01 Solid fuels (preparation)

95/02311 Effect of llaht heat treatment on pyrolysis reactivity of brown coal

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Havashi. J. I. er al.. Enerav & Fuels, Mar.-Apr. 199.5, 9, (2), 284-289. A brown coal (Yalioum) was heat-treated in a nitrogen atnidsphere, and the original and heat-treated coals were subjected to flash pyrolysis by using Curie-point and entrained-flow pyrolyzers. The yield of CO,, the most abundant product in the heat treatment stages, was varied by the heat treatment temperature in the range of 0.4-11 wt% and was employed as a measure for heat treatment severity. The heat treatment gave both positive and negative effects on the pyrolysis reactivity of coal. In the low-severity heat treatment regime where the CO, yield was less than 5 wt%, the tar yield increased and the char yield decreased with increasing severity.

95102312 Effect of the extraction on the quantltatlve content of trlterpenolds In peat extracts Lishtvan, I. I. et al., Khim. Tverd Topl. (Moscow), 1994, (4), 5-8. (In Russian)

95102313 Effect of the ropertles of coal surface and floccu- lant type on the flocculat on of fine coal P Palmes, J. R. and Laskowski, J. S. Trans. Sot. Min. MetalL Explor., 1994, 294, 218-222. Discusses a study of the flocculation of coal fines of different wettability. The effects of coal oxidation, hydrophobicity, and wettability are also discussed.

95102314 Flotatlon characterlstlcs of oxldlzed coal Sarikaya, M. and Ozbayoglu, G. Fuel, Feb. 1995, 74, (2), 291-294. The floatability of oxidized coal was investigated by means of electroki- netic studies, contact angle measurements and flotation tests. Electrokinetic measurements showed that the zeta potential of unoxidized and oxidized coal samples depends on pH. Hydroxonium and hydroxyl ions are poten- tially significant ions, both for oxidized and unoxidized coal. Increasing oxidation times decreased the measured iso-electric points and increased :he negative zeta potential. In the presence of cationic collectors the nega- tive value of the zeta potential for oxidized coal was changed to a positive value below pH 9.3-10.9 depending on the type and concentration of col- lector used. Contact angle measurements indicated that the natural floatability and unoxidized coal was found to deteriorate on oxidation. Addition of cationic collectors increased the value of the contact angle of oxidized coal.

95/02315 Fluldlzed oxydesulfurlzatlon of coal Diver, J. R. PCT Int. WO.94,22,989, Oct. 1994. A method and apparatus for removing sulphur in coal prior to combustion.

95102316 Formation of free radicals durlng drying and oxlda- tlon of a llgnlte and a bltumlnous coal Can, R. M. et al., Fuel, Mar. 1995, 74, (3), 389-394. The changes in radical concentrations and species brought about by vac- uum and

f as flow drying of New Vale lignite and Stockton bituminous

coal samp es were studied. Vacuum drying produces a sudden increase in concentration, flow drying a more gradual but ultimately greater one. For both coals the changes depend on a balance between decarboxylation, which produces new radical sites, and removal of moisture from heter- oatomic sites within the coal macrostructure. This balance is influenced by the drying method used. Exposure of dried samples to dry air produces changes in radical concentration consistent with the findings of previous oxidation studies of these coals.

95102317 Grlndlng behavlor of coal blends In a standard ball- and-race mill Cho, H. and Luckie, P. T. Energy & Fuels, Jan.-Feb. 1995, 9, (l), 59-66. An investigation was carried out to predict the size-composition make-up of the product of a coal blend ground in a ball-and-race mill using the breakage characteristics of the individual components determined by sepa- rate grinding. Sometimes a pseudolinearity can be observed when the changes in the grinding rate for the components in the mixture occur in a compensated manner. In this case, the HGI of the blend appears to be additive. However, the composition of the product size intervals is differ- ent from the weighted sum of the two products from separate grinding. An empirical equation was used to predict the change in the breakage parame- ters as a function of the blending ratio and the difference between the relative strength of the two materials. The grinding of the individual coals in the Hardgrove Mill exhibited non-first-order grinding kinetics.

95102316 Image analysis characterlzatlon of pyrlte In fine coal flotatlon Wang, D. et al., Trans. Sot. Min. Metall. Explor., 1994, 294, 154-159. The flotation behaviour of a -28 mesh Pittsburgh No. 8 coal sample is investigated through the use of SEM in conjunction with image analysis. Release. analysis is used to generate the flotation products, which are then characterized to provide the particulate composition in terms of pyrite, mineral matter and carbonaceous material. The results indicated that the material recovered in the first stage of release analysis tends to be well- liberated carbonaceous material.

95lO2319 slurries

lndustrlal tests of reagents for flotatlon of coal

Egorov, V. N. er al., Koks Khim., 1994, (8), 8-9. (In Russian)

95102320 An Integrated heavy medla cyclone-flotatlon sys- tem for coal cleaning Polat, M. et al., Trans. Sot. Min. Metall. Explor., 1994, 294, 206-212. Describes how flotation was used to achieve improved separation of mag- netite from the float and sink products obtained from heavy medium sepa- ration and to reduce. the load of the medium cleaning circuit. The study was carried out in two successive phases.

95102321 lnvestlgatlon of the breaka B

e propertles of compo- nents In mixtures ground In a batch ba l-and-race mill Cho, H. and Luckie, P. T. Energy & Fuels, Jan.-Feb. 1995, 9, (l), 53-58. The breaka

% e characteristics of mixtures of materials were investigated in a

laboratory all-race mill. A study of the grinding kinetics of the compo- nents in a binary mixture showed that the breakage rate of one material was affected by the presence of the other material. The breakage rate of the relatively weaker material increased and, conversely, the breakage rate of the stronger material decreased. The degree of the change in the breakage rate was dependent on the blending ratio and the relative difference in the ‘strength’ of the component. Because there was a consistent pattern, an empirIca relationship for this variation was developed.

95102322 Mechanochemlcal transformatlon of coal asphaltenea Proidakov, A. G. et al., Khim. Tverd. Topl. (Moscow), 1994, (4), 40-44. (In Russian) The paper describes how asphaltenes are isolated from a brown coal extract and treated in a planetary grinder for 15 minutes. During grinding, the asphaltenes undergo mechanical disintegration with subsequent stabiliza- tion of the active fragments thus formed into oils and preasphaltenes.

95102323 dian coals

Mercury poroslmetry of upgraded western Cana-

Friesen, W. I. and Ogunsola, 0. I. Fuel, Apr. 1995, 74, (4), 604-609. Mercury porosimetry was used to study changes in the pore structure of three western Canadian low-rank coals treated in three different atmo- spheres (nitrogen, steam and combustion products) at temperatures up to SOO”C. The intrusion curves are well described by two diffeent power laws in the pressure range 0.1-200 MPa. Principal-component analysis was per- formed to determine relations among the power-law exponents, equilib- rium moisture and volatile matter.

95102324 Mlcroblal desulfurlzatlon mechanisms Olson, E. S. et al., Prepr. Pap.-Am. Chem Sot., Div. Fuel Chem., 1994, 39, (3), 738-740. Sulfur-specific desulphurization with Rhodococcus rhodochrous IGTSB and related microorganisms may be a useful technology for upgrading high-sulphur carbonaceous materials to more environmentally acceptable fuels. A study of the model compound with the organism showed that dibenzothiophene was converted to a 2-hydroxybiphenyl or 2,2’-dihydrox- ybiphenyl, depending on whether growth or non-growth conditions were used in the desulphurization experiments.

95102325 NO reduction by activated carbons. 2. Catalytic effect of potasslum Illan-Gomez, M. et al., Energy & Fuels, Jan.-Feb. 1995, 9, (l), 97-103. The results of an investigation are reported concerning the NO reduction activity of different carbons loaded by ion exchange with varying amounts of a potassium catalyst. The samples were characterized by physical adsorption of CO, (at O’C) and N, (at -196’C) and by chemisorption of CO, at 25O’C. The reactivity of the pure carbons was determined in both NO and CO,. The catalytic effect of potassium in NO reduction was evalu- ated in a fixed-bed flow reactor at atmospheric pressure using two types of experiments: (i) temperature-programmed reaction in a NO/He mixture; and (ii) isothermal reaction at 300-6OO’C. The reaction products were monitored in both cases, thus allowing detailed oxygen and nitrogen bal- ances to be determined.

95102326 NO reduction b r

activated carbons. 3. Influence of catalyst loadlng on the cata ytlc effect of potassium Illan-Gomez, M. J. et al., Energy & Fuels, Jan.-Feb. 1995, 9, (l), 104-111. The results of an investigation are reported concerning the NO reduction activity of a carbon loaded by impregnation from solution with varying amounts of a potassium catalyst. The samples were characterized by CO, chemisorption at 250°C and NO chemisorption at 6O’C. The catalytic effect of potassium in NO reduction was evaluated at atmospheric pressure in a fixed-bed flow reactor.

174 Fuel and Energy Abstracts May 1995