Mercury emission from underground coal fires in the mining goaf of the Wuda Coalfield, China

Mineralogical and Chemical Characteristics of Coal Ashes from Two High-Sulfur Coal-Fired Power Plants in Wuhai, Inner Mongolia, China

“…The Wuda Coalfield is ~10 km long (N-S) and 3-5 km wide (W-E), with a total area of ~35 km 2 . There were approximately 27 coal seams (with a total thickness of 43 m) deposited in the Upper Carboniferous Taiyuan Formation and the Lower Permian Shanxi Formation [36]. The major coal-bearing Taiyuan Formation contains five coal seams (Nos.…”

“…9, 10, 12, 13 and 15), with variable total sulfur contents (0.88%-3.46%) and ash yields (13.10%-23.92%) [35]. The Wuda District borders the Gobi Desert in the west and north, and it borders the Yellow River and Ordos Loess Plateau in the east [36], which is divided into four zones: coal mine area (Wuda Coalfield), industrial park, urban area, and farm land [37]. The Wuda Coalfield is exploited by the Suhaitu, Huangbaici, and Wuhushan Mines ( Figure 1B).…”

“…The Wuda Coalfield is exploited by the Suhaitu, Huangbaici, and Wuhushan Mines ( Figure 1B). It is estimated that the coalfield has a total coal reserve of ~600 Mt, and it mostly produces bituminous coals used for industrial coking [35,36]. [33]; Liu [34]; and Dai et al [35]) (1, Wuda Coalfield; 2, Helanshan Coalfield; 3, Hengcheng Coalfield; 4, Weizhou Coalfield; 5, Weibei Coalfield; 6, Hedong Coalfield; and 7, Junger Coalfield) (A), and the division of Wuda District, Wuhai City, Inner Mongolia (modified after Cao et al [37]) (B).…”

Atmospheric Mercury Isotope Shifts in Response to Mercury Emissions from Underground Coal Fires

“…Even higher gaseous Hg concentrations, with an average value of 4165 ng m –3 , were reported in 2015 for emissions from monitoring boreholes that penetrated underground coal fire zones . We revisited the Wuda Coalfield in 2018 and found that the average gaseous Hg concentrations had decreased to 49 ng m –3 in the monitoring boreholes, 7 ng m –3 in the peripheral area, and 4.2 ng m –3 in the urban area . This demonstrates that the coal fire suppression projects were likely effective in controlling the development of coal fires and thus reducing coal fire Hg emissions to the atmosphere.…”

Experimental Investigation on Using Chloride/Hydroxide Aerosol to Control Spontaneous Combustion of Lignite in Underground Coal Mines

“…It is also characterized as a complex, dynamic, non-linear, self-accelerating process. − Many scholars have investigated the characteristics of the spontaneous combustion of coal from different perspectives to develop methods to inhibit or control the spontaneous reaction. , For instance, Zhao et al , explored the correlation of the functional groups and exothermic characteristics of bituminous coal during high-temperature oxidation. The most common disaster in underground coal mines is the spontaneous combustion of residual coal in goafs. ,, Much residual coal, broken rock blocks, and relatively closely-spaced material in goafs make it difficult to locate any fire source therein. , The main fire-extinguishing technologies used in underground goafs are grouting, sealing, plugging, inert media injection, etc. − Unfortunately, these technologies have excellent mine-fire extinguishing effects only when the mining, ventilation, and geological conditions are relatively simple. Consequently, under complex conditions, management of spontaneous coal combustion remains a challenge. − During fires in goafs with large seam dip angles, inert liquids such as mud colloids are injected; however, these materials are susceptible to flow under gravity and thus cannot remain in a fixed area for long periods, which results in the loss of fire extinguishing material and poor performance. − In addition, injecting a large amount of inert gas into the goaf will reduce the content of O 2 in a limited space.…”