The pyrolysis of a suite of brown coal samples and bituminous coal maceral concentrates is investigated by non-isothermal thermogravimetry. The TG data for these coals reveal a two.stage pyrolysis process. The activation energy for the primary pyrolysis stage is considerably higher than that for the secondary pyrolysis stage. It is evident that a particular coal may be characterised by the weighted mean apparent pyrolysis activation energy which correlates with the corresponding specific energy of the coal.

Cross polarization carbon-1 3 nuclear magnetic resonance spectroscopy with magic angle spinning (CP-MASS) was used to analyse for various forms of carbon in soils, a moss peat, hydrochloric acid insoluble residues from soils and peat, and litter from beech and pine trees. The chemical composition of the litters was also investigated by conventional techniques.The results show that hydrolysis with hydrochloric acid extraction removes nearly all oxygenated alkyl carbon from the soils used. It is shown that humification pathways in which carbohydrates are incorporated into humic substances via nonhydrolysable linkages are not important for the soils investigated in this work.CP-MASS data suggest that the percentage of aromatic carbon in pine leaves increases with increase in ageing time. The results for the beech leaves are not sharply defined.

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In a comparative study, the quantity of accumulated organic matter in, and the nutrient composition of the forest floor and topsoil (0-20 cm) of indigenous (beech or podocarp) forests and nearby Pinus radiata plantations in five widely separated forest sites in the South Island of New Zealand were measured. Total mass of forest floors in native and radiata plantation stands ranged from 25 to 464 and 9 to 79 t/ha, respectively. Native forest stands apparently accumulated larger amounts than nearby radiata pine stands, especially in the West Coast forests. In exotic plantations, the nett accumulation was modified by management practices such as burning, during the process of converting native forests to pine plantations, and stand thinning.Except in Nelson forests, forest floors in native stands had larger contents of carbon and nutrients than those of nearby radiata pine sites. No consistent differences were found in carbon and nutrient concentrations in topsoils of native and exotic forests except in the 9-year-old radiata pine stand in the Hochstetter forest, where they were lower than those under the native forest. However, levels of exchangeable cations and Bray-P in topsoils under radiata pine stands were higher than those of native stands. Concentrations of etherextractable components (lipids), water-soluble carbohydrates and polyphenols in the forest floors under native forest were generally higher than those under radiata pine stands. Consistent differences between concentrations of lipid components and polyphenols in the topsoil under native and exotic forest were not found.

Simultaneous TG, DTA techniques have been applied to investigate the combustion characteristics of Victorian brown coal derived from different coal fields and including various l!thotypes. TG and DTA profiles of the entire combustion process were obtained to provide a set ofpardmeters which characterize the oxidation potential of these coal samples. These parameters can also be used to predict the combustion performance of pulverized coal in industrial furnaces. The area of the major DTA combustion peak is closely related to the heat released during the combustion process and therefore provides a means of determining the specific energy of the coal. Different lithotypes are also characterized by their corresponding TG and DTA burning profiles.Thermal analysis techniques have been widely used in the study of coal combustion. It is known that for a range of fuels which have similar TG burning profiles, their performance in an industrial pulverized coal furnace is similar [1]. Thermal analysis data can be applied not only to the characterization of different Coals, but also to the evaluation of combustion performance at high temperatures and heating rates. Since only a small sample size is required in the analysis, the burning profile is most useful for evaluating the burning properties of fuel when only small samples are available or when it is impractical to test-fire large quantities of fuel in existing installations [2].In the present work the combustion performance of some brown coal samples and lithotypes of brown coat is investigated by simultaneous TG and DTA techniques.John Wiley & Sons, Limited, Chichester dkad~miai Kiadr~ Budapest

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The combustion of brown coal chars, obtained at different pyrolysis temperatures, have been investigated using TG, DTG and DTA thermal analysis methods. The burning profiles and the kinetic parameters derived from TG and DTA data show that all the chars are less reactive than the parent coal. The higher temperature chars have lower overall reactivity. From the corresponding infrared spectra, the chars obtained at 800"~ and I000 ~ appear to have graphitic structures.Victorian brown coal is a low rank, non-coking coal which produces a char during the pyrolysis process. Brown coal char is mainly used in the manufacture of acetylene for the plastics industry [1]. The properties of char depend on the conditions of pyrolysis via which it is produced.Thermal analysis offers an attractive and rapid method for the investigation of the char oxidation process. The DTA curve reflects the magnitude of the enthalpy change during combustion [5], and the TG and DTG profiles can be used to derive corresponding kinetic parameters [2][3][4][5][6][7][8][9][10].Several studies have been reported [2,4] on the reactivity of bituminous coal char using isothermal TG techniques. The results obtained by Khan [2] suggest that lowtemperature chars exhibit higher reactivity than the parent coal or hightemperature chars and that the oxygen chemisorption capacity is an important reactivity parameter. Patel et al. [7] studied the combustion rate of lignRe char by isothermal methcds. The activation energy obtained in the chemical rate controlled zone was 120 kJ/mol. Compared to isothermal analysis, non-isothermal analysis has some advantages [12]. One mass loss curve is equivalent to a large number of isothermal mass loss curves and only one sample is required. The kinetics of oxidation can be derived over the entire relevant temperature range.Victorian brown coal and char are highly reactive with oxygen. It is very difficult to use isothermal techniques to investigate the oxidation kinetics, because the John Wiley & Sons, Limited, Chichester Akad~miai Kiad6, Budapest