Thermogravimetric analysis of selected coal-bearing strata kaolinite

Two kinds of coal-bearing kaolinite from China were analysed by X-ray diffraction (XRD). Thermogravimetric analysis-mass spectrometry (TG-MS), infrared emission spectroscopy. Thermal decomposition occurs in a series of steps attributed to (a) desorption of water at 68 degrees C for Datong coal-bearing strata kaolinite and 56 degrees C for Xiaoxian with mass losses of 0.36% and 0.51%, (b) decarbonization at 456 degrees C for Datong coal-bearing strata kaolinite and 431 degrees C for Xiaoxian kaolinite, (c) dehydroxylation takes place in two steps at 589 and 633 degrees C for Datong coal-bearing strata kaolinite and at 507 and 579 degrees C for Xiaoxian kaolinite. This mineral was further characterised by infrared emission spectroscopy (IES). Well-defined hydroxyl stretching bands at around 3695. 3679, 3652 and 3625 cm(-1) are observed. At 650 degrees C all intensity in these bands is lost in harmony with the thermal analysis results. Characteristic functional groups from coal are observed at 1918, 1724 and 1459 cm(-1). The intensity of these bands decrease by thermal treatment and is lost by 700 degrees C. (C) 2010 Elsevier R.V. All rights reserved.