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03522 Hyperbaric filtration of fine clean coal slurries
01
Solid fuels (transpoti,
storage)
applied. The estimated enthalpy change was compared with the total enthalpy change estimated by DSC measurements to examine the importance of hydrogen bonding during the desorption of water. The enthalpy decreases with the progress of desorption. The paper clarifies the importance of the rearrangement of hydrogen bondings and the entropy effect. Evaluation of hyperbaric filtration for fine coal 98103518 dewatering: part 2. Effects of chemical addition Sung, D. J. et al. Ah. Fib. Sep. Technol., 1997, 11, 480-488. For application in the dewatering of fine coal cleaned by froth flotation, hyperbaric filtration with chemical additives was evaluated at laboratoryscale. The effects of addition of flocculants, surfactants and metal ions on final moisture content of the filter cakes were determined. The investigations included determination of the rates of filtration and dewatering, assessment of the effects of type of additive, establishment of optimum dosage of additives and examination of surface chemical properties of the coal with and without presence of additives. The synergistic effect of metal ion and surfactant addition were used to lower the moisture of clean coal in the study. Additives improved the filtration and dewatering behaviour of the fine coal slurries and an optimum dosage for all surfactants and flocculants yielding most rapid filtration and dewatering and/or minimum final cake moisture content was discovered. Cationic surfactants and anionic flocculating additives were found to be most effective in enhancing filtration. With presence of metal ions, the filter cake moisture lowered in the region of PZC, but the reduction of moisture content was not found to be considerable. Flotation of oil-agglomerated coal for ash and 98103519 pyrite removal-simultaneous grinding and agglomeration Trass, 0. Can. Pat. Appl. CA 2,172,028 (Cl. B03D1/006), 19 Sep 1997, Appl. 2,172,028, 18 Mar 1996, 19 pp. Fine coal beneficiation by oil agglomeration is an excellent technique, but a high level of oil is necessary for the separation of the spherical agglomerates by screening. When the subsequent separation is done by flotation, this disadvantage is eliminated. Better pyrite removal is also possible. In this application, such fine coal beneficiation process, also called hydrophobic flocculation-flotation (HFF), is described. It features low nonpolar oil consumption, intensive mechanical energy input, and smaller agglomerates or looser floes. This process can be simplified by grinding the coal in water with the addition of small amounts of oil. The excess grinding energy is then used for 13.3% ash and 3.3% total sulfur, 1.4% pyritic. After four stages of flotation, ash and pyrite removal were 93% and 66%, respectively, with 87% combustibles recovery. The parameters affecting the HFF process, such as particle size, dosage of non-polar oil, pH value of the slurry and duration of agitation, were studied. Simultaneous grinding and agglomeration (SGA) using the Szego Mill is also described using very low levels of oil. The intensive agitation/preconditioning step prior to flotation was eliminated. When the other parameters established from the sequential process were used with the slightly lower combustibles recovery. With the SGA process, significant equipment simplification and energy savings are possible. Heteroatom removal from fossil fuels: the BIOCAT/ 98lo3520 CHEMCAT approach Mahajan, D. ef al. Prepr. Am. Chem. Sot., Div. Pet. Chem., 1998, 43, (1). 99-180. Bioconversion of a heavy petroleum in the presence of a biocatalyst followed by catalytic chemical treatment (BIOCAT/CHEMCAT approach) removes heteroatoms to a very low level and upgrades it. High-temperature desulfurization of fossil fuels by 98103521 microbes Konishi, H. et al. Jpn. Kokai Tokkyo Koho JP 10 36,859 [98 36,8591 (Cl. ClOG32/00), 10 Feb 1998, Appl. 96/200,696, 30 Jul 1996, 15 pp. (In Japanese) Organic sulfur compounds are decomposed by microbes belonging to Paenibacillus. The process is especially suitable for removing heterocyclic sulfur compounds from petroleum and coals. Hyperbaric filtration of fine clean coal slurries 98lo3522 Yang, J. and Parekh, B. K. Fluid/Parr. Separate J., 1997, 10, (3), 218-224. Two clean coal slurries were subjected to laboratory dewatering studies. The first slurry was composed of Pittsburgh No. 8, containing 25 wt% solids of which 78 wt% were retained on 200 mesh sieve, and the second of Pocahontas No. 3, containing 11 wt% solids of which only 33 wt% were retained on 200 mesh sieve. Vacuum filtration was not effective for dewatering of Pittsburgh coal. High pressure dewatering studies were conducted using a known mass of slurry and varying air pressure from 40 to 80 psi (2.7 to 5.5 bar). The optimum dewatering conditions for the Pittsburgh coal slurry in obtaining a filter cake with 24% moisture, employing 70 psig (4.8 bar) pressure, with a mass loading of 4.97 lb/f? (24.3 kg/m*) which yielded a cake thickness of 1.5 cm. For the Pocahontas slurry, in obtaining a filter cake with 11.5% moisture, employing 80 psig (5.6 bar) pressure, with a mass loading of 4.0 lb/ft* (19.6 Kg/m*) which yielded a cake thickness of 1.4 cm. A correlation was found between the residual moisture content and pressure, when pressure is expressed as the pressure gradient.
334
Fuel and Energy Abstracts
September
1998
98103523 Improving the vacuum filtration of fine coal using simultaneous dewatering and size enlargement Veal, C. J. Adv. Filtr. Sep. Technol., 1997, 11, 541-546. For addition to fine-coal feeds in a vacuum filter unit, to enhance simultaneous dewatering and size enlargement, binders were investigated. The effects required by the binders are moisture content reduction of the filter cakes and/or increasing their mechanical strength. Two preferred additives were identified: (1) binder X, a styrene-acrylate copolymer, and (2) binder Y, a heavy fuel oil emulsion. Binder X was extremely effective at increasing the strength of coal filter cakes both in the wet and dry states, and also rendered the cake highly resistant to breakdown in water. Binder Y reduced filter cake moisture by 7-8 wt%. Neither achieved both cake strengthening and moisture reduction, the results were considered sufficient to warrant further research. 98103524 Investigation of virgin coals and coals subjected to a mild acid treatment Clark, T. M. et al. Hypetjine Interact., 1998 (Pub. 1997) 112, (l-4, Industrial Applications of the Moessbauer Effect, Pt. 2) 227-230. The relative marcasite/pyrite contents in virgin coals can be determined by means of “Fe Mossbauer spectroscopy. However, the presence of ironcontaining silicates, carbonates, or other salts causes complications. The application of a mild chemical treatment involving hydrofluoric acid has been employed to remove these iron-containing phases while leaving the iron-disulfide phases unaffected. Several South African coal samples with non-iron disulfide, iron-containing phases ranging from 18 to 30 wt% have been subjected to a hydrofluoric acid leaching at room temperature. The loss of mineral matter with HF leaching correlates well with the mineral matter residue following low temperature ashing. The “Fe Mossbauer spectra of the resulting coal samples, collected at 297 K, indicate that only Fe& phases are present. The Mossbauer parameters for these samples indicate the absence of appreciable quantities of marcasite in the coals.
Modification of brown coal by methanol 98lo3525 Zherebtsev, S. I. Khim. Tverd. Topl., 1997, (4). 32-34. (In Russian) An 8-15 fold increase in the yields of brown coal extraction with methanol, hexane or alcohol-benzene is possible after alkylation with methanol. Structural modification of coking coal during nitra98103528 tion Kucherenko, V. A. et al. Khim. Tverd. Topl., 1997, (4), 12-20. (In Russian) During nitration of a coking coal with nitric acid-acetanhydride or trifluoroacetaldehyde for
Transport, Storage 98lO3528 Effect of temperature-dependent changes of the specific surface area of coal on the kinetics of the adsorptionreaction process of its heterogeneous oxidation Pashkovskii, P. S. et al. Khim. Tverd. Topl., 1998, (1) 59-66. (In Russian) Oxygen chemisorption kinetics on coal were studied when changes in coal specific surface area are temperature dependent at 320-580 K. This study is relevant to coal spontaneous combustion caused by self-heating during storage. Shiploader ready for coal export expansion 98lo3529 Anon. Queensland Coal, 1998, 4, (3), 48. Built at Brisbane’s Keppel Cairncross shipyard, a $20 million coal shiploader has a capacity of 1000 t and is needed to service Brisbane’s growing coal export industry. With a throughput of up to 8650 t/h, the coal shiploader is one of Australia’s fastest and most efficient. This will enhance Queensland’s competitiveness in the export industry.
Solid fuels (transpoti,
storage)
applied. The estimated enthalpy change was compared with the total enthalpy change estimated by DSC measurements to examine the importance of hydrogen bonding during the desorption of water. The enthalpy decreases with the progress of desorption. The paper clarifies the importance of the rearrangement of hydrogen bondings and the entropy effect. Evaluation of hyperbaric filtration for fine coal 98103518 dewatering: part 2. Effects of chemical addition Sung, D. J. et al. Ah. Fib. Sep. Technol., 1997, 11, 480-488. For application in the dewatering of fine coal cleaned by froth flotation, hyperbaric filtration with chemical additives was evaluated at laboratoryscale. The effects of addition of flocculants, surfactants and metal ions on final moisture content of the filter cakes were determined. The investigations included determination of the rates of filtration and dewatering, assessment of the effects of type of additive, establishment of optimum dosage of additives and examination of surface chemical properties of the coal with and without presence of additives. The synergistic effect of metal ion and surfactant addition were used to lower the moisture of clean coal in the study. Additives improved the filtration and dewatering behaviour of the fine coal slurries and an optimum dosage for all surfactants and flocculants yielding most rapid filtration and dewatering and/or minimum final cake moisture content was discovered. Cationic surfactants and anionic flocculating additives were found to be most effective in enhancing filtration. With presence of metal ions, the filter cake moisture lowered in the region of PZC, but the reduction of moisture content was not found to be considerable. Flotation of oil-agglomerated coal for ash and 98103519 pyrite removal-simultaneous grinding and agglomeration Trass, 0. Can. Pat. Appl. CA 2,172,028 (Cl. B03D1/006), 19 Sep 1997, Appl. 2,172,028, 18 Mar 1996, 19 pp. Fine coal beneficiation by oil agglomeration is an excellent technique, but a high level of oil is necessary for the separation of the spherical agglomerates by screening. When the subsequent separation is done by flotation, this disadvantage is eliminated. Better pyrite removal is also possible. In this application, such fine coal beneficiation process, also called hydrophobic flocculation-flotation (HFF), is described. It features low nonpolar oil consumption, intensive mechanical energy input, and smaller agglomerates or looser floes. This process can be simplified by grinding the coal in water with the addition of small amounts of oil. The excess grinding energy is then used for 13.3% ash and 3.3% total sulfur, 1.4% pyritic. After four stages of flotation, ash and pyrite removal were 93% and 66%, respectively, with 87% combustibles recovery. The parameters affecting the HFF process, such as particle size, dosage of non-polar oil, pH value of the slurry and duration of agitation, were studied. Simultaneous grinding and agglomeration (SGA) using the Szego Mill is also described using very low levels of oil. The intensive agitation/preconditioning step prior to flotation was eliminated. When the other parameters established from the sequential process were used with the slightly lower combustibles recovery. With the SGA process, significant equipment simplification and energy savings are possible. Heteroatom removal from fossil fuels: the BIOCAT/ 98lo3520 CHEMCAT approach Mahajan, D. ef al. Prepr. Am. Chem. Sot., Div. Pet. Chem., 1998, 43, (1). 99-180. Bioconversion of a heavy petroleum in the presence of a biocatalyst followed by catalytic chemical treatment (BIOCAT/CHEMCAT approach) removes heteroatoms to a very low level and upgrades it. High-temperature desulfurization of fossil fuels by 98103521 microbes Konishi, H. et al. Jpn. Kokai Tokkyo Koho JP 10 36,859 [98 36,8591 (Cl. ClOG32/00), 10 Feb 1998, Appl. 96/200,696, 30 Jul 1996, 15 pp. (In Japanese) Organic sulfur compounds are decomposed by microbes belonging to Paenibacillus. The process is especially suitable for removing heterocyclic sulfur compounds from petroleum and coals. Hyperbaric filtration of fine clean coal slurries 98lo3522 Yang, J. and Parekh, B. K. Fluid/Parr. Separate J., 1997, 10, (3), 218-224. Two clean coal slurries were subjected to laboratory dewatering studies. The first slurry was composed of Pittsburgh No. 8, containing 25 wt% solids of which 78 wt% were retained on 200 mesh sieve, and the second of Pocahontas No. 3, containing 11 wt% solids of which only 33 wt% were retained on 200 mesh sieve. Vacuum filtration was not effective for dewatering of Pittsburgh coal. High pressure dewatering studies were conducted using a known mass of slurry and varying air pressure from 40 to 80 psi (2.7 to 5.5 bar). The optimum dewatering conditions for the Pittsburgh coal slurry in obtaining a filter cake with 24% moisture, employing 70 psig (4.8 bar) pressure, with a mass loading of 4.97 lb/f? (24.3 kg/m*) which yielded a cake thickness of 1.5 cm. For the Pocahontas slurry, in obtaining a filter cake with 11.5% moisture, employing 80 psig (5.6 bar) pressure, with a mass loading of 4.0 lb/ft* (19.6 Kg/m*) which yielded a cake thickness of 1.4 cm. A correlation was found between the residual moisture content and pressure, when pressure is expressed as the pressure gradient.
334
Fuel and Energy Abstracts
September
1998
98103523 Improving the vacuum filtration of fine coal using simultaneous dewatering and size enlargement Veal, C. J. Adv. Filtr. Sep. Technol., 1997, 11, 541-546. For addition to fine-coal feeds in a vacuum filter unit, to enhance simultaneous dewatering and size enlargement, binders were investigated. The effects required by the binders are moisture content reduction of the filter cakes and/or increasing their mechanical strength. Two preferred additives were identified: (1) binder X, a styrene-acrylate copolymer, and (2) binder Y, a heavy fuel oil emulsion. Binder X was extremely effective at increasing the strength of coal filter cakes both in the wet and dry states, and also rendered the cake highly resistant to breakdown in water. Binder Y reduced filter cake moisture by 7-8 wt%. Neither achieved both cake strengthening and moisture reduction, the results were considered sufficient to warrant further research. 98103524 Investigation of virgin coals and coals subjected to a mild acid treatment Clark, T. M. et al. Hypetjine Interact., 1998 (Pub. 1997) 112, (l-4, Industrial Applications of the Moessbauer Effect, Pt. 2) 227-230. The relative marcasite/pyrite contents in virgin coals can be determined by means of “Fe Mossbauer spectroscopy. However, the presence of ironcontaining silicates, carbonates, or other salts causes complications. The application of a mild chemical treatment involving hydrofluoric acid has been employed to remove these iron-containing phases while leaving the iron-disulfide phases unaffected. Several South African coal samples with non-iron disulfide, iron-containing phases ranging from 18 to 30 wt% have been subjected to a hydrofluoric acid leaching at room temperature. The loss of mineral matter with HF leaching correlates well with the mineral matter residue following low temperature ashing. The “Fe Mossbauer spectra of the resulting coal samples, collected at 297 K, indicate that only Fe& phases are present. The Mossbauer parameters for these samples indicate the absence of appreciable quantities of marcasite in the coals.
Modification of brown coal by methanol 98lo3525 Zherebtsev, S. I. Khim. Tverd. Topl., 1997, (4). 32-34. (In Russian) An 8-15 fold increase in the yields of brown coal extraction with methanol, hexane or alcohol-benzene is possible after alkylation with methanol. Structural modification of coking coal during nitra98103528 tion Kucherenko, V. A. et al. Khim. Tverd. Topl., 1997, (4), 12-20. (In Russian) During nitration of a coking coal with nitric acid-acetanhydride or trifluoroacetaldehyde for
Transport, Storage 98lO3528 Effect of temperature-dependent changes of the specific surface area of coal on the kinetics of the adsorptionreaction process of its heterogeneous oxidation Pashkovskii, P. S. et al. Khim. Tverd. Topl., 1998, (1) 59-66. (In Russian) Oxygen chemisorption kinetics on coal were studied when changes in coal specific surface area are temperature dependent at 320-580 K. This study is relevant to coal spontaneous combustion caused by self-heating during storage. Shiploader ready for coal export expansion 98lo3529 Anon. Queensland Coal, 1998, 4, (3), 48. Built at Brisbane’s Keppel Cairncross shipyard, a $20 million coal shiploader has a capacity of 1000 t and is needed to service Brisbane’s growing coal export industry. With a throughput of up to 8650 t/h, the coal shiploader is one of Australia’s fastest and most efficient. This will enhance Queensland’s competitiveness in the export industry.