0 7 Solid fuels (preparationj

97102566 Coking mechanism of zeolite for supercritical fluid alkylation of benzene Gao. Y. CI ill. P~~cerv Tcchr~ol. Proc.. 1096. 17. (Hieh Pressure Chemical Engineering). ISI-156.

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The paper descrihea the alkylation of benzene with ethylene over Y-type reoliie and under supercritical conditions in benzene solvent. Supercritical conditions result in a decrease in the catalyst deactivation rate and decreases the selectivity to by-products. The existence of some coke precursors that are partially removed from the catalyst surface has heen shown through experiments. Formation of by-product xylenes were decreased, which was attributed to a high diffusivity in the supercritical fluid.

97102567 Concentration of coal fines by flotation Malysa. E. and Sanak-Rydlevskan. S. Olqnshch. Rud. 1996, (4). 24-26. (In Russian) Gas coal flotation was studied at three coal mines in Poland. Coal fines were observed to float well and their commercial concentration permits the production of high-grade concentrates. The reagents used in the process include gas oil (collector) and various frothers, e.g. pine oil, heavy alcohols, flotanol and octanol.

97102568 The design of the Landau coal processing plant, South Africa Boyd. 1. W. and England, T. Recent Adv. Coul Proce.m., 1996, I, (New Trends in Coal Preparation Technologies and Equipment), 835-841, 861. Two identical modules for treating coal in the size range 0.5 x 75 mm and a combined fine coal spiral plant to treat the 0.15 x 0.5 mm material comprise the processing plant.

97102569 Desulfurization of coal using methanol Guanghui, W. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13. (2), 916-921. An investigation into sulfur removal from coal by methanol in a 300 ml batch reactor. The Illinois IBC-108 coal used is highly beneficiated and contains mainly organic sulfur. This means the results are also applicable to organic sulfur removal. Sulfur removal increased with increases in temperature, reaction time and the methanol used, while it decreased with the amount of coal used. Coal pyrolysis was also explored. The best results were obtained at 5OO’C, 60-90 min reaction time and very small amounts of coal, achieving a total sulfur removal of 86%.

97102570 Desulfurization of Turkish lignites by NAOH leaching Renda, D. Changing Scopes Miner. Process., Proc. Int. Miner. Process. Symp., 6th, 1996, 489-491. Edited by Kemal, M. B., Rotterdam, The Netherlands. The paper studies sulfur removal by NAOH leaching from Tuncbilek Omerler lignite. containing 4.41% total sulfur on dry basis, was studied.

97102571 Electrostatic apparatus with annular electrodes for separation of powdered coal from pyrite and ash minerals Brown, D.K PCT Int. Appl. WO 97 09,398 (Cl. CIOL), 13 Mar 1997, US Appl. 519,924. 28 Aug 199.5, 13 pp. The title apparatus is presented. Powdered coal feed is passed through a rotating-ring system with annular electrodes for a positive charge on the coal, and negative charge on the pyrite, ash-producing compounds, and any toxic minerals. The apparatus chamber is maintained at a decreased pressure, and the electrostatically charged feed is passed for the mechanical separation of coal having increased purity from the mineral fraction. The electrostatic charge an coal powder is typically applied by a rubbing contact an Cu-alloy charging rings in the apparatus. and the electrical charge stahility is increased by removal of coal moisture using vacuum exhaust.

97102572 An empirical description for the classification in an inclined counter-flow settler Thompson, P. D. and Galvin, K. P. M&r. Ens., 1997, 10, (l), 97-109. Significant cut-point control in size classification was found in an inclined counter-flow settler. The inclined counter-flow settler is therefore a possible alternative to using hydro-cyclones. Tests were conducted by using eight different feed pulp densities, ranging 2.4-21.7x solids. The classification or partitioning of the particles between the underflow (coarse) and overflow (fine) streams was determined for each of the feed pulp densities at six different flow rates. Excellent agreement was found between the reduced partition curves from 38 of the 48 tests, but poor agreement for experiments conducted at the lowest flow rate and or feed pulp densities.

97102573 Energy conservation and intensification of peat processing Bogatov, B. A. Izv. Vyssh. Uchebn. Zuved. Energ. Ob’edin. SNG, Energ., 1995, (S-6), 91-95. (In Russian)

97102574 Factors influencing the moisture content of coarse coal after centrifugation Firth, B. A. Coal Prep. (Gordon & Brertch), 1996, 17, (l-2), 117-136. The moisture content of coal from a single centrifuge was measured with an online moisture monitor. This was installed on the product belt immediately after a first coarse coal centrifuge at two coal preparation plants. After

characterization of the coal samples, properties corrrlating with moisture content variations were identified. In addition, basic studies were conducted with a laboratory centrifuge specifically designed to characterize various coarse coal samples in terms of their water retention capacity. The results showed the moisture of the coarse coal can vary hy at least one percent at a particular plant, and a number of percentage points between plants. An empirical model has heen developed which can explain ahout 80% of the variation of the moisture content of the 25 coarse coal samples. Four principle controlling factors were discovered: (I) the amount ot moisture held internally within the coal, (2) the specific surface area of the coal, (3) the rank of the coal, and (4) the amount of ultra-fine material aahociated with the coarse coal, which can affect the drainage of water from the coal particle surface. This model provides an estimate of the moisture level which can he achieved hy centrifugation of coarse coal.

97102575 Fine coal washability-liberation analysis by cone- beam X-ray microtomography Miller, .I. D. and Lin. C. L. Proc. Arrnu. Irlt. Pitrsbwgh Cord Cotr/‘., 1996. 13, (2). 852-859. Cone-beam x-ray microtomogography provides the basis of a new method for direct determination of the three-dimensional liberation spectrum of multiphase particles 100 in size or less. More detailed and accurate washability analysis in fine coal characterization may arise from such a technique. Previous research has demonstrated the ahility to USC traditional medical X-ray CT scanners to determine the liberation spectrum of coarse coal particles of I cm in size (washahility analysis). Now it i< possible to determine fine coal (- 100 mesh) washability by, cone-heam microtomo- graphy. This new microtomography technique gives a three-dimensional reconstruction image array prepared directly from the two-dimensional projections for cone beam geometry. This technique offers the potential to overcome many of the limitations of current techniques being used for fine coal washability analysis.

97102576 Flocculation of fine coal using synthetic and biologically derived flocculants Raichur, A.M. et al. Miner. Metall. Process. 1997. 14, (I), 22-26. Coal can be flocculated using biopolymers derived from Mycobucterium phlei. They prove more effective than synthetic polymer flocculants. Higher flocculation efficiencies were achieved in shorter times and at lower concentrations with hiopolymers. In addition, the coal flocculants formed using hiopolymers were more compact and settled at a much higher rate. Adsorption of the hiopolymers resulted in a more hydrophobic coal surface. For both coals, the rate constants and the hydrophobic mass tranater coefficients were the largest when hiopolymer was used as the flocculating agent.

97102577 High frequency stimulated coal upgrading Nazimov, S. A. and Korohetskii, I. A. Proc. Annrc. htt. Pittsburgh Coul Conf:, 1996, 13, (2), 891-896. A siudy was carried out to examine the conversion of coal by low power microwave radiation for use as a preliminary step of coal upgrading. Changes in characteristics of Kararakanskii coal in microwave field were investigated. The raw coal and coal-water mixture were treated and an increase in the carbon content in treated samples was observed with a decrease in the oxygen content in the coal treated in the presence of water. The alteration of the DTG curve patterns was shown for rhe pre-treated samples.

97102578 Improved dewatering of coal by steam pressure filtration Geri, S. and Stahl. W. Coal Prep. (Gorffon & Bretrch), 1906. 17. (I-Z), l37- 146. Combined mechanical and thermal dewatering make the use of steam as pressurizing gas phase advantageous. In contrast to conventional solid- liquid separation processes, steam pressure filtration can provide an economical and effective technique. The procedure is detailed and evaluated.

97102579 Location of the hydrocarbon potential during coal pyrolysis: implications on the chemical modelling Langlois, E. et al. Prep. Pap. Am. Chem. Sot., Dig,. Fuel Chem.. 1997, 42. (I). 112-115. Subjecting an immature coal to artificial maturation allows to compare the the yields and composition of free hydrocarbons, asphaltenea, resins, and residual kerogen. It was shown that a large part of the hydrocarbon potential initially present in the kerogen is progressively transfered into polar components.

97lO2560 Methods for preparing and monitoring of heavy media in coal beneficiation Anuprienko, T. A. and Nikitin, I. N. Obogashclr. Rud, 1996. (4), I I-12. (In Russian) The authors describe procedures for technological monitoring of magnetic fluid preparation based on synthetic magnetite. These permit monitoring of the concentration of Fe’+ and Fe’+ as well as oleate ions used as suspension stabilizers.

214 Fuel and Energy Abstracts July 1997