Research on the Law of Low Oxygen in Working Face and Control Technology of Automatic Oxygen Spray

Low oxygen volume fraction during the mining process of the working faces can seriously endanger the safety and health of production personnel as well as influence the normal progress of the working faces. In response to the low oxygen problem under the current prevention and control measures in the 010901 working face of Hongshiwan Coal Mine, the low oxygen factors in the working face were investigated through monitoring the gas concentration distribution status of the working face and goaf. A method of combining oxygen spraying and air guide cloth to treat low oxygen in the corner of the working face return airway was proposed in the study. Fluent simulation software was used to investigate the distribution law of the oxygen volume fraction in the corner of the working face after using air guide cloth alone and adding oxygen spraying measures. A PLC control program was designed to associate the oxygen concentration monitoring system with the oxygen spraying device, and low oxygen prevention and control technology was applied on site to obtain automatic monitoring and control of low oxygen in the working face. The research results demonstrate that under constant air flow and no oxygen injection conditions in the working face, the oxygen volume fraction in the upper corner was less than 18.5%, failing to satisfy the occupational safety and health requirements of the working face. After adding oxygen spraying measures, the oxygen spraying device was located 6.5 and 3.8 m away from the upper corner of the working face and the ground, respectively. The upper limit of the outlet pressure was set to 2.8 MPa, which can satisfy the requirements of solving low oxygen problems. With the increasing outlet pressure of the oxygen spray, there was instability in the volume fraction of oxygen in the corners of the working face. When the outlet pressure reached 1.3 MPa, the oxygen concentration in the corners of the working face increased to 20% and remained constant and the oxygen spray device automatically shuts off. Moreover, this study also provides technical support for the prevention and treatment of low oxygen in the corners of the working face.