The properties of Çan Basin coals (Çanakkale—Turkey): Spontaneous combustion and combustion by-products

• This is the first detailed study about the susceptibility of Çan coals to spontaneous combustion and their products.
• The concentrations of the gas components formed by combustion were investigated.
• The mineralogical variations of burning coals were investigated.

The goals of this study were to investigate the susceptibility of Çan Basin (Çanakkale—Turkey) coals to spontaneous combustion and to determine the composition of the gas produced from the coal during combustion. Coal properties were determined using burned and partly burned coal samples; gas samples were analyzed for their composition. The mineralogical variations of burning coals were also investigated. Our results indicated that the pyrite content of Çan Basin coals is a significant factor for promoting combustion in addition to rank and moisture. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses indicated that the coal samples contained pyrite, quartz, cristobalite, tridymite, kaolinite, amorphous matter, and gypsum. Fumarolic minerals (sulfur blooming and ammonium chloride) forming on the surface of coal seams were monitored. Elements including beryllium, fluorine, scandium, vanadium, cobalt, nickel, copper, zinc, arsenic, selenium, zirconium, molybdenum, tungsten, mercury, tantalum, lead, and uranium were found to be higher in Çan coal samples than the world average. The concentration of arsenic (max. 3319.7 μg/g) was relatively high and is the major hazardous element in the region.Gases emitted from coal-fire vents in Çan coalfields were found to consist of a complex mixture of hydrocarbons, greenhouse gases, and toxic concentrations of carbon monoxide (CO), hydrogen sulfide (H2S), and benzene. Hydrocarbon concentrations ranged from 77 to 92%, and the dominant hydrocarbon gas was methane. Ethane (0.3 to 2.1%) and propane (0.2 to 1.4%) were also detected. Hazardous compounds such as 5-methyl-3-propyl-1,2-oxazole (C7H11NO), ethanediimidic acid, 1,2-dihydrazide (C2H8N6), and 2,3-dihydrofuran (C4H6O); high concentrations of nitrogen (N2) (max. 6.8%) and carbon dioxide (CO2) (max. 18.2%); and low concentrations of carbon monoxide were also determined. Greenhouse gases (CO2 and methane (CH4)) from burning coal beds may contribute to climate change and alter ecosystems. Gas components including furan, H2S, CO, carbon disulfide (CS2), benzene etc., can be hazardous to human health, even in trace amounts. As a result, the uncontrolled release of pollutants from burning coal beds presents potential environmental and human health hazards.