Coal Fire Sublimates: Are We Missing Something?

Abstract

Uncontrolled coal fires present a nearly unparalleled environmental and human health disaster. These fires can cause the destruction of the ecosystem, ignite forest fires, become a source of windblown dust and siltation of streams, and pollute surface water, ground water, and crops. They can cause significant disruption of families and communities resulting from physical hazards of collapse or explosion, excessive heat, visual blight and loss of potentially valuable acreage, deterioration of cultural infrastructure, personal and public property, and loss of a valuable energy resource. The emission of CO2 and other greenhouse gases presents a significant health hazard due to respiration of dust and aerosols, and exposure to acidic gases, potentially toxic trace elements, and organic compounds. Numerous studies have described many dozens of phases that have condensed from the effluents of these fires. However, many of these studies may have overlooked the nano- and ultra-fine particles that exist beside, in, and under the brightly colored, often spectacular crystalline macro phases. Using a scanning electron microscope with an energy dispersive X-ray detector we examined a small (30 mm × 10 mm) piece of condensate from an uncontrolled coal fire in the Jharia region of India and found more than 30 different phases in this one small piece. The phases included ammonium, copper, iron, lead, bismuth chlorides; bismuth, lead, and ammonium silici-fluorides; ammonium and lead iodates; iron, barium, lead, copper, and zinc sulfides; iron and silicon oxides; and others. Broken fragments revealed multiple generations of phases. Though not strictly nanoparticles (smaller than 0.1 μm), many of these particles are in the micrometer to sub-micron range and it is likely that there are phases present in the nanoparticle size range. Certainly, particulates in the nanoparticle and ultra-fine particle range are being released from the uncontrolled coal fires and may be impacting the environment and the health of the mine workers and nearby residents, an issue that should be investigated.