Geomechanical and geotechnical features of rib pillar extraction in the korobkovo iron ore deposit

Temporary conservation of iron ore reserves in rib pillars in the Korobkovo deposit determines the need for advance strategic justification of their extraction taking into account the geomechanical state of the geotechnical system as a whole. The implemented analysis of geological and geomechanical conditions in the Korobkovo deposit shows that the high elasticity of rocks, high lithological variety, tendency of ferruginous quartzites to accumulate elastic strain energy, tectonic horizontal stresses present in rock mass as well as the concentration of the vertical and horizontal stresses in the pillars dictates a special attention to be paid to the stress-strain analysis of rock mass at different stages of mining. The most promising scenario of the rib pillar extraction on levels-71/-125 and-160/-250 m is higher stopes to 180 m high, with movable equipment at the stage of blasting and with self-propelling equipment in loading and handling of ore. The geomechanical analysis of the natural and man-made masses during stoping on level-160/-250 m after complete extraction of ore reserves on level-71/-125 m indicates that failure of rock mass in mining phase I is unlikely. The geomechanical assessment shows that the priority sequence of mining is extraction of the rib pillars from the panel center toward the interstall pillars. The rib pillar extraction in the Korobkovo iron ore deposit should be accompanied by the stress-strain monitoring and requires reliable justification of the stability and safety of the waterproof strata and all support structures at all stages of the field development. © 2020, "Ore and Metals" Publishing house. All rights reserved.