露天矿一般都采用自然通风.当露天矿的开采深度超过自然通风范围时需采用人工通风.自然通风的范围按自然风流的自由扩散角α_2来确定(图1).α_2角受风速、地形、空气下垫面和季节的影响,冬季和夏季有差别,一般为8°～10°.另外,由于自然风流的风速在露天采场内的衰减,一般采深150m以上的露天矿靠自然通风已存在困难.如我国某露天煤矿坑底处(采深280m)的静风概率为:白天12.1%,夜间37.40%,全天平均28.9%(1980年1月的资料).位于东经61°、北纬55°的 Open-pit mines generally use natural ventilation. When the mining depth of open-pit mines exceeds the natural ventilation range, artificial ventilation is required. The range of natural ventilation is determined by the free diffusion angle α_2 of natural wind (Figure 1) Air surface and the impact of the season, there are differences between winter and summer, usually 8 ° ~ 10 °. In addition, due to the natural wind speed in the open pit decay, the general mining more than 150m open pit by natural ventilation has been Such as the pit at the bottom of an opencast mine (mining depth 280m): 12.1% during the day, 37.40% at night, an average of 28.9% throughout the day (January 1980 data) 55 °