58 GeoLines 22 2009 Bituminous Coals Thermodestruction by the Thermofiltration Method Vladimir SAFIN 1 , Ludmila BUTUZOVA 1 , Stefan MARINOV 2 and Natalia YANEVA 2 1 Donetsk National Technical University, 58 Artema str., Donetsk 83000, Ukraine 2 Bulgarian Academy of Sciences, Institute of Organic Chemistry, Acad, G. Boncheva str. blgd. 9, Sofia-1113, Bulgaria ABSTRACT: Coking coals of the same rank but different genetic types (reduced and low-reduced) have been studied by means of coal chemistry. It has been shown that reduced coals and low-reduced coals are distinguished by composition, structure and thermal behavior. These facts have been explained with various associations of high-condensed aromatic blocks in coal macromolecules. KEY WORDS: coking coals, genetic types by reductivity, thermofiltration, coal structure. Introduction Coal properties depend not only on the coal rank. Some coals of the same rank and the close petrographic composition but with aberrant properties occur in the same coal field. Abnormal coals have been found in the Durham and the Ruhr coal fields, the Donetsk and the Kuznetsk basins (Murchison and Pearson 2000, Amosov 1963). Such coals are called reduced (RC) and low-re- duced (LRC) type or perhydrous and subhydrous coals in com- pliance with monograph (van Krevelen 1981). But both of cat- egorizations are not the same. The genetic type by reductivity refers to geological characteristics of coal seams and indicates conditions of peat-forming plants decomposition. The presence of limestone layers above the coal seams, and finely crystalline pyrite within them proved to be reliable signs of a reduced type of Donetsk coals (Bechtet et al. 2002). According to the literature and previous investigations, RC and LRC of the same rank differ by following: composition of coal organic mass (COM), H/C (atm.) (Butuzo- va et al. 2005a, Butuzova et al. 2002) some special feature of COM structure (Butuzova et al. 2005b, Iglesias et al. 2002) coking ability (Butuzova et al. 2005b) yields of pyrolytic products, their composition etc. (Murchison and Pearson 2000, Iglesias et al. 2002, Butuzova et al. 2005a, Butuzova et al. 2002). But these facts have been interpreted from the position of RC and LRC structures. The structure and reactivity of the different genetic coal types have not been well studied till now. The thermofiltration method was used for present investiga- tions. This thermal method has large potential for study of cok- ing coal structures, transformations of their organic mass under heating. The thermofiltration make possible to save nonvola- tile components of a coal plastic layer and to study last one by different methods such as an extraction, chromatography and FT-IR spectroscopy. The main aim of the present study was investigation to ob- tain more information concerning of GTR influence on a yield of pyrolytic products, a conversion of heated coking coals orga- nic mass and a composition of coal plastic layer. Procedures Representative coal samples from Donetsk Basin were used in this study. Two pairs of reduced and low-reduced coking coals were selected from closely spaced coal seams separated by dis- tances of less than 100 m. (Geological-geochemical map 1954). The geological factors were used for identification of genetic types by reductivity of selected coals. All coals were character- ized as a petrographic homogeneous. Middle content of vitrinite was about 85 % (Table 1). The samples were analyzed accord- ing standard procedures; the thickness of plastic layer by Sa- pozhnikov’s method (Y) was applied as characteristic of coal coking ability. The ultimate and proximate analyses of investi- gated coals are shown in the Table 2. The thermal decomposition of coals was carried out by the termofiltration procedure (GOST 17621-72). The last one is based on centrifugation of a coal sample with simultane- ous quick heating up to 600 °C. This technique allows separat- ing nonvolatile components of a plastic mass without second- ary thermal transformation from a remaining COM which does not be able to transform to a plastic layer. The termofiltration process was realized in the centrifuge which was constructed in Kharkov Polytechnic Institute (Birukov 1980). The nonvola- tile components (LNP) accumulated in a cold collector; the non- transformed residue of COM (NTR) stayed on the metal filter; the volatile matters exuded through a gap between the collector and the metal filter. The experimental conditions: speed of the № Coal mine, seam Type R о,r [%] Petrographic components [% vol.] Lithotype with finely crystalline py- rite [% vol.] Vt L I 1 Gagarino m 3 LRC 1.18 85 3 12 1 2 Zasiadko l 4 LRC 1.01 89 6 5 0 1 ' Gagarino m 4 0 RC 0.96 87 3 10 82 2' Zasiadko k 8 RC 0.96 83 3 14 56 R о,r – vitrinite reflectance, Vt – vitrinite, L – liptinite, I – inertinite. Tab. 1. Vitrinite reflectance and petrographic composition of the sampled coals.