METHOD FOR PREPARING BLOCK BOTTOMS Russian patent published in 2023 - IPC E21C41/22 E21D9/02 

FIELD: mining.

SUBSTANCE: invention relates to the mining industry and can be used in systems with caving. The method for preparation of block bottoms includes carrying out haulage workings - drifts, entryways from them, drilling workings located between haulage workings - drifts at the level of the roof of the latter, formation of outlet windows by breaking holes of adjustable depth and direction from the borehole directly above the entryways with the formation of an obtuse angle of conjugation of the window edges and the entryways, the formation of rounded pillars, the connection of the outlet windows with the drilling working. The entryway is passed without a horizontal section directly from the haulage working - drift to the lower corner of the drilling working, without straying from it, and the entryway is given a wedged shape, the soil of the entryway is inclined at the angle of the repose slope of the crushed ore. To extract the crest of the enriched ore of the "dead" zone, before the collapse of the block, a perforated pipe is laid on the soil of the drilling working and connected to the mine networks of water and compressed air; at the final stage of the ore drawing from the block in the upper part of the entryways the limit roofing is installed preventing from ore discharge, water with compressed air is supplied to the base of the ridge, it is saturated with water and, under the influence of an air jet, the angle of internal friction of the ore is reduced, while creating impulses of concussive explosions of overhead charges laid on the soil of the entryways. As a result, the lower layer of the ridge is squeezed out by the weight of the rock mass column into the flow zone and is extracted through the open part of the entryways. The second layer falls in place of the first layer, and so on. According to expert assessment, this method can extract up to 65-70% of enriched ore from the crest of the "dead" zone with acceptable dilution.

EFFECT: reduction of cutting operations and the elimination of the enriched ore losses during the development of ore bodies with wedged mineralization.

2 cl, 3 dwg