The authors describe the results of leaching of Cu, Ni, Fe and S from copper–nickel ore mill tailings. The lab-scale testing conditions simulated in-situ capillary rise of solutions to ground surface. The leaching agents were water and water solutions of hydrogen peroxide at concentrations of 0.5, 1.0 and 10.0
The article studies a mining system with stoping under open pit bodies at steeply dipping ore bodies of small and medium thickness using rubble concrete and dirt fill as ground control. The technology assumes upward mining on the levels at the total downward sequence of stoping. The limit variant of stoping in various geomechanical conditions is studied for a geotechnical situation of mining on three levels including two mined-out levels. The mining system parameters are substantiated using 3D FWEM-based mathematical stress–strain modeling. The dependence is revealed between the geotechnology parameters and the stress behavior, and between the stability of rocks in the structural components of mining and in adjacent rock mass. The areas of possible rock fracture are identified. The safety of the mining system is governed by the integrity of rubble concrete pillars and by the stability of the crown pillar.
The generalized stress deviator is introduced as a difference between a stress tensor and a unit tensor multiplied by an average normal stress non-reducible to an octahedral normal stress in a general case. From the condition that the average normal stress of the generalized deviator should be identically equal to zero, a functional equation of the relative average normal stress is obtained. The solution of the equation is given; it depends on one of the functions of two variables. The class of the limiting state criteria formulated relative to the relative average normal stress and the second invariant of the generalized stress deviator is discussed. It is shown that the von Mises–Schleicher and Mohr–Coulomb criteria belong in this class. Some intermediate cases are also discussed.
The accomplished review of the geological and geomechanical conditions at the Tashtagol and Sheregesh deposits shows that the operating mine fields contain small- and medium-amplitude fractures, faults, dikes and ore–rock interfaces. It is revealed that during heading and stoping, geodynamic phenomena arise mostly in the neighborhood of these planes of weakness. The mathematical modeling was used for the stress–strain analysis of rock mass at different slope angles of faults approached by development headings. It is found that in case of a fault 1 to 3 m wide, the shear of the fault edges along the fault plane at the fault slope angle of 65° can happen when an approaching roadway is at a distance not less than 10 m, at the slope angle of 45°—at a distance not less than 20 m and at the slope angle of 15°—at a distance not less than 40 m. For the faults 5 to 10 m wide, at the fault slope angle of 65°, no shearing takes place, at the slope angle of 45°, shearing can happen when a roadway approaches the fault at a distance not less than 5 m and at the slope angle of 15°—not less than 30 m.
The article describes the lab-scale tests of permeability of long-flame coal from the Mokhovsky Coal Mine in Kuzbass depending on the intensity of cyclic treatment of coal with liquid nitrogen. The freezing effect on jointing was assessed by the change in the gas flow and in the ultrasound velocity. It is found that permeability of the test coal in compression rises up to commercially significant values. To reach this effect, it is sufficient to implement three–four cycles of treatment with liquid nitrogen. The treatment decreases the ultrasonic P-wave velocity by up to 6
