Vol 53, No 2 (2017)

For theoretical description of interaction between geomechanical and physicochemical processes in multiphase coal seams, the author for the first time proves the existence of an analytical “extension” of the operator connecting Langmuir’s equation and the kinematic expression for pendulum waves in highstress geomedia of hierarchical block structure.

A new approach to local rockburst hazard problems and rockburst prediction is demonstrated in terms of acoustic measurements in two mine workings of Joint Kirov Mine, Apatit Co. The new approach is based on spectrum–correlation analysis of acoustic emission signals, on the one hand, and on the Griffith−Irwin fracture model, on the other hand. Acoustic emission signals are recorded using Prognoz-L new-generation portable system for local rockburst hazard monitoring. Prognoz-L provides digital recording and processing of a wide range of acoustic signal parameters. The analysis of spectrum parameters of the recorded signals confirms applicability of the innovative software/hardware system to predict dynamic events in rock masses.

One of the issues considered in the design and dynamic resistance of structures (as seismic or explosive) is the use of materials which cause reduction in the force applied on the structure. With regard to the fact that greater loading is on the wall of concrete structures, the use of materials that reduce explosive force on the structure wall are among explosive force reduction methods.One of the viscose and damping materials of polymers is FRP, and in this study the FLAC3D software is used to evaluate the effect of this material on reducing force implemented on the walls and hence reduction of wall movement due to explosion. The concrete wall along with the FRP layer is modeled under dynamic loading. The effect of damping coefficient, number of FRP layers and concrete wall thickness has been evaluated.

Formulas and schemes are presented to determine lengths of charges and their inert gaps. The calculations are based on the theory of superposition of seismic blasting waves in a rock mass. The proposed procedure enables calculating parameters of distributed charges under any ground and geotechnical blasting conditions ensuring high-grade fragmentation, elimination of flyrock and reduction in drilling operations.

The researchers analyze energy processes running in an autonomous electric power system consisting of a synchronous permanent magnet generator and a semiconductor converter. Current, voltage and capacity of key components of the system are evaluated, and the system operation modes are determined for the variable magnitude and character of applied load at the constant voltage output frequency. Parametrical law is proposed to control semiconductor frequency converter serially connected to load and generating reactive power. The influence of the converter on the basic design parameters, energy specifications of the synchronous generator and the system as a whole are evaluated.

New results that solve the important scientific task of providing electrical networks with an isolated neutral voltage up to 1000 V in mining enterprises are obtained. The method for measuring the admittance of insulation networks with isolated neutral voltages up to 1000 V, which will provide improved accuracy and speed measurement admittance network insulation, is described. The measurement is made by adjusting the additional conductance to ensure equal quantities of module phase voltage to earth and zero phase-sequence voltage. In this connection the additional conductance corresponds to the admittance of network. The simulation model of a method of measuring the admittance of insulation using the Matlab/Simulink environment is analyzed. The proposed method is simple, as the instrumentation, singlephase voltage transformers that are needed to measure the admittance of network, are in the service manual of the energy management companies.

The author analyzes the method to prevent gas-dynamic events during mechanized mining of carnallite at Upper Kama potassium–magnesium salt deposit. The method ensures efficient gas drainage and relaxation of outburst-hazardous rocks due to a horizontal drainage borehole slotter in the sidewall of a face entry. The data of the mine experimental studies are presented. The time behavior of residual gas content and air sorption indexes of carnallite in the influence zone of the degassing slot is determined. It has been found expedient to use destressing slotting to prevent gas-dynamic events during mechanized mining of carnallite.

The author proposes a promising technology to separate monolith stones and preformed blocks for construction from rocks mass using a diamond rope cutting machine ensuring reduction in labor content, cost and loss as well as enhancing the process production output. The analytical model is developed, and the dependences between the material loss and the technology parameters are found. The main standards are formulated for the technology, and the ways of improving the diamond rope cutting machines design based on material loss minimization are specified.

It has been found that the rated and actual data on methane emission in production headings in some Kuzbass mines disagree. The air and gas control shows that actual methane emission from broken coal is much less than the rated data when a coal shearer has high advance velocity and production output. The authors demonstrate the connection between an average diameter of broken coal fragment, shearer advance velocity and drum rotation speed using Darcy’s law of flow and Langmuir’s adsorption equation. It is found that methane emission from broken coal and natural coalbed methane content relate nonlinearly and that the relationship of absolute methane emission, shear advance velocity and production output has an extremum.

The article gives new experimental data on chemistry, phase composition, structure and physicochemical properties of surface of minerals composing metasomatically altered kimberlite rocks. The authors have determined formation conditions and basic genetic types of mineral micro- and nano-size phases on diamond surface in the form of aluminosilicate minerals, thin coats of clayey minerals, calcite and dolomite bound with carbonate cement, as well as their negative effect on recovery of diamonds by foam separation. The mechanisms and efficient methods of combined energy effects on the natural heterogeneous system of diamond and surface mineral phase are found to rupture hydrophilic mineral films on diamond surface, prevent their repeated formation and reduce diamond loss in processing of diamond-bearing kimberlites.

The experimental test data on magnetic properties of the waste iron-containing mineral materials under radiation-thermal treatment are presented. It is found that the volume magnetic susceptibility of pyrite- and arsenopyrite-containing wastes has increased 5 times on the average. The authors demonstrate that radiation-thermal magnetization and magnetic separation allows production of KOS-3 grade tin concentrate meeting fuming process requirements from wastes of Novosibirsk Tin Works.

The authors present the data on the substance analysis of gold–copper–arsenic flotation concentrate. Gold and copper recovery by autoclave leaching of the concentrate has been studied. It is found that maximum gold and copper recovery under optimum conditions reaches 96 and 92%, respectively. The profitability of the proposed process flowsheet is proved by the technical-and-economic calculations.

The wind-induced dispersion of waste materials from mining operations results in the dust accumulation around mines, which in turn lead to negative environmental and economical impacts. In addition, the oxidation of sulphidic minerals extracted from mines promotes the creation of sulphuric acid which subsequently promotes the release of a whole range of metals. As a result, Acid Mine Drainage (AMD) contains high concentrations of acid and dissolved metals. When this toxic mixture flows into groundwater, streams and rivers, it gives rise to several environmental problems. Here, in this paper, we investigate the stability and permeability of the sulfide soil in the Angouran mine, the largest lead and zinc mine in the Middle East, by employing a biological process, biogrouting. Angouran mine is subject to a considerable amount of AMD production due to the water penetration in the soil, which is largely deposited by the dust produced from the mine and storage factories. Biogrouting method exploits bacterial hydrolysis to form calcium carbonate. Consequently, calcium carbonate sediments in the form of cement and consolidates the soil. Our findings show that the soil is stabilized through the inhibition of dust dispersion by biogrouting. The biogrout prevents the protrusion of water inside depots and decelerates the formation and protrusion of acidic drainage and latex consisting of heavy metals into the ground.

The application of integrated monitoring of ground subsidence, including geotechnical calculations of rock mass movements, leveling and satellite radar interferometry, is considered in terms of the Karaganda Coal Basin. The satellite radar interferometry data show reliable measurement of ground subsidence as a consequence of underground mining.

The authors propose the approach to validation of the surveying control accuracy in safety monitoring of earth dams in terms of liquid waste receivers at mines. Based on the system structuring of types of earth dams and their elements, estimation of influence of loads and effects exerted to these structures, as well as the analysis of accident risks using the Hazard and Serviceability Analysis, an ideal sign model of earth dam safety monitoring has been constructed and the scope of field observation has been specified to record hazardous off-sets and prevent hydrodynamic accidents. By modeling an ideal earth dam, the authors determine the dam stress–strain state criteria. From the condition of non-admittance of limit equilibrium disturbance of the earth structure, the requirements on the accuracy of horizontal and vertical surveying control over structural elements of dams are set.

The procedure of revealing water-saturated areas near underground openings by the data of radars with resistive-loaded antennas is developed. The key identifying parameter (attribute) of the procedure is the information entropy showing specific character of function of distribution of radar trace amplitudes. It becomes possible to distinguish anomalies in the profiles using the attribute after amplitude equalization. The procedure of processing of traces is described and exemplified, and the reasons of the entropy parameter efficiency are explained. For the comparison, the author considers alternative identifying parameters that appear less efficient as against the entropy attribute either for their weak capability to reveal anomalous sections in profiles or for the low interference immunity.