Oxidation of Pokrovskoe coal in laboratory and natural conditions. 1. Kinetics of oxidation and technological properties

Abstract

The oxidation of coal from the Pokrovskoe mine consists of stages of initial and intense oxidation in both laboratory and natural conditions. The oxidation temperature has a significant influence on the properties of the coal. In laboratory oxidation, the surface layer of the coal grains is significantly modified, with loss of plastic-viscous properties and reduction in ignition temperature. In addition, at different temperatures, different chemical processes will predominate. The oxidation of Pokrovskoe coal is assumed to result predominantly in peroxide formation in natural conditions (from –1 to 22°C), whereas oxidation in a drying chamber (at 140°C) is accompanied by decomposition of the peroxides and the formation of coal-oxygen complexes. Hence, the oxidation of coal is different in laboratory and natural conditions, and correspondingly the change in technological properties of the coal will be different. The rate constants, the preexponential factors, and the activation energy for the oxidation of Pokrovskoe coal are calculated by methods developed in physical chemistry. The rate constants of oxidation are k0–1 = 0.0041 × 10–4 and 2.7933 × 10–4 min–1 in natural and laboratory conditions, respectively; the corresponding values of the preexponential factors are k0 = 266.0 and 267.8 min–1. In the range 7.3–140°C, the activation energy is Ea = 11.3 kcal/mol.