Home – Home – Jornals – Journal of Mining Sciences 2016 number 2

The article focuses on efficient analysis and test methods to determine nano- and micro- physico-mechanical properties of rocks and crystals. A modification of the classical elastic problems of contact mechanics implemented using the mathematical apparatus of fractional integro-differentiation is proposed. The authors build new models and algorithms aimed to advance the studies into properties and states of geomaterials based on the atomic-force microscopy techniques, and describe testing of the new approaches in calculation of the elastic modulus for hydrocarbons with nano-additives.

The analytical review covers the key factors that influence permeability of a coalbed under mining-induced alteration of stress state. The authors put forward an analytical relation between coal permeability, stresses and adsorbed gas to define parameters of gas leakage zone parameters and laws of mass-transfer. The analytically derived relation is compared with the known model of coal structure and with the experimental results. The proposed model of coalbed permeability allows mechanism of leakage and localization of seepage zones in coal provided that the model parameters are properly selected or found experimentally.

The article offers in situ test methods for cohesion and internal friction angle in rocks and at joints. Technologies and instrumentation for shearing of rock wedges in an open pit mine and for laser scanning and digital imaging of local falls and breaks of inaccessible rock blocks in pitwalls have been developed and approved for constructing of a limit equilibrium equation and for calculation of strength properties of rocks and joints. Rock wedges for the tests are prepared using various design drill rigs, the rock wedges are sheared using a 40-t jack placed in a special metal housing with an electric hydraulic pump. Exploration of inaccessible local falls in pitwalls uses electronic tachometers and 3D mine scanner. The tests and approval of the described exploration techniques have been carried out in open pits in Kazakhstan and Kirgizia.

The scope of the article encompasses features of natural and induced seismicity and the change in frequency plots when natural seismicity becomes natural-and-induced seismicity in mining areas and when induced seismicity becomes natural-and-induced seismicity in mines. It is shown how induced seismicity is connected with the subsidence of overlying strata in mines-seismic process propagates together with the subsidence but seismic activity lowers in the time of maximum subsidence and intensifies when subsidence ceases or decelerates. The authors lay emphasis on estimates of seismic activity in mines and give details of an integrated index F procedure tested in mines and adjusted within the 10 year-long period of application.

The solution to a hydraulic fracture problem for the model of Khristianovich-Geertsma-de Klerk is obtained on the basis of the modified formulation of the problem, which, in contrast with the conventional approach, employs the particle velocity rather than the flux. This served to complement the system of ordinary differential equations, resulting after spatial discretization, with the speed equation. The complete system is solved by the Runge-Kutta method for arbitrary initial conditions.The decaying influence of the initial conditions on key characteristics of a fracture (opening and length) at the end of a treatment is established and numerically analyzed.

Based on the strength and crack resistance tests of dolerite and gabbro-diorite samples subjected to bending as a function of loading rate, it is shown that the kinetic constants of strength in Zhurkov model have the same values in the localized and nonlocalized failure modes. The tests on destruction of an organic glass sample with an edge crack yield the similar results.

The article gives the results of mathematical calculations of change in the parameters of electromagnetic signals in stratified and damaged dielectric solid model structures exposed to pulsed acoustic treatment. It is shown that the acousto-electric transformations in such structures result in transition of energy of acoustic pulses to energy of electromagnetic responses in double electric layers. The amplitude-frequency parameters of electromagnetic signals are directly connected with the characteristics of the determinate acoustic effects and with the charge state of the stratified and damaged structures.

It has been found that gold mine waste in the Amur River Area (Priamurye, Russian Far East) contain associated minerals of gold belonging in the group of useful components. In view of the complicated nature of the mine waste, it is decided on the appraisal and recovery of the associated useful components with the help of rational technologies.

The article describes the research results on evaluation of rational technological parameters for open pit mining of Oshkurkovskoe apatite deposit using Wirtigen Surface Miners. Basic relations between the surface miner capacity, ground conditions and technological factors are substantiated. The authors have constructed lag models and determined optimal design capacity of open pit mine.

The authors analyze feasibility of voltage stabilization for permanent magnet synchronous generators in independent variable-frequency power networks. The method of voltage stabilization is based on series connection of the generator and a semiconductor converter generating wattles power. Basic energy characteristics of the semiconductor converter and synchronous generator are analytically defined, frequency constraints of the proposed method are found, and rational frequency range and overall power of the system are determined.

Electrical insulation of open pit shovels has been tested. It is found that line-to-ground short circuit current in up to 1000 V network is lower than setting current of safety cut-out. The authors propose a method to improve efficiency of safety cut-out of mining shovels and drill rigs. The method is based on superimposing D/C current on three-phase network with fixed setting of cut-out operation, i.e. when a person touches live parts the electrics is cut-out owing to increase in capacitance of phase relative to ground.

The article gives new experimental data on spectral characteristics of photoluminescence of natural diamonds extracted from deep horizons of Mir and Internatsionalnaya Pipes, Republic of Sakha (Yakutia) depending on composition of basic and additional optically active structural defects in crystals and on temperature during spectrum recording, considering kinetics of luminescence. It is hypothesized on applicability of low-temperature effects to enhance efficiency of photoluminescence separation of diamond crystals.

From the analysis of information on flotation of quartz, barite, hematite and diamond spar using cationic reagents (amines), the authors show deficiency of thermodynamic approach to explain flotation results by one type of adsorption due to ion-electrostatic mechanism. The discussion offers hypothesis that says that at low pH collecting ability of a reagent is connected with hydrophobic attachment of reagent ions in adsorption layer. In alkaline range of pH, the collecting ability is conditioned by formation and precipitation of ion-molecular associates in the adsorption layer of a mineral. These types of adsorption attach particle surface which is preliminarily made hydrophobic by ion-electrostatic mechanism. These adsorption types are active at bubble-liquid interface and can go to this interface upon rupture of water film between a particle and a bubble. According to the suggested hypothesis, liquid tension in the film becomes nonuniform and a surface force arises and expels kinematic constraint for particle-bubble attachment. The analytical review of the collected test data on cationic reagents proves the suggested hypothesis. The causes of breakdown of correlation between surface pressure and collecting ability for initial conditions of flotation are explained.

Air bubble and pyrite grain attachment is studied. It is found that mineralization area on air bubble depends on pulp agitation time, potassium butyl xanthate concentration and pyrite grain size. The authors show the connection between mineralization area of air bubble and weight of mineral load. Using experimental data, it is calculated how many pyrite grains from a narrow size range attach air bubble during pulp agitation time, and the weight of these grains is estimated. Physical forces on mineral loading exerted by pyrite grains -_{0.1 + 0.071, - 0.071 + 0.044 and -0.044 + 0 mm in size on air bubble at different pulp agitation times, as well as the absolute and specific retention forces are calculated, too.}

The article gives analytical and experimental data on separation of sulfide minerals in bulk concentrates of complex ores. The separation methods for minerals having similar process properties are selected. It is found which factors influence mineral separation efficiency in concentrates of rebellious and complex ore processing. The authors present fresh data on activating effect exerted by cations of copper on floatability of sphalerite, galena, pyrite and pyrrhotine species, as well as on activating effect of copper minerals. It has been studied how species of pyrite and nonferrous metal sulfides influence oxidation, floatability and depression. The selected methods to separate complex ore concentrates provide for multi-stage flotation circuit, with recovery of rebellious species into rough concentrates and products and their separation in different cycles later on. A system mode has been developed and recommended for dosing selective collectors, depressors and modifiers to achieve the best flotation performance.

The article describes theoretical and experimental data on dearsenation of gold-containing scorodite ore in water vapor. It is shown that roasting of scorodite with pyrite in super-heated vapor enables complete removal of arsenic and sulfur in the form of sulfides of the original material and exposes noble metals.

The author performs the comparative analysis of the international standards on determination of elastic properties of rocks from uniaxial compression tests, with benefits and shortcomings of the standards presented. The measurement data on lateral and transverse strains obtained in rocks and model metal samples under compression using different type extensometers are reported. The scope of the analysis embraces applicability of extensometers to the determination of elasticity modulus and Poisson’s ratio in rocks under variation in temperature. Examples of estimating elastic properties in thawed and frozen rocks are given in terms of enclosing rocks at Botuobinskaya diamond pipe.

The designed automated system for pitwall deformation monitoring consists of an independent data recorder, strain sensors, AD converters, and front-end and back-end controls. Data are accumulated in server in on-line mode via cellular modem. The self-contained tools are supplied from accumulators recharged by solar batteries, which expands operational life of the system. The system has been trailed in an open pit mine at Nyurbinskaya kimberlite pipe in deformation monitoring of faults in the eastern pitwall and estimation of its geomechanical stability.

The authors prove relevance of digital space data to be used for regional and local operational quantitative estimation of nature in the area of mining and processing. The research findings are analyzed in terms of environmental appraisal for the area of an open pit mine at Gusevogorskoe deposit of titano-magnetite ore with vanadium admixture (Sverdlovsk Region, Russia).

The article gives new information on integrated assessment of the environmental impact of mining in the south of Russia’s Far East. The assessment is based on: Earth remote sensing data; normalized difference vegetation index for nature-technology systems; combination of the calculated vegetation index and digital relief model to implement individual estimation of the induced impact and natural effects; joint analysis of the induced impact based on satellite monitoring and field survey data; computation of ecological-and-economic damage.