Substantiation of the parameters of open stoping mining method with abandonment of unrecoverable pillars

Abstract

Relevance. Developing inclined ore bodies of low and uneven thickness using mining systems with caving results in great losses and dilution, deteriorating the conditions for ore gravitation. As a consequence, it becomes necessary to slice the barren rock in the lying side to form slopes with the desired angle. There are also characteristic ore losses at the dead end of the drawing drift independent of the ore body thickness, therefore acquiring a significant role under a lesser thickness. The height of the sublevels, limited by the ore body’s inclination, leads to a considerable amount of preparatory and development operations. The absence of actual in-process monitoring of useful component content in the ore drawing doses often leads to increased dilution rates due to the drawing of barren caved rocks of the previously worked overlying sublevel. Thus, the technological solutions search and their design parameters substantiation for the conditions of inclined ore bodies of low thickness is an urgent scientific and technical problem. Research aim is to substantiate the parameters of the open stoping mining which provides for leaving unrecoverable pillars which ensure the drawing of the maximum volume of pure ore under the cantilever of the hanging side rocks. Research methods. The work used a comprehensive research method based on search and design of technically rational options for geotechnology, their technical and economic assessment and mathematical modeling, and determination of stable parameters of mining system structural elements – the chamber span and the pillar width. Results analysis. The optimal variant of the open stoping mining system has been determined. In comparison with the basic technology of sublevel caving, the specific consumption of preparatory and development operations per 1000 tons of mined ore has been reduced by 34%, the cost of mined ore – by 12%, and ore losses and dilution – by 2 and 2.9 times, respectively. The stable parameters of the chamber span and pillar width have been established. Conclusions. The developed technology of sublevel open stoping with double chambers with frontal ore drawing using remote-controlled loading and hauling machines and subsequent caving of unrecoverable pillars of minimum width allows to significantly increase the efficiency of mining.