Abstract
Several natural threats characterize hard coal mining in Poland. The coexistence of methane and rock-burst hazards lowers the safety level during exploration. The most dangerous are high-energy bumps, which might cause rock-burst. Additionally, created during exploitation, safety pillars, which protect openings, might be the reason for the formation of so-called gas traps. In this part, rock mass is usually not disturbed and methane in seams that form the safety pillars is not dangerous as long as they remain intact. Nevertheless, during a rock-burst, a sudden methane outflow can occur. Preventing the existing hazards increases mining costs, and employing inadequate measures threatens the employees’ lives and limbs. Using two longwalls as examples, the authors discuss the consequences of the two natural hazards’ coexistence. In the area of longwall H-4 in seam 409/4, a rock-burst caused a release of approximately 545,000 cubic meters of methane into the excavations, which tripled methane concentration compared to the values from the period preceding the burst. In the second longwall (IV in seam 703/1), a bump was followed by a rock-burst, which reduced the amount of air flowing through the excavation by 30 percent compared to the airflow before, and methane release rose by 60 percent. The analyses presented in this article justify that research is needed to create and implement innovative methods of methane drainage from coal seams to capture methane more effectively at the stage of mining.
Highlights
Taking the above into account, bumps with energy up to 104 J or higher do not pose a potential threat of rock-burst and a sudden outflow of methane
The natural hazards existing in mines often aggravate each other, increasing the risks to personnel working in excavations
Bumps with energy up to 104 J or higher do not pose a potential threat of rock-burst and a sudden outflow of methane
Summary
In the Upper Silesian Coal Basin’s coal measures—considering its area and hitherto identified layers—the presence of methane varies, and its distribution is very uneven [4,5]. The first peak of methane content corresponds to the presence of the impermeable overburden at a depth of 150–200 m below the carboniferous roof; it is caused by a high degree of metamorphism in the carboniferous formation. The first peak of methane content corresponds to the presence of the impermeable overburden at a depth of 150–200 m below the carboniferous roof; it is caused by a high degree of metamorphism in the carboniferous formation at a at a considerable depth, which had the following consequences: A greater degree of considerable depth, which had the following consequences: A greater degree of carbonicarbonification and a higher reduction in the amount of volatile matter, an increased amount fication and a higher reduction in the amount of volatile matter, an increased amount of of thermogenic methane in coal, reduced coal hardness and coal’s sorption capacity. Szczygłowice borehole; (b) description for borehole Dębińsko Głębokie 8 [9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
