COAL FIRES BURNING OUT OF CONTROL AROUND THE WORLD: THERMODYNAMIC RECIPE FOR ENVIRONMENTAL CATASTROPHE

In major coal producing countries, including China, the USA, Russia, India, South Africa, and Great Britain, coal seams and waste piles are on fire. Some seams in China have been burning for over two hundred years! Fires often start in the abandoned workings or workings of a coal mine. Fires in abandoned workings are the most problematic. Major causes of fires include cutting and welding with torches, explosives, electricity, cigarettes, ignition of mine gas, surface fires transmitted to underground seams, and spontaneous combustion. Mine fires produce environmentally catastrophic effects ranging from the emission of poisonous asphyxiating gases into the atmosphere to condensation products that pollute streams and soil. Minerals condensed from burning coal form as gas exhaled from surficial vents and cracks, waste piles, and surficial coal seams cools and condenses. The exhalation-condensation process is analogous to the way minerals form in fumarolic environments. Common gases associated with coal fires are carbon monoxide (CO), carbon dioxide (CO₂), hydrogen (H₂), nitrogen (N₂), oxygen (O₂), hydrogen sulfide (H₂S), oxides of sulfur (SO_x) and nitrogen (NO_x), and various hydrocarbons including methane (CH₄). Minerals condensed from coal gas indicate that a variety of other gases are produced during combustion. Using thermodynamic loop (TL) analysis, it is possible to calculate P-T stability diagrams for gaseous condensates including orthorhombic sulfur (S), selenium (Se), and galena (PbS). The significance of the P-T diagrams is that they reveal environmental conditions that tend to favor the condensation of gaseous exhalations as opposed to the absorption of those exhalations into the atmosphere.