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00104 Use of surfactants to aid the dewatering of fine clean coal
0 1 Solid fuels (preparation) on the TGA sample pan and a filter sample collected between the TGA and FTIR and analysis gravimetrically by atomic absorption spectroscopy (AAS or inductively coupled argon plasma).
Use of an automated IR spectral method for determination of classtfication parameters of coals and charges in byproduct coking
99looO95
Zhilyaev, Y. A. et al. Koks Khim., 1998, (Z), 7-11. (In Russian) At a coking plant, an on-line IR analyser measures vitrinite reflectance, fusinite, volatiles, plastic layer thickness, and ash in coal feedstock for coking. 99lOOO96
The use of ultrasonic wave propagation parameters in the characterization of extracts from coals
Krzesinska, M. Fuel, 1998, 77, (6), 649-653. For the THF extract of Indian sub-bituminous Assay coal measurements were made of the velocities of longitudinal ultrasonic waves of frequency 2.5 MHz and selected parameters describing the coal extract structure, such as mean molar mass, aromaticity factor and concentration of unpaired spins. The sample of Assam coal (carbon content 80.4 wt%) was collected from the Gondwanaland deposits, where coals are very different from European Carboniferous coals. Results were compared with the data obtained for THF extracts from Polish coals of various rank (64.9-85.6 wt% carbon) and an Indian lignite (54.1 wt% carbon). Absolute temperature coefficients of ultrasonic velocity b and absolute concentration coefficients of ultrasonic velocity a were determined from ultrasonic measurements performed in solutions in THF for THF extracts of brown and bituminous Polish coals, Indian Neyeli lignite and sub-bituminous Assam coal, as well as in solutions in pyridine (PY) for PY extracts from Polish bituminous coals.
Verification of the linear relationship between carbon aromaticities and H/C ratios for bituminous coals
99iooo97
Maroto-Valer, M.et al. Fuel, 1998, 77, (7), 783-785. Carbon aromaticities for a further 15 bituminous coal samples, including vitrinite and semi-fusinite maceral concentrates, have been obtained by solid state ‘.‘C NMR using the quantifiably single-pulse excitation technique, to add to the results for samples reported previously. Between the aromatic@ (values in the range 0.73-0.91) and atomic H/C ratio holds for the new samples investigated, is a virtually identical linear correlation confirming that it is independent of both inertinite content and geological provincialism.
Preparation
agglomeration process. In addition to yielding clean coal with high recovery, this process requires significantly less oil concentration for agglomeration and produces stabler agglomerates than general oil agglomeration process, the cost of the oil would no longer be an important consideration for its commercial application. An important advantage of this process compared with other cleaning fine coal methods is that it can greatly reduce or eliminate the effects of coal degradation and some clay minerals on coal preparation. In this separation process, the natural hydrophobicity of the surface of coal particles and the addition of sodium oleate lead to a marked reduction of oil consumption. After conditioning by dispersant and surfactant in slurry, the anthracite and higher-rank bituminous coal particles tend to be more oleophilic and more easily agglomerated than lower-rank coals. Neutral diesel oil can be used to agglomerate oleophilic coals with good rejection of clay minerals at a little oil consumption, with agitation at 2000 rpm. 99/00101 A novel process for preparation of active carbon from sapropelitic coals Bodoev, N. V. et al. Fuel, 1998, 77, (6), 473-478. The preparation of active carbons starting from sapropelitic coals is the aim of this work. Firstly, a traditional route of manufacturing, coking and activation (820°C) was carried out. The specific area (BET) of the activated semicokes of six sapropelitic coal samples varied from two to about five hundred. Secondly, using Taimylir coal, a novel way of active carbon preparation was attempted combining low temperature modification and chemical activation. The modification was carried out using nitric acidacetic anhydride mixture at room temperature and tested by swelling and weight uptake measurements. The modified coal samples were analysed by TGA and FTIR spectroscopy. The chemical activation route included impregnation by an activator (KOH) and a subsequent heating (2 h under argon) at selected temperatures ranging from 300 to 900°C. Surface areas were detected by BET and SAKS methods.
99/00102 Preparation of activated carbon from bitumlnous coal wlth phosphoric acid activation Teng, H. et al. Carbon, 1998, 36, (9), 1387-1395. In this study activated carbons were prepared from an Australian bituminous coal. The preparation process consisted of phosphoric acid impregnation followed by carbonization in nitrogen at 400-6Oo”C for l-3 hours. The results show that the surface area and pore volume of the resulting carbons increase with the chemical ratio, HaPO&oal. The chemically activated carbon, prepared from carbonization at 500°C for 3 hours was found to have maximum surface area and pore volume values. Examined was the physical activation with CO2 of the initially H3P04 activated carbon and the results suggest that the combined activation is suitable for producing high porosity carbons with a high proportion of mesoporosity.
99100096
Cleaning of China high sulfur coals by selective dlspersion and flocculation
Wang, L. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (6), 35-38. In China, a process for removing pyritic sulfur from high sulfur coals by selective dispersion and flocculation has been conceptually developed and tested. The tentative tests on China high sulfur coals have shown that this coal cleaning process can be very efficient in coal desulfurization, provided the process parameters are properly optimized. While acquiring high coal recovery, the total sulfur rejection with four kinds of coals normally falls in the range 57 to 71% by one-step reverse flocculation, and within the range 40 to 59% by one-step normal flocculation process. For the removal of pyrite particles from coal fines suspensions, this cleaning process presents a promising approach.
influence of anthracite preparation of activated carbons
99lOOO99
pre-treatment
in
the
Daulan, C. et al. Fuel, 1998, 77, (6), 495-502. HCIO., was used prior to physical gasification with CO2 to produce activated carbon from La Mure (France) anthracite by chemical modification. BET surface areas as high as 1600 m* g-’ and a total pore volume of -1 cmJ gg’ were obtained for this activated carbon. At low temperature part of the chlorine had reacted with the anthracite producing partial oxidation. Contrary to all expectations, SEM images confirmed no exfoliation after thermal shock. The main effect of the chemical pretreatment is to reduce the time of physical activation. This reduction can be attributed to the creation of numerous channels in the anthracite macrotexture during chemical pre-treatment and thermal shock. The accessibility of the inner surface of the anthracite to CO2 was increased, and was responsible for deep gasification of the anthracite. Finally, a microporous carbon with a significant amount of mesoporosity caused mainly by physical activation after chemical pretreatment.
A new process degradation coal fines in water
99/00100
for
preparation
of
easy
Wang, L. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (6), 29-34. Using three Chinese coal samples of easy degradation coal fines in water, the sharp separation of ultrafine coal from slimes with the highest clay content ever attained has resulted from the application of a hydrophobic
On the role of oil wetting in the cleaning of high 99/00103 rank coals by agglomeration Garcia, A. B. et al. Fuel, 1998, 77, (5), 387-392. By measuring the oil/water/coal contact angle with heptane and with crude and refined vegetable oils the wettability of three Spanish anthracites with a large mineral matter content was studied. For this purpose the captive drop method was used. The contact angle depended on the coal, oil, and an interaction between coal and oil. Particle agglomeration tests were conducted to determine the maximum recovery of organic matter for each combination of coal and oil. The maximum recovery was observed to correlate well with the three-phase contact angle when heptane was employed as an agglomerant for the different anthracites. When vegetable oils were employed as agglomerants, the maximum recovery was also observed to correlate well with the contact angle in half the cases. For the other half the recovery exceeded what would have been predicted by the contact angle. Therefore, for these cases the oil wettability of the coal seemed greater under dynamic conditions than under static conditions.
99lOOlO4 clean coal
Use of surfactants to aid the dewatertng of fine
Singh, B. P. et al. Fuel, 1998, 77, (12), 1349-1356. Investigated was the vacuum filtration of clean coal slurries and flocculated slurries with cationic, anionic and nonionic surfactants. Significant reductions in filter cake moisture content were obtained for all types of surfactant. The most effective surfactant was CTAB. By using a moderate dosage of flocculant followed by surfactant pretreatment the final moisture content of filter cakes was reduced from 21 to 11.7 wt%. Measurements of electrophoretic mobility, surface tension, adsorption, dewatering kinetics and kinetics of adsorption of surfactants were also carried out. A direct correlation exists between the point of zero charge and residual moisture reduction in the filter cake. Test results show that surface tension by itself does not give much indication of the effectiveness of surfactants as dewatering agents. The enhancement in filtration dewatering characteristics has been attributed to the changes that surfactant adsorption causes in the wetting characteristics of the coal surface.
Fuel and Energy Abstracts January 1999
11
Use of an automated IR spectral method for determination of classtfication parameters of coals and charges in byproduct coking
99looO95
Zhilyaev, Y. A. et al. Koks Khim., 1998, (Z), 7-11. (In Russian) At a coking plant, an on-line IR analyser measures vitrinite reflectance, fusinite, volatiles, plastic layer thickness, and ash in coal feedstock for coking. 99lOOO96
The use of ultrasonic wave propagation parameters in the characterization of extracts from coals
Krzesinska, M. Fuel, 1998, 77, (6), 649-653. For the THF extract of Indian sub-bituminous Assay coal measurements were made of the velocities of longitudinal ultrasonic waves of frequency 2.5 MHz and selected parameters describing the coal extract structure, such as mean molar mass, aromaticity factor and concentration of unpaired spins. The sample of Assam coal (carbon content 80.4 wt%) was collected from the Gondwanaland deposits, where coals are very different from European Carboniferous coals. Results were compared with the data obtained for THF extracts from Polish coals of various rank (64.9-85.6 wt% carbon) and an Indian lignite (54.1 wt% carbon). Absolute temperature coefficients of ultrasonic velocity b and absolute concentration coefficients of ultrasonic velocity a were determined from ultrasonic measurements performed in solutions in THF for THF extracts of brown and bituminous Polish coals, Indian Neyeli lignite and sub-bituminous Assam coal, as well as in solutions in pyridine (PY) for PY extracts from Polish bituminous coals.
Verification of the linear relationship between carbon aromaticities and H/C ratios for bituminous coals
99iooo97
Maroto-Valer, M.et al. Fuel, 1998, 77, (7), 783-785. Carbon aromaticities for a further 15 bituminous coal samples, including vitrinite and semi-fusinite maceral concentrates, have been obtained by solid state ‘.‘C NMR using the quantifiably single-pulse excitation technique, to add to the results for samples reported previously. Between the aromatic@ (values in the range 0.73-0.91) and atomic H/C ratio holds for the new samples investigated, is a virtually identical linear correlation confirming that it is independent of both inertinite content and geological provincialism.
Preparation
agglomeration process. In addition to yielding clean coal with high recovery, this process requires significantly less oil concentration for agglomeration and produces stabler agglomerates than general oil agglomeration process, the cost of the oil would no longer be an important consideration for its commercial application. An important advantage of this process compared with other cleaning fine coal methods is that it can greatly reduce or eliminate the effects of coal degradation and some clay minerals on coal preparation. In this separation process, the natural hydrophobicity of the surface of coal particles and the addition of sodium oleate lead to a marked reduction of oil consumption. After conditioning by dispersant and surfactant in slurry, the anthracite and higher-rank bituminous coal particles tend to be more oleophilic and more easily agglomerated than lower-rank coals. Neutral diesel oil can be used to agglomerate oleophilic coals with good rejection of clay minerals at a little oil consumption, with agitation at 2000 rpm. 99/00101 A novel process for preparation of active carbon from sapropelitic coals Bodoev, N. V. et al. Fuel, 1998, 77, (6), 473-478. The preparation of active carbons starting from sapropelitic coals is the aim of this work. Firstly, a traditional route of manufacturing, coking and activation (820°C) was carried out. The specific area (BET) of the activated semicokes of six sapropelitic coal samples varied from two to about five hundred. Secondly, using Taimylir coal, a novel way of active carbon preparation was attempted combining low temperature modification and chemical activation. The modification was carried out using nitric acidacetic anhydride mixture at room temperature and tested by swelling and weight uptake measurements. The modified coal samples were analysed by TGA and FTIR spectroscopy. The chemical activation route included impregnation by an activator (KOH) and a subsequent heating (2 h under argon) at selected temperatures ranging from 300 to 900°C. Surface areas were detected by BET and SAKS methods.
99/00102 Preparation of activated carbon from bitumlnous coal wlth phosphoric acid activation Teng, H. et al. Carbon, 1998, 36, (9), 1387-1395. In this study activated carbons were prepared from an Australian bituminous coal. The preparation process consisted of phosphoric acid impregnation followed by carbonization in nitrogen at 400-6Oo”C for l-3 hours. The results show that the surface area and pore volume of the resulting carbons increase with the chemical ratio, HaPO&oal. The chemically activated carbon, prepared from carbonization at 500°C for 3 hours was found to have maximum surface area and pore volume values. Examined was the physical activation with CO2 of the initially H3P04 activated carbon and the results suggest that the combined activation is suitable for producing high porosity carbons with a high proportion of mesoporosity.
99100096
Cleaning of China high sulfur coals by selective dlspersion and flocculation
Wang, L. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (6), 35-38. In China, a process for removing pyritic sulfur from high sulfur coals by selective dispersion and flocculation has been conceptually developed and tested. The tentative tests on China high sulfur coals have shown that this coal cleaning process can be very efficient in coal desulfurization, provided the process parameters are properly optimized. While acquiring high coal recovery, the total sulfur rejection with four kinds of coals normally falls in the range 57 to 71% by one-step reverse flocculation, and within the range 40 to 59% by one-step normal flocculation process. For the removal of pyrite particles from coal fines suspensions, this cleaning process presents a promising approach.
influence of anthracite preparation of activated carbons
99lOOO99
pre-treatment
in
the
Daulan, C. et al. Fuel, 1998, 77, (6), 495-502. HCIO., was used prior to physical gasification with CO2 to produce activated carbon from La Mure (France) anthracite by chemical modification. BET surface areas as high as 1600 m* g-’ and a total pore volume of -1 cmJ gg’ were obtained for this activated carbon. At low temperature part of the chlorine had reacted with the anthracite producing partial oxidation. Contrary to all expectations, SEM images confirmed no exfoliation after thermal shock. The main effect of the chemical pretreatment is to reduce the time of physical activation. This reduction can be attributed to the creation of numerous channels in the anthracite macrotexture during chemical pre-treatment and thermal shock. The accessibility of the inner surface of the anthracite to CO2 was increased, and was responsible for deep gasification of the anthracite. Finally, a microporous carbon with a significant amount of mesoporosity caused mainly by physical activation after chemical pretreatment.
A new process degradation coal fines in water
99/00100
for
preparation
of
easy
Wang, L. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (6), 29-34. Using three Chinese coal samples of easy degradation coal fines in water, the sharp separation of ultrafine coal from slimes with the highest clay content ever attained has resulted from the application of a hydrophobic
On the role of oil wetting in the cleaning of high 99/00103 rank coals by agglomeration Garcia, A. B. et al. Fuel, 1998, 77, (5), 387-392. By measuring the oil/water/coal contact angle with heptane and with crude and refined vegetable oils the wettability of three Spanish anthracites with a large mineral matter content was studied. For this purpose the captive drop method was used. The contact angle depended on the coal, oil, and an interaction between coal and oil. Particle agglomeration tests were conducted to determine the maximum recovery of organic matter for each combination of coal and oil. The maximum recovery was observed to correlate well with the three-phase contact angle when heptane was employed as an agglomerant for the different anthracites. When vegetable oils were employed as agglomerants, the maximum recovery was also observed to correlate well with the contact angle in half the cases. For the other half the recovery exceeded what would have been predicted by the contact angle. Therefore, for these cases the oil wettability of the coal seemed greater under dynamic conditions than under static conditions.
99lOOlO4 clean coal
Use of surfactants to aid the dewatertng of fine
Singh, B. P. et al. Fuel, 1998, 77, (12), 1349-1356. Investigated was the vacuum filtration of clean coal slurries and flocculated slurries with cationic, anionic and nonionic surfactants. Significant reductions in filter cake moisture content were obtained for all types of surfactant. The most effective surfactant was CTAB. By using a moderate dosage of flocculant followed by surfactant pretreatment the final moisture content of filter cakes was reduced from 21 to 11.7 wt%. Measurements of electrophoretic mobility, surface tension, adsorption, dewatering kinetics and kinetics of adsorption of surfactants were also carried out. A direct correlation exists between the point of zero charge and residual moisture reduction in the filter cake. Test results show that surface tension by itself does not give much indication of the effectiveness of surfactants as dewatering agents. The enhancement in filtration dewatering characteristics has been attributed to the changes that surfactant adsorption causes in the wetting characteristics of the coal surface.
Fuel and Energy Abstracts January 1999
11