Abstract
Mine ventilation has always been critical for underground mining operations to ensure operational efficiency and compliance with safety and health statutory requirements. To obtain a thorough understanding of the ventilation flow characteristics on a longwall face, innovative three dimensional (3D) models, incorporating key features of the longwall equipment and a zone of immediate goaf area, were developed. Mesh independent studies were conducted to determine the desirable mesh required for a mesh-independent solution. Then the model results were validated using field ventilation survey data. At both intersections of maingate/tailgate (MG/TG) and face where the flow boundary changes sharply, the occurrence of undesirable flow separation which causes additional energy loss was identified, as well as its extent of influence. The recirculation of airflow resulting from separation in the TG will lead to accumulation of high concentrations of mine gas, thus regular inspection or continuous monitoring of gas concentration in that area is highly recommended, especially when high gas emission is expected from the working seam. In addition, we also investigated the influence of shearer position and cutting sequence on longwall ventilation. Overall, the longwall models developed in this study together with the flow characteristics obtained will provide fundamental basis for the investigation of longwall gas and dust issues in the future.
Highlights
Longwall panels are typically 150 to 400 m wide and can be up to 3 to 4 km long, depending on the geological conditions
Toraño et al [35] carried out CFD studies to investigate the methane flow behaviour in a development heading of an underground coal mine, where both airflow and methane concentration were measured at selected cross sections and points for the validation purpose
To thoroughly understand the airflow patterns within the longwall face, two more models were constructed to probe the flow features under different longwall mining scenarios, which were achieved by positioning the shearer to the middle section and TG side of the longwall face respectively
Summary
Longwall panels (rectangular coal blockss to be mined) are typically 150 to 400 m wide and can be up to 3 to 4 km long, depending on the geological conditions. Similar to the excavation of tunnels and other underground facilities, ventilation to the longwall face is vital in terms of providing fresh air for operators and diluting hazardous gas/dust as well as cooling the mining machinery. The results can provide practical guidance to mine operators for improved longwall ventilation flow characteristics on a typical longwall face. Thethe longwall models developed in mine operators for improved ventilation management, gas/dust hazards prevention. Some of the major explosions that occurred recently in underground coal mines are ventilation [5,6,7,8]. Mine ventilation to the underground workplace is vital for diluting hazardous gas and dust contaminants. Better understandings on the ventilation system using more advanced techniques are needed to guarantee a safe and healthy working environment in the underground space
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