties of coals are reviewed. Particular emphasis is placed on hypotheses on the character of the coal structure unit and on two- and three-dimensional structural models of coal. Processes and chemical reactions taking place during carbonization are presented. This is followed by the compilation of the available polymeric models of the coal structure. Recent studies on coal as a two-component system are discussed, including such problems as the chemical structure of the molecular and macromolecular components, interactions between these two components, and chemical character and density of cross-linked bonds in the macromolecular framework. In the subsequent chapter, studies on coal as a colloidal system are described with the focus on changes in the coal’s colloidal structure during carbonization. Numerous investigations concerning the physical structure of coal and its changes during carbonization are also addressed. The review leads to the conclusion that the available structural models are not alternatives but that they are rather complementary to each other. By including both the chemical and physical approaches to the structure of the coals, it is possible to achieve a better understanding of many structural aspects and also a more realistic description of the coal’s behaviour during carbonization. 00103040 Petrographic and technological properties from the Raspadskaya Mine Zolotukhin, Y. A. Koks K/Tim, 1999, 4, S-l 1. (In Russian) The coking,properties of coals are discussed in this paper.
of coals
00/03041 Quality parameters of lignite of the North Bohemian Basin in the Czech Republic in comparison with the world average lignite Bouska, V. and Pesek, J. In!. J. Coral Geol., 1999, 40. (223), 21 l-235 Out of all the elements in atmospheric emissions and fallout from coal combustion sulfur is considered to be the most harmful. Total sulfur content (S,$) in lignites of the North Bohemian Basin (NBB) has a geometric mean of 1.61 wt% at n=12,979, and is mostly influenced by the presence of iron disulfides. The distribution of sulfur and many trace elements is log normal. A non-uniform distribution of sulfur in lignite was found within the basin, with the lowest Sd contents (i.e. not exceeding 1 wt% sulfur) confined to the eastern and south-eastern margin of the NBB. Contents between 1 and 1.5 wt% sulfur are most common in lignites of the south-central NBB. Lower sulfur contents were identified in the area of the Zatec delta and its northern extension. In contrast, high contents of sulfur in lignite (exceeding 1.5 wt%) are found along the northern margin of the basin at the foot of the Krusne hory mountains and in the westernmost part of the NBB. Three genetically different types of iron disulfides occur in lignite of the NBB - synsedimentary (early diagenetic), diagenetic, and epigenetic. Among those forms, synsedimentary disulfides (mostly pyrite) appear to be most abundant. They form finely dispersed microscopic framboids or veinlets that commonly parallel the coal bedding. The other iron disulfide forms are much less abundant. Dissolved sulfate which was supplied to the NBB during the Miocene is likely to have been derived from sulfides of the Krusne hory mountains crystalline complex. This unit has an isotopic composition of sulfide sulfur varying between -1 and +57!&. Consequently, the sulfate supplying the NBB should exhibit slightly positive 63‘S values. Syngenetic pyrites forming microframboids or veinlets in coal show 6?j values close to O%a. These values are similar to those of sulfur dioxide in gases of power stations burning NBB coal. This implies that during thermal oxidation of the dominant pyrite, no considerable shifts in sulfur isotopic composition occur. 00/03042 Rapid quality control for coal seams - by gamma ray transmission technique Sekhar, N. R. el al. Appl. Radiuirrr.Isor.. 1999, 51, (3). 269-272.
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Fuel and Energy Abstracts
November 2000
Coal quality expressed as a useful heat value (UIIV) depends on various parameters such as fixed carbon, volatiles, ash and moisture. In this paper, these factors have been assessed and the detailed dependence of UHV on these parameters has been studied for samples of coal from a local mine. The samples were subjected to collimated low energy gamma beams and correlation was obtained between the attenuation coefficient and UHV. It is concluded that the method is reliable, fast, non-destructive and that it can be used to estimating UHV. 00/03043 Reactivity studies of Malaysian coals for clean energy systems Ismail, A.-F. and Mahdi, F. M. A. Enrrxy Environ.. Proc Truh:on In/. Energy E?tviron. .S.rmp., i,i( ’ /, 1999. 107-l IO. Edited by Dincer I and Ayhan T. The cost of transportation and the emissions from coal-fired power generators represent two major problems in using coals as an energy source. To overcome the emission problem, research in clean coal technology that includes mild gasification has been done. This paper presents the experimental results of reactivity studies of coal combustion as a part of research for clean coal technology. Using the TGA (thermogravimetric analyser) in a combustion laboratory, three types of Malaysian coals are investigated: Silantek, Mukah-Balingian, and Merit Pilla. The combustion parameters used are combustion temperature, oxygen atmosphere, combustion heating rate, and fluid velocity. The combustion processes are performed under mild gasification conditions. Various particle sizes of the coals are studied systematically. Proximate analysis shows that the Silantek coal contains the highest fix carbon while the Mukah-Balingian coal contains the lowest fix carbon. Silantek coal has the highest calorific value of 7317 Cal/g. The self-ignition phenomenon of each type of coals is discussed and it is found that the likelihood of ignition increases with combustion heating rate. 00/03044 Relation between variation of parameters and the softening and fusibility behaviors of coals during heating Takanohashi, T. e/ al. Teersu to Hugme, 1999, 85, (5), 382-386. (In Japanese) Geiseler plastometry, differential scanning calorimetry (DSC), proton magnetic resonance thermal analysis (PMRTA) and dynamic viscoelasticity were measured for high-caking Warkworth and low-caking K-Prima coals at a heating rate of 3”Cimin under nitrogen. The amount of solvent-soluble constituent of the coals heat-treated at 3”Cimin was also measured by using a solvent extraction with carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent at room temperature, which gives high extraction yields for the heattreated coals in the softening range. Changes in various chemical and physical parameters from the measurements were compared with one another to investigate the mechanism of softening and fusibility of coals. It is suggested that the softening occurs through a physical relaxation of aggregates m coal macromolecular structure and the amount of the solventsoluble constituents greatly increases, resulting in an enhancement of the softening and fusibility. The mobility parameter from PMRTA, the viscoelastic parameter and Geiseler fluidity gave the maximum at similar temperature, showing that fusibility is the result of increased mobility of whole coal. The dynamic viscoelastic measurement is a useful and convenient means for the study on caking behaviour of coals since it can estimate both the fluidity and the elasticity of coals concurrently. 00/03045 Rheological properties and model of the two-phase structure of coal Ulanovskii, M. L. Koks Khim, 1999, 3, 5-8. (In Russian) Two fluidity peaks in the temperature diagram of plasticity of some coals’ were observed. This sighting is in agreement with the current model of the two-phase structure of organic matter in coal. 00/03046 Role of coal type and rank on methane sorption characteristics, of Bowen Basin, Australia Laxminarayana, C. and Crosdale, P. J. In/. J. Cod Cd., 1999, 40. (4), 309325. Coal composition, particularly the organic fraction, has been investigated as to its effect on gas sorption for Bowen Basin and Sydney Basin, Australia. Maceral composition influences on gas retention and release were investigated by using iso-rank pairs of hand-picked bright and dull coal in the rank range of high volatile bituminous (0.78% R,, ,,,) to anthracite (3.01% R <, ,.,.). Adsorption isotherm results of dry coals indicated that Langmuir volume (V,) for bright and dull coal types followed discrete, second-order polynomial trends with increasing rank. Bright coals had a minimum VL at 1.72% R, m.lx, and dull coals had a minimum VL at 1.17% R,, ,,,itX.At low rank, Vt_ was greater in bright coal by about 10 ems/g, but as the rank increased, the bright and dull trends converged and crossed at 1.65% R, max. At ranks higher than 1.65% R,, mnx, both bright and dull coals followed similar trends. These competing trends mean that the importance of maceral composition on Vi_ varies according to rank. In high volatile bituminous coals, increases in vitrinite content are associated with increases in adsorption capacity. At ranks higher than medium to low volatile bituminous, changes in maceral composition may exert relatively little influence on adsorption capacity. The Langmuir pressure (P,) showed a strong relationship of decreasing PL with increasing rank, which was not related to coal type, It is suggested that the observed trend is related to a decrease in the heterogeneity of the pore surfaces, and subsequent increased coverage by the adsorbate, as coal rank increases. Desorption