The article deals with the development technologies of deep ore deposits with medium life cycle. These deposits are a promising source of raw materials for many Russian mining enterprises. The "upward" and "downward" technology of stripping and development of such deposits is proposed. The results of regime-deformation tests in the "up-down" technology and their comparison with the results in the "down-down" technology are given.
Modern stripping schemes for steeply dipping ore deposits are analyzed. Possible stripping schemes for ore body mining in the combined ascending-descending order of operations are designed. Dependences of the reduced costs on the depth of the first stage of stripping and the angle of dip of the ore body at the combined order of deposit development are established. Conclusions and recommendations are made.
The stresses at the edge of the ore massif at the ascending and descending order of deposit mining were compared. As a result of theoretical calculations, it was obtained that when working at deep horizons, the stresses in the ascending order are less than in the descending order.
The stress state of artificial monolithic pillars under the combined system of field development, which is affected by the rock pressure of hanging wall rocks and the active pressure of loose rock filling located in the chamber of the 2nd stage, was analyzed. As a result of calculations the optimum length of of the 1st stage chamber is 8 m, length of the 2nd stage II chamber is 40 m, hardening deposit strength is 3 MPa.
In the practice of development of ore deposits of non-ferrous metals, combined development systems are increasingly used. The horizon is divided into chambers of stages I and II, which differ in the type of stowing material used. The chambers of stage I are filled with solid stowing, and the chambers of stage II are filled with loose rock. The economic performance of the development system is largely determined by the ratio of I and II stage chambers, since the costs of solid and loose rock stowing are significantly different. In this order of works, the following geomechanical situation takes place: in addition to rock pressure, which loads the pillar from the hanging wall, there is lateral pressure of loose rock deposit on the pillar, which is a retaining wall. The pressure tends to destroy, overturn or move the pillar. Thus, the purpose of this work is to determine the dimensions of monolithic pillar retaining walls in conditions of complex simultaneous loading by rock pressure and active pressure of loose rock deposit when changing technological parameters of development system. A calculation scheme for determining the dimensions of artificial pillars is made, modern methods of calculating rock pressure are described and the width of the retaining wall is calculated when changing the strength of the monolithic deposit and the dip angle of the deposit.
The possibility of using the ascending order of mining deep horizons of the Zapolyarnoye deposit at the Severny mine of the Kola MMC instead of the currently used descending order of development system with sub-stage ore excavation and backfilling of the mined space with solid monolithic backfill is considered. It is proposed to switch to a two-stage development of chambers with the use of combined stowing in the ascending order of excavation within the entire field: solidifying monolithic stowing of the I stage chambers and rock stowing of the II stage chambers. Monolithic solid stowing serves as a retaining wall when excavating phase II chambers. Calculations according to the Coulomb theory allow us to consider the ratio of phase I and II chambers sizes equal to 1:7 to be expedient. Replacement of solid stowing with combined stowing, most of which is represented by rock, as well as transition to increased height of chambers will reduce the cost of extracted ore and improve the geomechanical situation in the host rocks.
All over the world, there is a tendency to develop high-capacity deposits using the combined open-underground mining method with a descending order of mining floors. The article proposes an ascending order of floors in the application of combined field development. The essence of the proposal under consideration is as follows: the deposit is stripped at once for the whole depth of development in steps of 240 m, where concentration horizons are located. Each level of stripping is divided into levels from 40 to 120 meters high which are developed in ascending order. The levels are divided into extraction blocks, which are mined by the level-camera system of development. Narrow chambers 5 m long are mined in the block in the first place and backfilled with low-strength hard fill. After that, the remaining reserves of the 35-meter long block are mined and filled with hydraulic rock fill from mining and overburden of the open pit. Application of rock and low-strength solid stowing makes it possible to reduce the cost of extracted ore in spite of considerable initial capital expenses for carrying out capital workings - shafts and concentration horizons. This study convincingly proves that the ascending mining sequence of deep deposits with combined deposit mining is more effective than the traditional descending mining sequence with the use of a solid stowing.
