Home – Home – Jornals – Journal of Mining Sciences 2015 number 2

Obtained in underground excavation in Tashtagol Mine, Kemerovo Region, and in dislocation area in karst in Iskitim marble quarry, Novosibirsk Region, the experimental data give evidence of the change in the velocity of seismic wave packets depending on energy of mechanical impulse inputs when elastic waves propagate in the system of mineral body-fault zone-mineral body. It is shown in the article that the resulting dependences between first arrivals of seismic wave packets and energy of impact (source) conform with the kinematic relationship typical for pendulum waves in high-stress structured geomedia.

Based on the approach using the method of splicing asymptotic expansions with the retention of only the dominant term of the asymptotics, in plane deformation conditions, the authors model stress state of rock mass with the horizontal daylight surface and a horizontal bed with a long slot-like excavation. The rock mass is assumed elastic, uniform and isotropic, whereas the bed undergoes elastic and, then, elastoplastic deformation. In the latter case, the length of the face zone of plastic deformation is supposed to exceed the bed thickness and to be less than the length of the excavation.

The authors analyze seismo-thermal effect (STE) that is the internal heating of ground under the action of external vibration and impulse mechanical oscillation within a frequency range from units to hundred of hertz. It is found the STE has some general features such as “fatigue,” relaxation and freezing. The article reports long-term temperature monitoring under a platform of a periodically actuated vibration source. The empirical relationship for the level of STE and the depth below the vibration source platform is offered, and the interconnection of the STE level and the vibration power is shown.

The authors describe calculation of rock failure around breakage headings in coal mines based on two-dimensional problem of the theory of creep with high deformation. The case of non-ring induced disintegration of rocks and the influence of mine-geological parameters are illustrated.

The principles and findings of the research of the modern stress-strain state in the top layer of the crust within the Amur lithospheric plate. The integrated geomechanical assessment of ground conditions uses the method of the remote sensing. The authors demonstrate information content of the offered approach to different scale data analysis aimed at either assessment of regional stress state, or at refinement of non-tectonic features in the zones of localization of rockburst-hazardous mineral.

Retaining walls are often built in unsaturated soil at shallow depth above groundwater level. It is critical to define active pressure of the unsaturated soil for designing retaining walls, based on the expanded theory of lateral pressure by Rankin, considering interaction between active pressure and absorption of soil. For unsaturated floury soil occurring above groundwater level for a long time, the angle of internal friction is estimated based on the moisture content-absorption curve, for various depths of retaining walls and different values of absorption, which is constant and decreases with depth, the active pressures and critical height are determined for foundation pits with vertical unsupported walls. The results confirm that absorption reduces active pressure on a retaining wall and the critical height of the vertical walls of the foundation pits can be increased when absorption grows.

The developed pattern of calculation for the parameters of drilling and blasting in boreholes and shot holes is based on a charge design with reduced amount of explosive at the top. The calculation takes into account the action time of the explosion-generated pulse conditioned by outflow of detonation product gases. The authors have derived relations for such rational parameters of drilling and blasting that minimize costs for drilling at the same quality of rock fragmentation.

The authors analyze stresses and strains in elements of undercarriage steel constructions of heavy haulers and state the law of mathematical expectation of stress amplitude. The polynomial relation is set between specific energy input and mathematical expectation of stress amplitude. The maximum permissible operation conditions are found for heavy haulers based on criteria of energy intensity of blasted rock transportation and endurance of steel constructions of rear axle.

The article describes mathematical model of positive-displacement hydropercussion system of single-sided back action. The principal dynamic similarity criteria found are: the reduced ratio between areas of back-stroke chamber and gas chamber; the value proportional to the ratio between potential energy of accumulator and kinetic energy of hammer; the dimensionless lengths of back stroke and gas strut. Based on numerical calculations performed within a wide range of input parameters (similarity criteria), the author has plotted nomograms of isolines of the integral input characteristics and oscillograms of dynamic characteristics, which enables revealing basic mechanisms of behavior of the discussed system in the single-blow limit cycles. In the domain of practical significance parameters, the analytically estimated dimensionless pre-blow velocity should not be higher than 810 units.

The authors propose a calculation procedure for electromagnetic processes running in converters with clamp diodes based on the numerical simulation and method of switching functions. The procedure is specific for the capacity to calculate basic indices of energy efficiency of semiconductor converters in various work modes. Moreover, the procedure is universal in terms of number of voltage levels and number of phases. Owing to modern computation techniques, the time and labor inputs in calculation is greatly reduced. The proposed procedure has been experimentally tested.

The authors discuss experimental physical simulation of operation of loading aggregates with loading stars. The main influencing factors and their ranges are determined, and the obtained results are interpreted. The authors give basic relations characterizing output and capacity of a loading aggregate with lading stars.

It is suggested to enhance output of marketable dimensional stone in quarries with complex inclined and flat-lying fracture networks by minimizing in-process loss as well as by optimizing cutting bench height in order to benefit from higher production rate and lower cutting cost. The procedure has been developed for calculating rational parameters of a combination method of high-strength dimensional stone preparation for cutting at the deposits with complicated ground conditions based on the high-bench two-stage scheme when the first stage is wire sawing of solid blocks and the second stage is cutting of solid block into marketable size blocks using dimensional stone drilling rigs.

The article describes evaluation of natural draft (thermal drop of ventilation pressure) and determination of its direction in a mine. The measurements taken on main mine fan are processed based on the methods of mathematical statistics. The results allow evaluating the natural mine draft at the preset confidence coefficient, and the offered algorithm enables on-line control of mine ventilation.

The article describes studies into morphology of gold in the initial ore and mining-generated silt in the weathered crust of the Yenisei Range using the methods of optical and electron microscopy. The authors have determined sizes and shapes of gold grains, nature of intergrowth of gold, ore and rock-forming minerals, and microadmixtures characteristic to free gold particles discovered in the initial ore and in old tailings pond.

Based on the mineralogical research package, the authors state adequacy of compositions of modified kimberlites and mineral processing slurry. Investigation results show high content of clayey minerals such as talcum, talcum-saponite, chlorite-saponite, Na-saponite and X-ray amorphous phase up to 50 %. Calcite, dolomite and serpentine are present. Using optical microscopy, infrared spectroscopy and X-ray microspectral analysis, the surface composition of natural diamonds is studied when they interact with the traced minerals. The authors have found the sequence and conditions for mineral formations on diamond surface during processing of metasomatically modified kimberlites.

In focus are issues of metallurgical slag disintegration by centrifugal-impact crushers. The article shows the model of breaking a piece of material in the centrifugal-impact crusher chamber. The scheme of force interaction between slag particles and crusher chamber is developed considering spread inertia load. It is found how structural parameters of crushing machines are connected with the process properties of slag, and the velocity and physico-mechanical properties of a piece of slag are related. The authors give technological recommendations on adapting centrifugal-impact crushing to mining waste pretreatment flowcharts.

The analysis of floatability of scheelite with FX-6 agent (produced in People’s Republic of China) shows that, as against sodium oleate, FX-6 consumption is to be increased in the bulk flotation circuit by 25 % in order to have a comparable output. Given more stringent conditions in terms of depressor for retreating of rougher concentrates, the increased consumption of FX-6 enables obtaining the final concentrate with 60.4 % recovery of WO ₃ where the increment by 0.63 % is thanks to essential reduction in sheelite loss in slurry. Based on the laboratory testing results, FX-6 agent is recommended for commercial trial.

The numerical exercise of two subprocesses-attachment and detachment of air bubble and mineral particle-illustrates feasibility of 2-3 times improvement of concentrate quality in separate flotation of sand and fine material as compared to the standard processing. This effect is achieved owing to optimization of ratio of bubble diameter and dissipation energy for each out of 36 fractions of particles differing in size and content of copper. The relationship of hydrodynamic factors depends on the size of the particles and on the distribution of metal in them.

The lab tests have been carried out to examine the influence of different factors on selectivity of chalcopyrite flotation from copper sulfides with moderate content of pyrite. The authors use the factorial design of the experiments. It is studied how the grinding fineness and xanthate concentration influence flotation of chalcopyrite and pyrite at different lime-adjusted pH values of the pulp. It is found that the highest influence on copper recovery is exerted by the size of the ground ore, pH value and collector consumption. In view of the high activity of pyrite and the intergrowth of chalcopyrite and pyrite with barren rock, it is required to grind ore up to 75-80 % content of size -74 µm, while pH of the pulp is to be maintained at the level of 11 in all flotation circuits.

Based on the analysis of etymological hierarchy of subsystems inside a complicated system, the authors substantiate and put forward definition of a subsoil development method structured based on the degree of complexity of the development. It is hypothesized on information analogy between patterns of substance flows in biological and geotechnological systems, and the procedure has been offered for quantification of integrated subsoil development in terms of correlating the substance of lithosphere that enters a technological level and that passes to the next one, based on homeostatic transformation of mechanisms of biological substance flow where informative elements are replaced for technological target analogues.

In accordance to the agreed terminology, it is concluded that mineral mining and processing industry cannot be environmentally clean. For these industry branches, it is assumed sufficient to transfer to ecologically justified technology and production featuring minimized environmental impact. The article offers formulation of basic conditions and innovation principles for integrated development of mineral mining and processing. In terms of Transbaikalia, the author introduces the notion of “regional power engineering” ensuring faster growth of individual mining regions and handling of their social and economic issues.