| During the process of drilling, blasting and mucking, the tunneling section would generate large amount of dust, which is listed as one of the top five disasters in underground mine. The safety of mine production and the health of mineworkers are seriously threatened by the dust pollution. What’s more, the special conditions of hypoxia in high altitude area causes severe increasing of dust and significantly reducing the labor efficiency, therefore, the dust hazards in high altitude mine is more serious. To solve the dust concentration problem in high altitude mine, taking 4470m tunneling section of Jiama polymetallic ore in Tibet autonomous region as the engineering background, using theoretical analysis, site measurement and comparative analysis, numerical simulation and field test to study the dust distribution and the effect of ventilation. The main research work includes:According to gradient transportation theory, the dust diffusion model of multi-source dust was built at the tunneling section. Based on the theory of gas-solid two-phase flow, the stress situation of the dust particle was analyzed, the expression of the sedimentation velocity of high altitude tunneling section was deduced by the dynamic sedimentation equation and the eventually sedimentation velocity of different sizes of dust were calculated.Based on the field survey of workers in mining area, the changes of oxygen content, heart rate, blood oxygen saturation and other parameters were studied, the variation of human respiratory rate was analyzed and the correction index of the high altitude dust concentration was calculated. Based on the monitoring of dust concentration in tunneling roadway, the dust migration regularity under various dust sources while drilling and mucking operation was analyzed in different parameters and different roadway environment.The wind flow and the dust concentration between the forced ventilation and the far-pressing-near-absorption (FPNA) ventilation were analyzed by the comparative experiments to demonstrate FPNA ventilation was superior, while the optimal ventilation parameters of FPNA were determined by the comparative study.Based on the gas-solid phase flow theory, a 3D numerical model of dust movement in excavation roadway was established to simulate the forced ventilation and FPNA ventilation. GAMBIT was used for building the geometry and meshing, FLUENT was used for simulating two kinds of ventilation to explore the differences in dust removal efficiency and the reduction of dust concentration between two kinds of ventilation, the optimal value of the main parameters affected FPNA ventilation was also verified by simulation.As for the dust generation features of multi-source dust in excavation roadway of Jiama mine, the ventilation shunt model was designed based on FPNA ventilation, the optimal parameter of ventilation shunt was ascertained by numerical simulation method. The application effect of the ventilation shunt model was demonstrated according to the field test of dust removal efficiency. |
