NUMERICAL SIMULATIONS OF VORTEX PROCESSES IN DEEP OPEN PIT MINES AND THEIR INFLUENCE ON DUST SPREAD

Abstract

The use of powerful blasts during mining operations in open pit mines results in environmental pollution of the air both inside and outside the pit. The dynamics of wind interaction with the pit surface and the spread of blast dust are investigation by numerical methods. The vertical stratification of the flow in the area of space bounded by the pit sides into lower and upper zones of different vortex structures is demonstrated in a model setting (two-dimensional geometry, constant incoming stratified wind, model profile of a deep (500 m) open pit mine). It is shown that the temperature inversion region is formed inside the pit in the vicinity of the boundary between the zones. The propagation of the dust cloud formed by a powerful explosion on the bench of the windward side of a pit is investigated. It is shown that part of this cloud, initially located in the lower zone, is carried by vortex flows towards the opposite side and does not go beyond this zone, remaining inside the pit. The only way to clean the pit is by slowly flow of air escape along the top of the windward side. Dust from this pathway travels downwind along the surface, contributing to pollution in areas away from the pit.