Modelling of Aerodynamic Process for Coal Waste Dump Located in Geodynamically Dangerous Zone

Abstract

Previously made evaluations show confinement of fire coal waste dumps to geodynamically dangerous zones which in this work are considered as borders of active blocks of the earth crust. According to the hypothesis under development, when disposing the dumps in geodynamically dangerous zones (GDZ), which have a high penetrating, aerodynamic relation of the dumps with the environment occurs, making the dumps firing possible. Firing of the dumps inflicts environmental, social and material damage. This research is aimed to study possible mechanism of gas mass transfer through GDZ into the body of dump on the base of computer modeling of aerodynamic processes. A relevant geometry model is developed, borderline conditions are proven and modeling of aerodynamic process is shown in the work. Taking into account actual data on location and characteristics of firing dumps of a region of Eastern Donbas (Rostov region, Russia) calculation are performed by means of ANSYS software. A dump located in GDZ is modeled. The GDZ is set in the model as a highly penetrating linear zone in the rock, which has a deep emplacement. The GDZ crosses mine fields and has an expression in relief of the Earth surface. Temperature of the rock within the dump may reach 420 degrees Centigrade. Petrophysical characteristics are taken into account in the model (porousness and permeability) of its main structural elements, dimensions of the dump, width of GDZ, difference of relief heights, depth of mine workings location under the dump. The results of the modeling show influence of the dump temperature, petrophysical characteristics of the model structural elements, depth of the mine openings location on aerodynamic processes within the dump mass. Operability of the model at the preset border conditions allows to deeply argue the hypothesis of the air intake into the dump body with consideration of the local geodynamics. According to the results obtained, geodynamic conditions of mining area where coal waste dumps are disposed, may be and are an important factor, which has an effect on creation conditions for spontaneous combustion of dumps and its further impact on environment.