Pysmennyi S. Improvement of deep deposit underground mining technology for combined surface and underground mining.

The thesis deals with new approaches to current scientific and, technical and practical tasks of determining of losses and dilution, constructions and parameters of "floating" pillars (FP) that provide high indices of extraction when combined surface and underground mining of reserves under overburden dumps. Output cone diameter changes are proved to depend on diverse technological factors. The proposed construction of a "floating" pillar with protective ledges along its perimeter enables ore dilution reduction and FP integrity increase. FP thickness changes are determined to depend on the operating load. Efficiency of obtained results lies in loss and dilution reduction as well as in reduction of net costs for ore mining when combined surface and underground mining of reserves under overburden dumps.