超长巷道炮掘时粉尘分布规律研究

摘要

In order to analyze the dust migration laws and guide the design of dust control system in long-distance blasting excavation roadway,based on the 1 100 excavation face in a metal mine,a 1∶1 geo-metric model is established to conduct the CFD simulation,to analyze the air flow field and boundary con-ditions.According to the model applicability and the air flow field distribution characteristics,the RNG k-εturbulence model is selected to simulate the air flow field in 1 100 excavation working face,the simula-tion results show the dust volume fraction in the blasting space is low than 10%,which determines that u-sing the discrete phase model to simulate the dust unsteady movement in the blasting space is suitable. The dust diffusion law,dust sedimentation law and dust concentration changing law are obtained in the scope of 0~60 m nearby the excavation face.The results show that the dust concentration decreases when the height increases from 0.5 to 4 m,and the dust concentration distribution has a obvious demarcation in the vertical direction,along the roadway,the dust concentration firstly increases and then decreases.The dust particle with the diameters under 10 μm is evenly distributed in the space,and the sedimentation quantity shows a trend of "decrease-increase-decrease-increase"along the roadway,while for the dust particles with diameters of 10~200 μm,the sedimentation quantity shows a trend of"decrease-increase-decrease".Dust particles with diameters of 15 ~200 μm almost completely settle.In the early blasting op-eration within 5 min,the dust concentration along the roadway sharply decreased,and gently decreases with 5 ~50 min.The high concentration area stays within 0~40 m and dose not migrate along the road-way.The migration laws show that 10~20 m is the air dust jet vortex area which strongly affects dust dif-fusion,sedimentation and concentration variation.In order to investigate the precision of the simulation re-sults,during the blasting period,the AKFC-92A Dust Sampler and the CCHZ-1000 Automatic dust detec-tor are set up at 20 m and 25 m to detect the dust concentration.The actual measurement values are basi-cally consistent with the simulation values,which indicates the simulation results is reliable.%为确定长距离爆破掘进工作面粉尘运移规律，以指导防尘系统设计，依托某矿1100掘进工作面，建立1∶1几何模型进行CFD模拟，测算空气流场和粉尘运动边界条件。根据湍流模型适用性和空气流场分布特征，优选RNG k-ε湍流模型模拟1100掘进工作面空气流场，算得空间内粉尘体积分数小于10％，因此选用离散相模型模拟爆破空间粉尘非稳态运动。最终获得距掘进面60 m范围内粉尘扩散、粒径沉降和浓度时间变化规律：粉尘浓度沿垂向分布有明显分界，浓度随垂高在0．5～4 m递增而降低，粉尘浓度沿纵向先升高而后降低；粒径为10μm以下粉尘均匀分布于空间，沉降量沿纵向呈“减少—增高—减少—增高”趋势，10～200μm粉尘则呈“减少—增高—减少”趋势，15～200μm粉尘几乎完全沉降；爆破后5 min内粉尘浓度急剧下降，5～50 min粉尘浓度下降缓慢，高浓度区长时间停留在距工作面40 m之内，不沿巷道运移；距工作面10～20 m形成的空气涡流区是影响粉尘扩散、沉降和浓度变化的重要因素。爆破期间在距工作面20，25 m处，分别采用AKFC-92A采样器和CCHZ-1000全自动粉尘测量仪监测粉尘浓度，实测值与模拟值基本相符，模拟结果可靠。