01 Solid fuels (preparation)

96104669 Improved approaches for dewaterlng of fine coal 96104670 Oxidative pretreatments for the enhanced removal Yang! J. et al., Proc. Process. Hydrophobic Miner. Fine Coal, UBC- of organic sulfur from coal M&r11 Bi-Annu. Int. Symp. Fundam. Minera. Process, Canadian Inst. of Palmer, S. R. et al., Coal&i. Technol., 1995, 24, (2), 1713-1716. Mining, Metallurgy & Petroleum, 1995, 503-511. The paper compares the removal of organic sulphur from coal by air oxida- The removal of moisture from ultrafine clean coal (minus 100 mesh) to tion with base and MeOH compared with oxidation with more expensive below 20% levels is difficult using conventional dewatering equipment. oxidizing agents. Inexpensive oxidants appeared to be just as good as, if The paper describes a couple of dewatering approaches which are effective not superior to expensive oxidizing agents for the oxidative pretreatment in providing filter cakes containing less than 20% moisture. step in desulphurization.

96104670 improved efficiency of coal cleaning using a flota- tion-regrindlng~flotation process Polat. H. and Chander. S. Proc. Process. Hvdroohobic Miner. Fine Coal, UBC:McGill Bi-Annul Int. Symp. Fundam.. M&era. Process, Canadian Inst. of Mining, Metallurgy & Petroleum, 1995, 179-189. Several approaches have been suggested in the past lo improve the flota- tion cleaning of coal at fine sizes. In this investigation, different circuit configurations are compared to show that the choice of the most effective approach is a function of coal sype. Some coals could be further cleaned by recleaning the froth products. For such coals, column flotation is likely to be very beneficial. For other coals, regrinding the coarse coal flotation product prior lo flotation improved the grade. This approach gave better performance compared to fine

+ rinding the feed, followed by its flotation.

Presents the results of four dlf erent coal samples.

96104671 The influence of mineral matter on the separation of amorphous marine kerogens using density gradient centrifugation Hartners. W. A. Ora. Geochem., 1995. 23, (81. 777-784. The :ap& describes cow D-gradient cer&ifugahon (DGC) was applied to three amorphous marine kerogens. SEM-energy dispersive spectroscopic analysis revealed petrographic distinct macerals between fractions of low and high density. However, these microscopic observations were not accompanied by chemical differences, as revealed by Curie-point pyrolysis.

96104672 Kinetics of heat treatment of Kansk-Achinsk Basin brown coals Boiko, E. A. Khim. Tverd. Topl. (Moscow), 1995, (5), 31-37. (In Russian) Describes a method of complex thermal analysis of coal. Processes of moisture evaporation, devolatilization with separate analyses of tar and gas evolution. and reaction of solid residue with 0 of air were studied.

96104673 Method for dewatering coal tailings using DADMAC/vinyl trialkoxysilane copolymers as a coagulant Kerr, E. M. and Ramesh, M. (Assigned to) Nalco Chemxal Co., US Pal. L&.5,476,522, Dec. 1995. Describes a method where coal tailines are concentrated and coal oroducts dewatered using a copolymer of dia~lyldimethylammonium halide and a vinyl alkoxysilane, preferably a copolymer of diallyldime~hylammonium chloride and vinlytrimethoxysilane as a coagulant.

96104674 Mlcroblologlcal desulfurization of coal Twardowska, I. Przegl. Gorn., 1995, 51, (lo), 29-33. (In Polish) Presents the current state of research and development of desulphurization of raw coal (fines), a subject of vital importance for environmental protec- tion. Particular advantages of the biological method for coal desulphuriza- tion are indicated, such as low energy consumption for the biochemical reactions and for the chemical reagents, which are in addition cheap and easily available. Among the principal advantages is the zero coal loss and absence of waste with moreover high efficiency of pyrite sulphur removal.

96104676 NO, reduction by coal brlquets Garcia-Garcia, A. el al., Coal Sci. Technol., 1995, 24, (2), 1787-1790. Describes how fuel briquets were prepared using humic acids as a binding agent which also functioned as a carbon-based reducing agent lo reduce NO, emissions upon combustion.

96104676 Operation of coal pulverizing system with ball drum mills In crushing of low-grade anthracite Kucherenko, P. P. Energ. Elektrif: (Kiev), 1995, (3), 10-12. (In Russian) Describes a coal pulverization system with fuel oil furnace-dryer, coal pulverization system with a boiler and gas heater, and closed loop coal pulverization system with a boiler.

96104677 Organic sulfur removal from coal by rapid pyroly- 81s with alkali leaching and denslty separation Sugawara, K. er a/., Coal Sci. Technol., 1995, 24, (2). 1709-1712. High-temperature alkali treatment with KOH was combined with rapid pyrolysis in a free-fall reactor to successfully reduce the organic sulphur content in coal fractions separated by density differences by float-sink processes.

96104679 The P

ath of sulfur during the blo-oxidation of pyrite by Thlobaclllus errooxidans Rojas-Chapana, J. A. et al., Fuel, Jun. 1996, 75, (8), 923-930. The detection of colloidal sulphur with dimensions of 20 (sometimes up to 70) to 4 nm as intermediates of sulphide bio-oxidation by Thiobacillus ferrooxidans presents new possibiliries for the exploration of the leaching mechanism of inoreanic sulohides and for the use of sulohur in bacterial metabolism. The liberation of sulphide-S from a crystallized compound in an interfacial reaction, the formation and stabilization of colloids (by bio- logical macromolecules) in an organic capsule around the bacterial cell and the life cycle of colloids during the leaching, including their final con- sumption, are discussed. An illustration is provided explaining the genera- tion, stability and metabolism of sulphur from pyrite.

96104600 Possibilities of raising the rate of fine coal flotation Rubinstein, J. B. er al., Proc. Process. Hydrophobic Miner. Fine Coal, UBC-McGill Bi-Annu. Int. Symp. Fundam. Minera. Process, Canadian Inst. of Mining. Metallurgy & Petroleum, 1995, 165-178. Following fine grinding, the physical and physico-chemical properties of coal oartlcles chance: free macroradicals are formed. the average size of carbdn lavers decreases. the orocess of structure amorbhization &initiated. the aromitic constituenis are&transformed, and the probortion of disordered carbon in the side chains increases. As a result the adsorption ability of the coal particles increases. A series of tests conducted with narrow s&e frac- tions revealed their floatabilitv and the effect of fines content on the flota- tion response. The flotability distribution function was obtained using different reagents. The results demonstrated a high efficiency of the modi- fied methods which include selective coagulation, selective flocculation and oil agglomeration.

96/04661 Prevention of coal selfignition by lowering its initial temperature Portola, V. A. Bezop. Tr. Prom-k., 1995, (6), 29-30. (In Russian) Discusses how the endogenic fires due 10 selfignition of coals can be prevented by lowering the oxygen concentration in the air and oxidation rate constant. The energy of interacting components must be reduced to decrease the amount of reacting oarticles and enerev release. The enerev of interactin p components can be-r‘cduced by prelimyiary cooling of the-ioal pile and dtermg air by using low-temperature heat-transfer agents. Dis- cusses the dependence of the heat released from the coal during initial and low temperafures on the temperature drop during cooling. _

96104682 Recent advances In separatlng and characterlzlng single coal macerals Crelling, J. C. and Bensley, D. F. Coal Sci. Technol., 1995, 1, 235-238. Discusses the methods for separation and characterization of individual coal macerals. Also discusses the cut point determination, acid demineral- ization, cryogenic treatment, semicontinuous centrifugation, rotational polarization reflectance, and fluorescence spectral characterization.

96104683 Research on the thermal strength of dyad gas oven brlquet Xu, D. el al., Huanjing Huaxue, 1996, 15, (2), 151-154. (In Chinese) Describes a study of the thermal strength of briquettes during coking.

96104684 dewaterlng

Role of lnterfaclal phenomena In flne coal

Xu. 2. el al.. Proc. Process. Hvdroohobic Miner. Fine Coal, UBC-McGill Bi-Annu. Int; Symp. Fundam. kinera. Process, Canadian Inst. of Mining, Metallurgy & Petroleum, 1995, 513-525. Control of interfacial phenomena for improved fine coal filtration rate and dewatering efficiency is an attractive approach due to its great flexibility. However, the complex nature of interfacial phenomena in fine coal dewatering makes it a challenge to derive practical applications. In this namer. the filtration oerformance of fine coal slurrv was analvzed bv con- sidering the filtration as a process of fluid flowing through capillary chan- nels formed from the packing of fine coal particles. The performance of filtration was evaluated by the filtration rate and the moisture content of filter cake attainable. The.former determines the throughput and the latter determines the quality of final product of dewatering.

96104685 Roll-press brlquetting Komarek, R. Mining Mug., Jun. 1996, 174, (6), 356, 358, 360. Discusses the compacting of mineral products into briquettes which is worrh considering for a number of reasons. Briquetting increases bulk den- sity for easier handling, shipping or disposal; prevents caking or bridging insilos, hoppers and metering equipment; reduces dusting and segregation of fines in handling; improves remelt yields: and, in the case of fuels, improves burning characieristics. .

334 Fuel and Energy Abstracts September 1996