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01620 Enhanced column flotation performance for fine coal cleaning
07
97101606
Capacity
of high-pressure
grinding
rolls
Austin. L. G. er al. Trrrjrv. Sec. Mitl., Metall., Eqdor.. 1995, (Puh. 1996). 29X. hS-73iSection 3 Tests were carried out on six US coals and a crystallized quartz in an instrumented laboratory high-pressure grinding rolls machine equipped with IOO-mm-diameter rolls. As expected, the specific capacity decreased with increased grinding pressure for each material tested. There were significant differences among the six coals in the critical angle of nip, the effective feed porosity and the variation of strain at the gap relative to the grinding pressure. Although a precise correlation was not ohtained. the overall effect of these factors was that, at a given grinding pressure, the specific capactty increased as the Hardgrove grindability index of the coal increased.
97101609
Classifier
mills for coal grinding
and drying
Galk. J. and Peukrrt. W. Pro<. A?lnrr. Il~r. Pirtshurgh Coal Cortf., 1995, 12, 567-512. A special air classtfier mill for coal grinding is presented in this report. Air classifier mills use the two fundamental process steps grinding and classifying in one machine. In this report an air classifier mill, come typical process data as particle \ize distrihutions, possible throughput and an industrial application are shown.
97/01610 cleaning
Coal agloflotation: of town gas soils
a remediation
technique
for
Joshi. M. M. and Let. S. J. Hnzarl/. M~rrcr., 1906, 49. (2-3), 155-163. The present study investigates the use of a hydrophobic coal surface for the adsorption and removal of oily/tarry contaminants such as PAHs from town gas soils. The agloflotation process uses a coal-soil-water mixture to achieve simultaneous removal of mineral matter from coal. The coheneficiation achieves YOr/, and higher decontamination for soil and 40% and higher ash removal from coal.
Coal hydrogenation 97101611 catalyst (MOOS-Ni0/A1203) ‘waste’
catalysis
using
industrial
Wang, R. et al. Fuel. 1996, 75, (14). 1671-1675. A commercial MoQ?-NiO/A1207 (Akzo 153) catalyst used in a coal-liquid upgrading process for 400 h. to promote low-severity coal hydrogenation was investigated. Such a reaction system is considered to he economical. A tubing homh microreactor (25 cm” capacity) was used for dissolution reactions of a low-rank British bituminous coal in an industrial recycle solvent under various conditions. Results show that this catalyst ‘waste’ exerts considerable influence on the coal hydrogenation reactions compared with a fresh sulfided catalyst of the same type. This research has also improved understanding of the catalysed coal hydrogenation mechanisms and identified a potentially beneficial method of disposal of industrial catalyst wastes.
97101612 tion
Composition
and method
for inhibiting
coal oxida-
Roe. D. C. Can. Pat. Appl. CA 2,165,494 (Cl. CO9K3100). 21 Jul 1996. US Appl. 376.317. 20 Jan 1995; 20 pp. The paper describes composition and a method for inhibiting coal oxidation. Coal oxidation is inhibited by applying an aqueous solution of cationic polymer. e.g. adipic acid-diethylenetriamine-epichlorohydrin copolymer or aminomethylated polyacrylamide, to coal surfaces which are exposed to air. The compositions are preferably applied to coal as foams.
97101613 Demineralization of a bituminous flotation before obtaining activated carbons
coal
by froth
Rivera-Utrilla, J. et ul. Carbon, 1996, 34, (7), 917-921. Demineralization of a Spanish bituminous coal by froth flotation was carried out. The effect of the particle size, solution pH, and the presence of electrolytes on the process yield was investigated. Three activated carbon samples were obtained by steam activation of the floated coal. These activated carbons were texturally characterized using of N?, CO: and benzene adsorption. The results obtained with these three adsorptives are very similar, which indicates that the microporosity of the activated carbon samples is accesaihle to the molecules of the above compounds.
97101614 classifier.
The
design
of a three-product
mechanical
spiral
Korsak, L. L. and Tokareva. I. S. Koks Khim. 1995, (h), 29-31. (In Russian) The performance is studied of three-product mechanical spiral classifier with vortex generator and conical packings that create a centrifugal pulp stream at the lower section of a bath. The spiral classifier can he used for the concentration of coal slurries before feeding to the jigging machine.
Determination of the real lower limit 97101615 particles separation in the Reichert spiral separator
of
coal
Sweierkot-Kopala, et ul. Zesz. Nauk. P&tech. S/ask., Gorrl., .1995, 22.5. 263-283. (In Polish) A study on the determination of the lower limit of coal particle size in the Reichert spiral separator of the LD 4 type. Experiments were carried out with the coal particle size of 0.3-0.0, 0.5-0.0, and 1.0-0.0 mm. The feed was prepared in two versions: (I) simplified: and (2) using the whole fraction. It
Solid fuels (preparation)
was found that the lower limit of particles to he separated was 0.04.5 mm. if the particle size of the charge was < 1 mm. This result is hetter than that specified by the manufacturer (i.e. 0.075 mm).
97101616 pressure
Devolatilization
of
large
coal
particles
at high
Eatough, C. N. and Smoot, L. D. F‘uel, 1996, 75. (13). IhOl-1605. Experiments were carried out to measure the devolatilization times of large (0.1 and 0.2 g) Utah high-volatile bituminous B (hvBh) and North Dakota lignite coal particles in the 15-30 s range in air at IO1 and 507 kPa and air temperature 9tlO and 1200 K in a convective flow reactor. Visual observations indicated infrequent heterogeneous ignition of the lignite prior to devolatilization and occasional explosion of hituminous coal particles during devolatilization. Devolatilization times were correlated with temperature, pressure and particle.
97101617 DRIFT spectroscopic characterization ples modified by chemical treatments
of coal sam-
Nosyrev, I. E. ef ul. Fuel. 1996, 75. ( 13). 1549-l 5Sh. Diffusion reflectance IR spectroscopy was employed to characterize the modifications afforded hy several chemical treatments to the main functional groups of a hituminous coal. The starting materials were the polyanions and potassium coal adducts obtained from the parent coal. treated with potassium according to the Sternherg and Lazarov reactions. The results show the differences in the reactive sites involved in theqe reactions and those in the hehaviour of these sites during protonation or alkylation. Taking into account the semiquantttative result\ of the IR analysis, the participation of several active sites in the total hydrogen transfer was estimated. indicating the role of quinonic. aromatic and alkyl groups.
97101616 Effect of molecular weight of polyethylene frothers on their performance in low rank coal flotation
glycol
Saleh, A. M. and Iskra, J. Fizyhochun. Prohl. M/neralrrrgii. 1996, 30. 33-40. A study was conducted to explore the effect ot the molecular weight of polyethylene glycol frothers on flotation of low-rank coal. Four frothers of molecular weights of 400. 600. 1000, and 1500 were tested (e.g. PG 400. PG 600, PG 1000, and PG 1500. respectively). Polyethylene glycol of molecular weight 1000 gave the worst results. The best performance (i.e. high flotation recovery, rate, and selectivity) was observed for PG 600, whereas PG 400 performed worse than PG 600 and hetter than PG 1000 and PG 1500. The better performance of PG 600 was attrihuted to its greater surface activity.
97101619 floatability
Effect of the intensity of aeration air on distribution in batch coal flotation experiments
the
Kalinowski, K. and Kaula, R. Zesz. Nnuk. Polirwh. S/a.sk.. Cb-rr., 1995, 225, I I l-l 19. (In Polish) An increasing amount of aeration atr in the flotation widened the spectrum of floatability of the particle feed.
97101620 Enhanced coal cleaning
column
flotation
performance
for fine
Honaker, R. Q. and Mohanty. M. K. Miner. Eng., lYY6, 9, (9), 931-945. Previous experimental studies show that the froth flotation process is efficient in recovering heavy middling particles, which negatively affects the recovery-grade curve achieved for fine coal recovery. Experimental and theoretical results indicate that the recovery of middling particles can he reduced from 25’% to 10% using flotation columns in a multi-stage cleaning approach. thereby improving the overall separation performance. To evaluate the use of multi-stage cleaning, a continuous column model has been developed which incorporates selective and non-selective froth dropback, and feed component flotation kinetics. For kinetic rate limiting conditions, separation performance was found to substantially improve with the use of multi-stage cleaning, which agrees with the experimental findings. Economic justification of the use of multi-stage column treatment must he based on enhancements in product grade and/or mass yield.
97101621 E.s.r. studies of five coals before and after reaction with spin traps (microwave-driven) Monsef-Mirzai, P. and McWhinnie, W. R. I;lre/. 1996. 75. (14). 1676IhXO. The paper reports microwave-driven reactions of the spin trap phenyl-N-rbutylnitrone with five coals of different rank. Comparison is made hetween the e.s.r. data for the raw coals and the spin-trap-treated materials. It is concluded that the major effect of the spin trap is to alter relaxation time. A new microwave method of char generation is introduced, e.s.r. data for the new chars are also presented and the reactions of the coals with diiodine are re-examined. Results are compared with those of other recent investigations of diiodine ‘complexes’. The increase in spin density observed may result from a favourahle change in relaxatmn time. as a result ot intercalation of the halogen for one suite ot radicals. rendering them detectable in the e.s.r. experiment. The materials were also examined using X-ray photoelectron spectroscopy (XPS). and it is suggested that the common assumption that diiodine is present as 1: molecules in these coals may need revision.
Fuel and Energy Abstracts
May 1997
137
97101606
Capacity
of high-pressure
grinding
rolls
Austin. L. G. er al. Trrrjrv. Sec. Mitl., Metall., Eqdor.. 1995, (Puh. 1996). 29X. hS-73iSection 3 Tests were carried out on six US coals and a crystallized quartz in an instrumented laboratory high-pressure grinding rolls machine equipped with IOO-mm-diameter rolls. As expected, the specific capacity decreased with increased grinding pressure for each material tested. There were significant differences among the six coals in the critical angle of nip, the effective feed porosity and the variation of strain at the gap relative to the grinding pressure. Although a precise correlation was not ohtained. the overall effect of these factors was that, at a given grinding pressure, the specific capactty increased as the Hardgrove grindability index of the coal increased.
97101609
Classifier
mills for coal grinding
and drying
Galk. J. and Peukrrt. W. Pro<. A?lnrr. Il~r. Pirtshurgh Coal Cortf., 1995, 12, 567-512. A special air classtfier mill for coal grinding is presented in this report. Air classifier mills use the two fundamental process steps grinding and classifying in one machine. In this report an air classifier mill, come typical process data as particle \ize distrihutions, possible throughput and an industrial application are shown.
97/01610 cleaning
Coal agloflotation: of town gas soils
a remediation
technique
for
Joshi. M. M. and Let. S. J. Hnzarl/. M~rrcr., 1906, 49. (2-3), 155-163. The present study investigates the use of a hydrophobic coal surface for the adsorption and removal of oily/tarry contaminants such as PAHs from town gas soils. The agloflotation process uses a coal-soil-water mixture to achieve simultaneous removal of mineral matter from coal. The coheneficiation achieves YOr/, and higher decontamination for soil and 40% and higher ash removal from coal.
Coal hydrogenation 97101611 catalyst (MOOS-Ni0/A1203) ‘waste’
catalysis
using
industrial
Wang, R. et al. Fuel. 1996, 75, (14). 1671-1675. A commercial MoQ?-NiO/A1207 (Akzo 153) catalyst used in a coal-liquid upgrading process for 400 h. to promote low-severity coal hydrogenation was investigated. Such a reaction system is considered to he economical. A tubing homh microreactor (25 cm” capacity) was used for dissolution reactions of a low-rank British bituminous coal in an industrial recycle solvent under various conditions. Results show that this catalyst ‘waste’ exerts considerable influence on the coal hydrogenation reactions compared with a fresh sulfided catalyst of the same type. This research has also improved understanding of the catalysed coal hydrogenation mechanisms and identified a potentially beneficial method of disposal of industrial catalyst wastes.
97101612 tion
Composition
and method
for inhibiting
coal oxida-
Roe. D. C. Can. Pat. Appl. CA 2,165,494 (Cl. CO9K3100). 21 Jul 1996. US Appl. 376.317. 20 Jan 1995; 20 pp. The paper describes composition and a method for inhibiting coal oxidation. Coal oxidation is inhibited by applying an aqueous solution of cationic polymer. e.g. adipic acid-diethylenetriamine-epichlorohydrin copolymer or aminomethylated polyacrylamide, to coal surfaces which are exposed to air. The compositions are preferably applied to coal as foams.
97101613 Demineralization of a bituminous flotation before obtaining activated carbons
coal
by froth
Rivera-Utrilla, J. et ul. Carbon, 1996, 34, (7), 917-921. Demineralization of a Spanish bituminous coal by froth flotation was carried out. The effect of the particle size, solution pH, and the presence of electrolytes on the process yield was investigated. Three activated carbon samples were obtained by steam activation of the floated coal. These activated carbons were texturally characterized using of N?, CO: and benzene adsorption. The results obtained with these three adsorptives are very similar, which indicates that the microporosity of the activated carbon samples is accesaihle to the molecules of the above compounds.
97101614 classifier.
The
design
of a three-product
mechanical
spiral
Korsak, L. L. and Tokareva. I. S. Koks Khim. 1995, (h), 29-31. (In Russian) The performance is studied of three-product mechanical spiral classifier with vortex generator and conical packings that create a centrifugal pulp stream at the lower section of a bath. The spiral classifier can he used for the concentration of coal slurries before feeding to the jigging machine.
Determination of the real lower limit 97101615 particles separation in the Reichert spiral separator
of
coal
Sweierkot-Kopala, et ul. Zesz. Nauk. P&tech. S/ask., Gorrl., .1995, 22.5. 263-283. (In Polish) A study on the determination of the lower limit of coal particle size in the Reichert spiral separator of the LD 4 type. Experiments were carried out with the coal particle size of 0.3-0.0, 0.5-0.0, and 1.0-0.0 mm. The feed was prepared in two versions: (I) simplified: and (2) using the whole fraction. It
Solid fuels (preparation)
was found that the lower limit of particles to he separated was 0.04.5 mm. if the particle size of the charge was < 1 mm. This result is hetter than that specified by the manufacturer (i.e. 0.075 mm).
97101616 pressure
Devolatilization
of
large
coal
particles
at high
Eatough, C. N. and Smoot, L. D. F‘uel, 1996, 75. (13). IhOl-1605. Experiments were carried out to measure the devolatilization times of large (0.1 and 0.2 g) Utah high-volatile bituminous B (hvBh) and North Dakota lignite coal particles in the 15-30 s range in air at IO1 and 507 kPa and air temperature 9tlO and 1200 K in a convective flow reactor. Visual observations indicated infrequent heterogeneous ignition of the lignite prior to devolatilization and occasional explosion of hituminous coal particles during devolatilization. Devolatilization times were correlated with temperature, pressure and particle.
97101617 DRIFT spectroscopic characterization ples modified by chemical treatments
of coal sam-
Nosyrev, I. E. ef ul. Fuel. 1996, 75. ( 13). 1549-l 5Sh. Diffusion reflectance IR spectroscopy was employed to characterize the modifications afforded hy several chemical treatments to the main functional groups of a hituminous coal. The starting materials were the polyanions and potassium coal adducts obtained from the parent coal. treated with potassium according to the Sternherg and Lazarov reactions. The results show the differences in the reactive sites involved in theqe reactions and those in the hehaviour of these sites during protonation or alkylation. Taking into account the semiquantttative result\ of the IR analysis, the participation of several active sites in the total hydrogen transfer was estimated. indicating the role of quinonic. aromatic and alkyl groups.
97101616 Effect of molecular weight of polyethylene frothers on their performance in low rank coal flotation
glycol
Saleh, A. M. and Iskra, J. Fizyhochun. Prohl. M/neralrrrgii. 1996, 30. 33-40. A study was conducted to explore the effect ot the molecular weight of polyethylene glycol frothers on flotation of low-rank coal. Four frothers of molecular weights of 400. 600. 1000, and 1500 were tested (e.g. PG 400. PG 600, PG 1000, and PG 1500. respectively). Polyethylene glycol of molecular weight 1000 gave the worst results. The best performance (i.e. high flotation recovery, rate, and selectivity) was observed for PG 600, whereas PG 400 performed worse than PG 600 and hetter than PG 1000 and PG 1500. The better performance of PG 600 was attrihuted to its greater surface activity.
97101619 floatability
Effect of the intensity of aeration air on distribution in batch coal flotation experiments
the
Kalinowski, K. and Kaula, R. Zesz. Nnuk. Polirwh. S/a.sk.. Cb-rr., 1995, 225, I I l-l 19. (In Polish) An increasing amount of aeration atr in the flotation widened the spectrum of floatability of the particle feed.
97101620 Enhanced coal cleaning
column
flotation
performance
for fine
Honaker, R. Q. and Mohanty. M. K. Miner. Eng., lYY6, 9, (9), 931-945. Previous experimental studies show that the froth flotation process is efficient in recovering heavy middling particles, which negatively affects the recovery-grade curve achieved for fine coal recovery. Experimental and theoretical results indicate that the recovery of middling particles can he reduced from 25’% to 10% using flotation columns in a multi-stage cleaning approach. thereby improving the overall separation performance. To evaluate the use of multi-stage cleaning, a continuous column model has been developed which incorporates selective and non-selective froth dropback, and feed component flotation kinetics. For kinetic rate limiting conditions, separation performance was found to substantially improve with the use of multi-stage cleaning, which agrees with the experimental findings. Economic justification of the use of multi-stage column treatment must he based on enhancements in product grade and/or mass yield.
97101621 E.s.r. studies of five coals before and after reaction with spin traps (microwave-driven) Monsef-Mirzai, P. and McWhinnie, W. R. I;lre/. 1996. 75. (14). 1676IhXO. The paper reports microwave-driven reactions of the spin trap phenyl-N-rbutylnitrone with five coals of different rank. Comparison is made hetween the e.s.r. data for the raw coals and the spin-trap-treated materials. It is concluded that the major effect of the spin trap is to alter relaxation time. A new microwave method of char generation is introduced, e.s.r. data for the new chars are also presented and the reactions of the coals with diiodine are re-examined. Results are compared with those of other recent investigations of diiodine ‘complexes’. The increase in spin density observed may result from a favourahle change in relaxatmn time. as a result ot intercalation of the halogen for one suite ot radicals. rendering them detectable in the e.s.r. experiment. The materials were also examined using X-ray photoelectron spectroscopy (XPS). and it is suggested that the common assumption that diiodine is present as 1: molecules in these coals may need revision.
Fuel and Energy Abstracts
May 1997
137