Abstract
Coal basically consists of two parts—a crystalline, inorganic part, and an amorphous, organic part. Based on this, we intended to study the changes that occurred on the composition and on the chemical structure of coals after carbonization at 1000 or 900° C and demineralization treatments with hydrochloric and hydrofluoric acids. For this, four coals of different categories (or levels) were chosen: semianthracite (A-O) and high volatile bituminous coal (B-O), which are high level coals, and lignite (Li-O) and leonardite (Le-O), these being low level coals. The coals were first analysed in terms of their proximate and elemental compositions and then carbonized and demineralized. Also, the starting coals and the prepared samples were examined by infrared spectroscopy. In addition, a study of the optimization of the application of this technique for only A-O was carried out. For A-O and B-O, the spectra recorded intense absorption bands that are ascribable to vibration modes in mineral components as quartz and aluminosilicates, such as kaolinite. For Li-O and Le-O, the spectra displayed some other bands as well, also quite intense, which have been assigned to bond vibrations in functional groups and structures of their organic part. The carbonization of the coals resulted in significant changes in their inorganic part as the content of quartz increased and the content of aluminosilicates decreased. In addition, the thermal decomposition of mineral carbonates occurred. The carbonization greatly affects the organic part of the coals, especially in Li-O and Le-O, as most functional groups and structures are not thermally stable under heating conditions. With regard to demineralization, HF is a more effective agent than HCl, achieving products with higher organic content. The mass losses are higher in Li-O and Le-O than in A-O and B-O. So, the infrared spectroscopy allows the analysis of both inorganic and organic parts of the coals and of their carbonization and demineralization products. These processes facilitate subsequent analysis of the inorganic and organic parts of coals by infrared spectroscopy. In the application of this technique, both the coal: KBr ratio and the thickness for the disks should be controlled, owing to the influence on the infrared absorption.
Similar content being viewed by others
References
Alfaro-Domínguez M, Híges-Rolando F J, Gómez-Serrano V, Martín-Aranda R M, Rojas-Carvantes M L and López-Peinado A J 1998Energy & Fuels 12 289
Berkwitz N 1987Am. Chem. Soc. Adv. Chem. Ser. 217 217
Brand J C D and Eglinton G 1965Applications of spectroscopy to organic chemistry (London: Oldbourne Press)
Büchner W, Schliebs R, Winter G and Büchel K H 1989Industrial inorganic chemistry (Weinheim: VCH)
Carlson D A 1991Int. conf. coal sci. (Oxford: Butterworth-Heinemann) p. 2427
Carlson G A and Grannoff B 1991Am. Chem. Soc. Symp. Ser. 461 159
Chester R and Green R N 1968Chem. Geol. 3 199
Davidson RM 1982Coal science (eds) ML Gorbaty, JM Larsen and I Wender (New York: Academic Press) Vol. I, p. 83
Dixon J B and Weed S B (eds) 1979Minerals in soil environments (Madison: Soil Sci. Soc. of America)
Farmer VC 1974The infrared spectra of minerals (Londres: Mineralogical Society)
Gavalas G R 1982Coal pyrolysis (Amsterdam: Elsevier)
Given P H 1960Fuel 49 147
Given P H 1976The organic chemistry of coal materials. Short course on coal characteristics (University Park, PA: Pennsylvania State University)
Given PH 1984Coal science (eds) ML Gorbaty, JW Larsen and I Wender (New York: Academic Press) Vol. 3, p. 63
Gómez-Serrano V, Pastor-Villegas J, Pérez-Florindo A, Durán-Valle C J and Valenzuela-Calahorro C 1996J. Anal. Appl. Pyrol. 36 71
Gorbaty M L 1994Fuel 73 1819
Grainger L and Gibson J 1981Coal utilization: Technology, economics and policy (Londres: Graham & Trotman)
Green T, Kovac J, Brenner D and Larsen J W 1982Coal structure (ed.) R A Mayers (New York: Academic Press) p. 199
Herzberg G 1945Infrared and Raman spectra of polyatomic molecules (New York: D. Van Nostrand)
Hüttinger K J and Mchenfelder A W 1987Fuel 66 1164
Inventario de recursos de carbón en España 1979Centro de Estudios de la Energía, Ministerio de Industria y Energía, Madrid
Jankowska H, Swiatkoswski A and Choma J 1991Active carbon (New York: Ellis Horwood) p. 89
Kovac J and Larsen J W 1997Am. Chem. Soc. Div. Fuel Chem. 22 181
Larsen J W and Kovac J 1978Am. Chem. Soc. Symp. Ser. 71 36
Lucht L M and Pepas N A 1987Fuel 66 803
Manahan S E 1994Environmental chemistry (Boca Raton: Lewis Publishers)
Marzec A 1986Fuel Process Technol. 14 39
Muntean J V and Stock L M 1991Energy Fuel 5 767
Radamacher W and Hovernath A 1959Brennst. Chem. 40 97
Retcofsky H H 1975Fundamental organic chemistry of coal (USA: University of Tennesse)
Rouzaud J N 1990Fuel Process Technol. 24 55
Solomon P R 1981Am. Chem. Soc. Symp. Ser. 169 61
Solomon P R, Hamblen D G, Carangelo R M, Serio M and Deshpande G V 1988Energy Fuels 2 405
Spackman W 1958 Trans. New YorkAcad. Sci. Ser.II 20411
Speight J G (ed.) 1990Fuel science and technology handbook (New York: Marcel Dekker, Inc)
Spence J A and Vharman M 1970Fuel 49 395
Unsworth J F, Barratt DJ and Roberts PT 1991Coal quality and combustion performance. An international perspective (Amsterdam: Elsevier)
Van der Mare H W and Beutelspacher H 1976Atlas of infrared spectroscopy of clay minerals and their admixtures (Amsterdam: Elsevier)
van Heek K H, Strobel B O and Wanzl W 1994Fuel 73 1135
van Krevelen D W 1981Coal (Amsterdam: Elsevier)
Vharman M 1970Fuel 49 5
White J L 1971Soil Sci. 112 22
Wiser W H 1973Proc. EPRI conf. coal catalysis (CA, Palo Alto: Conference Coal Catalysis) p. 3
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Gómez-Serrano, V., Fernández-González, M.C., Rojas-Cervantes, M.L. et al. Carbonization and demineralization of coals: A study by means of FT-IR spectroscopy. Bull Mater Sci 26, 721–732 (2003). https://doi.org/10.1007/BF02706770
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02706770