Home – Home – Jornals – Thermophysics and Aeromechanics 2024 number 4

The paper presents the results of an experimental study on coolant flow patterns at the inlet section of a fuel assembly (FA) in the cartridge core of a reactor for an RITM small nuclear power plant. The objective was a study on influence of different inlet elements on the coolant axial velocity distribution. This task was performed by a series of experiments on a scale-up experimental model covering the inlet section components from the calibration washer up to the attachment unit between fuel rods and the diffuser. The model also covers the section of the fuel-element bundle between the absorbing grid and the spacer grid. This study is based on the pneumometric method for several critical cross-sections over the model length. The allocation of measuring points covers the entire cross-section of the model. The coolant flow features are visualized using digital maps for the working medium flow axial velocity in the fuel rod bundle cross-section. The experimental modeling can be useful for optimizing the hydraulic profiling of the components at the inlet of the fuel rod assembly. The set of test data can be applied for validation of the LOGOS CFD software and for adjusting the technique of heat and fluid computations for the core zones under a cell approximation.

Models of the severe-accident SAFR module used to calculate the cladding melt relocation along the fuel pin surface during its melting are presented in relation to severe accidents in fast-neutron reactors cooled by liquid metal. The choice of the basic system of equations and closing relations is presented. The models are validated based on experiments on melting and flow of cladding simulator melts. The error of calculating the cladding mass loss due to its melting and flowing along the fuel pin surface is estimated.

A density and a volumetric thermal expansion coefficient of the LiK₃Pb₄ ternary alloy (12.5 at. % Li; 37.5 at. % K; 50.0 at. % Pb) in the liquid state are measured for the first time. Thermal properties are studied using a gamma-ray attenuation technique in the range from the liquidus temperature T_L = 812 K to 990 K. The LiK₃Pb₄ solid alloy is known to be an intermetallic compound. Its thermal analysis at cooling from the liquid state carried out in this work has shown that the compound is likely formed by a peritectic reaction at 789 K. Based on the experimental results obtained, a table of recommended values for the volumetric properties of the LiK₃Pb₄ melt has been developed in the studied temperature range.

The study presents the results of numerical simulation for a process of generating the ash liquid phase zone in the aircraft engine combustion chamber. The simulation was performed for three operation modes: the aircraft enters an ash cloud while cruise flight, the aircraft exits the ash cloud during climb-out; the aircraft exits the cloud during the flight idle mode (recommended by ICAO). This study was conducted for the case of a dual-flow turbojet engine PD-14 (the mainline aircraft MS -21) under the impact from the Sheveluch volcanic ash in the air. Our simulations revealed that there are significant zones inside the PD-14 engine combustion chamber where the gas temperatures are above the meting point for volcanic ash. The high temperatures zones (creating a risk of volcanic ash melting inside the engine) account for over 54 % of the flame tube volume. Additionally, for the nominal flight mode (climb-out), the volume of ash melt zone exceeds 81 % of the total volume, and the flight idle mode provides only 25.3 % of the volume.

In the regimes of mixed convection, the Czochralski method investigates numerically the effect of a melt layer height on hydrodynamics and convective heat transfer in the range of relative heights of the heptadecane layer 0.1 ≤ H/R_С ≤ 2.0 with a step of 0.1. Calculations were performed using the finite difference method at a fixed rate of crystal rotation corresponding to the Reynolds number Re = 95, with the Grashof, Marangoni and Prandtl numbers Gr = 1215, Ma = 2930, Pr = 40.35 for the ratio of crucible radius to crystal radius R_С/R_S = 1.94. In this range of parameters, the flow has a laminar, steady and axisymmetric character. The evolution of the spatial flow shape, velocity and temperature fields, radial distributions of local heat fluxes, and integral heat transfer is studied depending on the relative heights of the heptadecane layer.

A new model of the phase equilibrium line (PEL) of methane has been developed on the basis of the Clapeyron-Clasius equation and the relations of the renormalization group (RG) theory. In contrast to the known PEL, when describing the density of a saturated liquid ρ⁺, density ρ^- and pressure ρ_s, of saturated methane vapor, a system of mutually consistent equations (CE) including those describing the saturation density line and saturation vapor line is used. These equations have a number of common parameters: critical indices, critical pressure, critical temperature T_c, critical density, as well as a series of coefficients of the average diameter model, d_f coefficient D_2β, complexes D_2β/D _1-α and D_2β/D_τ, calculated within the framework of modern RG theory for asymmetric systems. Based on the proposed approach, a methane saturation line has been developed; its average diameter in a wide vicinity of the critical point is described in accordance with the RG theory by the dependence d_ƒ=D_2βτ^2β+D_{1_α}τ^1_α+D_ττ, where τ = (1 - T/T_c). It has been established that d_ƒ = d_ƒ(T) within the framework of the proposed approach is a strictly decreasing function of temperature in the range from the triple point to the critical point. It has also been found that the derivative of the vaporization heat with respect to temperature, in accordance with the principles of thermodynamics, has a minimum in the vicinity of the triple point. Within the framework of the proposed PEL model, experimental data on ρ⁺, ρ^-, and ρ_s published by R. Kleinrahm and W. Wagner in 1986 are provided with standard deviation 0.0011 %, 0.0072 % and 0.0012 %, respectively, that is, with greater accuracy than the international equations of U. Setzmann and W. Wagner derived in 1991.

The dynamics of droplet interaction with a biphilic surface based on the lattice Boltzmann method with multiple relaxation times (MRT-LBM) is numerically simulated. The biphilic surface is a superhydrophilic circle located on a superhydrophobic plane. The paper describes various aspects of droplet spreading after its impact onto the superhydrophilic spot surface, rebound, and formation of a residual droplet for several sizes of the superhydrophilic region. Three typical regimes of droplet interaction with the biphilic surface are identified: droplet separation from the surface, transitional regime, and adhesion. Moreover, the velocity fields inside the droplet during the entire process of interaction are analyzed.

This paper presents the results of development and experiments with a looped thermosyphon with a microstructured heat transfer surface (3D printed) for the case of a flat evaporator and ethanol coolant. The thermal parameters of this device were tested for the temperature in the range from 20 to 128 °С and for the heat flux ranging from 25 to 530 W and for device filling level of 40 ml (100 % of the evaporator volume). It was found that the heat exchanger with pillar-array surface provides the total thermal resistance about 0.18 K/W (corresponding to the top input heat flux equal to 530 W). The developed micropillar array structure for the inner surface of heat exchanger improves the loop thermosyphon efficiency.

To investigate the slip mechanism of the slope with weak interlayer, the location of the weak interlayer within the slope was determined by on-site monitoring using the Hequ open pit mine as the engineering background, and a three-dimensional numerical model was established based on this, and the study of the potential slip surface and key units of the slope containing weak interlayer was carried out. The potential slip surface inside the slope with weak interlayers is determined from the perspective of displacement contour and maximum shear strain increment. The principle and method of key unit identification for the slope with weak interlayer is proposed. The initial key unit on the potential slip surface of the slope with weak interlayers is identified, and the dynamic breaking path of the key unit on the potential slip surface of the slope with weak interlayers is determined.

The difference in energy accumulation in coal and rock under the same stress level is analyzed, and it is found that the difference of energy accumulation of coal rock under the same stress level mainly depends on the elastic modulus of coal rock material. Based on the structural characteristics and mechanical properties of coal-rock, the mechanical model of combined coal-rock body was constructed and analyzed, and the calculation formula of partition energy storage of combined coal-rock body was deduced. The axial compression test of combined coal-rock body under different loading rates was designed and carried out. Finally, the differential energy instability model of the combined coal-rock body was constructed. An evaluation index of the impact tendency of the combined coal-rock body considering the elastic energy difference and the release time is proposed, which provides a multi-scale criterion for accurately evaluating the impact propensity of the combined body.

The authors design and estimate a room-and-pillar method for mining inclined orebodies with combination of two approaches to ground control: through natural stability of rock mass and by means of overlying rock caving. It is shown that in rock mass under tectonic stresses, it is safe to extract ore reserves from rooms and from temporal ore pillar under protection of rock overhang. Due to inclination of an ore body, rocks in the pillar and in the block bottom fail mostly by way of shearing. The efficient ratios of a minimal width of a temporal ore pillar to a span of a stope are determined.

Fundamental considerations like drillability and tool wear may be pondered for development of deep well drilling for oil and gas, and tunneling projects. Careful considerations of key parameters may enhance the advance rate, operational costs, activity completion timeline and inventory control for spares. NTNU/SINTEF developed drilling rate index (DRI), bit wear index (BWI) and cutter life index (CLI) to quantify drilling and TBM related parameters. Until now, most of the research work has been carried out to develop models in order to recognize the effects of rock properties on drillability. However, very little if no studies have been conducted on the prediction of bit wear using BWI. This work deals with the effects of different geo-mechanical parameters of rocks on the drillability and the bit wear. The work shows that both drillability and bit wear are affected by physical and strength parameters of rocks. Moreover, various statistical models (with R² ≥ 0.83) have been developed through simple linear regression analysis (SLRA) and multiple linear regression analysis (MLRA) for the prediction of NTNU/SINTEF indices (DRI and BWI).

The authors propose an approved integrated approach to assessing influence of coal-rock mass on coal faces by a gas-based criterion through the isotope analysis of coalbed methane. The quantitative ratios of carbon isotopes of methane are determined in coal samples and in mine air samples from seven operating mines in Kuzbass. The geometrical parameters of such zones are assessed, and the maximal methane volume capable to affect a coal face during its operation is found. It is emphasized that the gas volumes and the methane migration zone parameters differ greatly when found using a traditional method and the integrated approach with the carbon isotopic analysis of methane in mine air and in coal.

Gas emission during destruction of coal samples in a mill is measured experimentally. Using the Skochinsky Institute’s procedure, emmitable gas amount is calculated as function of coal particles. Coal samples for the tests were taken in an outburst-hazardous seam. It is found that the decrease in the size of coal particles to 0.1 mm increases gas emission by several times. The authors developed a model of force interaction between methane molecules in micro-porous coal structure and surface of coal macro-molecule, and a calculation procedure for gas emission in coal as function of its degree of breakdown.

The authors developed a resource-saving and energy-efficient technology for integrated processing of eudialyte concentrate. It is found that the main losses of valuable components (Zr and REE) are associated with leaching cake. The effective methods and modes of processing of pregnant solution are determined to ensure high recovery of Zr and REE owing to conversion of silica gel and thanks to successive extraction of zirconium phosphate and rare earth carbonates from pregnant solution. The proposed complimentary methods of regeneration of reagents and shutting off of water circuits ensure recovery of zirconium and rare earths from eudialyte concentrate. The developed technology provides additional marketable products (sodium metasilicate and ammonium nitrate), as well as economic expediency and improved ecological safety of eudialyte concentrate processing due to regeneration of calcium carbonate.

The research focuses on the specificity of flotation of carbonate-fluorite ore waste at Yaroslavskaya Mining Company. The waste composition and process properties are examined. Fluorite in the test waste occurs in mineral concretions and in slime. The problems in flotation of old mining and processing waste are governed by specific surface properties of particles, film coatings and structural transformations. The promising methods to induce conversion of components in flotation pulp are discussed. It is found that ultrasonic and electrochemical treatment of waste components promote selectivity of their separation. The indicators of processes at fixed time intervals and under special effects are analyzed. Flotation with ultrasonic and electrochemical pre-treatment of pulp substantially increases fluorite concentration in froth and enhances selectivity of fluorite separation from calcite. Recovery of fluorite in concentrates with CaF₂ content more than 94% rises by 2.97-4.58%. It is demonstrated that it is possible to reduce mass fraction of silicon dioxide in concentrates by 0.3-0.5%.

The studies on vanadium production are generalized, and the promising nature of flotation is demonstrated in this regard. The prognostic selection of fulvic acid FulvAc as a selective collecting agent relative to vanadium occurred as vanadyl VO²⁺ in acidic pregnant solutions is justified. The analysis of chemical reactivity studied the mechanism of vanadyl extraction and concentration using chelating agent FulvAc. Computer modeling is performed for a flotation system representing a slightly soluble metal complex of vanadyl fulvat [VO²⁺ - FulvAc]_n . Efficiency of FulvAc is proved by lab-scale flotation tests with recovery of vanadyl not less than 92%. Vanadium oxisols are demandable by different industries, and [VO²⁺ - FulvAc]_n is usable as complex mineral supplements for fertilizing mixtures for urban greening.

The authors analyzed some reagent regimes in flotation of nepheline from loparite ore tailings: mixture of tall oils, hydroxamic acids in combination with distilled tall oil; mix of tall oils with addition of polyalkyl benzene sulfonic acids or amine-containing collectors. The nepheline concentrate produced in the optimized reagent regime contained Al₂O₃ 27.18-27.57%. With addition of tall oil polyalkyl benzene sulfonic acid, activity of the collecting mixture reduced, and the produced concentrate quality lowered to Al₂O₃ 26.33%. Two methods to bring flotation concentrates to a standard quality are discussed. The use of magnetic separation allowed production of nepheline concentrate with Al₂O₃ 28.0-28.3% at the recovery of 72-76% compared to the initial product. Direct cationic flotation with agent Flotigam-2835 in an acidic medium with рН 4.5, created by sodium silicofluoride, produced nepheline concentrate with Al₂O₃ 29.63% at the recovery of 65.9% compared to the initial product.

The authors theoretically substantiated and, using in-situ measurements, proved the method of determining kinetic characteristics for coal bed gas: content, diffusion factor, mass exchange and rate of desorption. These data are required for the development of technologies of coal mining and methane utilization. The method involves solution of an inverse problem within the framework of a nonlinear model of gas emission from a particle placed in an isolated container, using the data on time change in thermodynamic parameters (pressure and temperature) in a sealed canister with coal chippings. The model analysis shows that ratio of methane concentrations at different moments of time is independent of gas content. This enables development and numerical implementation of a two stage algorithm: first, by solving an inverse problem with time-dependent coefficients, the factors of diffusion, mass exchange and desorption are found; then, with minimization of a special function, the gas content is determined. The in-situ data are obtained using coal chippings from drilling in an operating mine in Kuzbass, by means of measurement of pressure and temperature in five canisters for 10 days. The interpretation of the data made it possible to assess the methane content in the test coalbed site as 4 kg/m³.

The field research of the geomechanical behavior of rock mass was carried out in the neighborhood of an abandoned railway tunnel by means of multi-channel analysis of seismic surface waves. For the interpretation of the results, the spectral dispersion images of waves along the tunnel were selected and analyzed. That made it possible to obtain the velocity patterns of waves in enclosing rock mass, and to identify the low-velocity zones in it. The results prove the applicability of the method of determining structure and condition of adjacent rock mass surrounding underground structures.

Open mining operations generate deep open pits, and the industrial infrastructure and buildings become closely spaced with the open mining zone as a result. The situation requires implementation of integrated monitoring and periodic assessment of pitwall stability considering up-to-date data on properties and condition of rock mass. This article describes an approach to monitoring and assessment of pitwall stability on a hazardous site. The periodic seismic profiling reveals great disruption of the test site. The stability assessment of the test site using the limit equilibrium method shows the slope instability. It is concluded that prediction of failure zones on the test site is advisable to carry out by integrating the field inspection and computational methods of slope stability control.

The static and dynamic wedge indentation resistance tests involved plexiglass and marble samples. The static tests recorded the indentation resistance force as function of penetration depth. The dynamic tests included a rope gravity drop hammer. The tests focused on the dynamics of penetration of a dropping massive wedge into a plexiglass sample. The indentation resistance was determined using an accelerometer mounted on the wedge. Plexiglass as a model material allowed finding the shape and size of the main cracks generated by wedge indentation. The test data on the wedge indentation resistance and on the main crack size were compared with the theoretical values. The comparison showed a good agreement of theory and static experiments with plexiglass samples. In the dynamic tests, the theoretical indentation resistance appeared to be less than the test values by 25% at the most, at a good agreement between the sizes of the main cracks.

The article describes the stability testing and calculation results for a heavy column set on the surface of a granular medium, and for a plate buried in the granular medium. The column and plate were exposed to a pre-limiting static load. The granular medium was subjected to multiple weak impacts. The lab-scale tests determined that under such loading, the granular medium evolved gradually to the critical condition and lost the shearing strength. The rate of approaching the critical condition grows with the number of impacts. The critical number of impacts before failure of the medium obeys the log-normal distribution. The most probable value of the critical impact number increases exponentially with the decrease in the static load. The DEM-based modeling of the stability loss in the plate buried in the granular medium yielded the results that qualitatively coincided with the test data.

It is investigated how the content of basalt fiber with a diameter of 23 µm influences specific energy intensity of failure in concrete D2000 and in light heat-reflecting concrete D1000. The mechanisms of alternating temperature effects on dynamic impact resistance of fiber-reinforced concrete are determined. After 12 cycles (freezing temperature - 50 ± 2 °С), the energy cost of failure in the samples of concrete D2000 at the fiber volume ratio of 2.7% totals 1962 J/m², which is 3.6 times higher than the energy intensity of failure in the samples of non-reinforced concrete. It is found that concrete with a porous absorbing aggregate made of expanded vermiculite possesses higher dynamic impact resistibility than high-density concrete. The energy intensity of failure was 5038 J/m² in vermiculite-containing heat-reflecting concrete and 2326 J/m² in fine-grain concrete D2000. The failure energy intensity in vermiculite-containing non-reinforced concrete after three freeze-thaw cycles drops by 71%, from 5038 to 1473 J/m². At the fiber volume ratio of 2.4%, the energy intensity of failure in fiber-reinforced concrete decreases by 9%, to 4608 J/m². These results can help increase the impact resistibility of shotcrete lining, including situations after the adverse effect of cyclic freeze-and-thaw.

The geodynamic research of coal-rock mass in mines in the Donbas uses composite seismic signals which appear on ground surface during coal mining. The search of regular patterns in geological response of rock mass to seismic waves is based on the main physical principles of elasticity: dependence of the signal energy on the proximity to the vibration source and dependence of P-wave velocity on the density of the medium. The authors of the article discuss the results of seismic monitoring in the mine fields in the Donets-Makeevka region of the Donbas. The energy and spectrum characteristics of seismic signals are correlated with the geodynamic processes and with the geological section parameters. The direct proportional dependence is found between the total thickness of jointed rock mass and an integrated parameter including azimuth of any component of seismic waves. The analysis of spectra of composite signals shows that their frequency characteristics allow differentiating areas of maximal softening and compaction in coal-rock mass and eventually enable delineating faulting influence zones which are the anomalous accumulations of methane.

Density, porosity, P-wave velocity and Leeb hardness were determined for travertine samples from different quarries in Turkey, and the relationship of these properties with uniaxial compressive strength values was evaluated. Exponential relationships were obtained between UCS and physical and mechanical properties of test samples. The strongest relationship was obtained between UCS and the Leeb hardness, at the correlation factor R² 0.91.

Inspection of underground openings in the Taimyrsky Mine, in the previously flooded areas, revealed increased jointing, rock falls in roofs and sidewalls, dome folding in roofs and fracturing of shotcrete lining. The main cause of failures is dissolving of loose material in cracks in gabbro-dolerite rock mass, with its leaching out later on. The complex mode of the Oktyabrsky deposit ore occurrence is revealed within the Taimyrsky Mine field. Mining is greatly complicated by faulting, heavy jointing, low stability of rock mass and dynamic events induced by rock pressure. Condition of mine openings was analyzed, and samples of rocks taken in the flooding zone were tested: in uniaxial compression, the strength, deformation modulus and lateral deformation coefficient were determined; in tension, the strength was determined; the failure curves (cohesion and internal friction angle) were plotted. Stability of rock mass enclosing the Oktyabrsky deposit, including jointing, was estimated. Videoimage endoscopy was carried out in exploration and destressing boreholes in order to detect stratification and fracturing in moist zones in rock mass. The ground penetrating radar inspection of adjacent rock mass was performed. It is found that mine water and mine air have the corroding influence on metal and concrete elements of mine support. The ways of improving the mine support technology in moist rock mass areas are proposed. The recommendations on safe roadheading are made.

The authors describe the methodological approach to formation of geotechnical systems of deep open pit mines with regard to transient processes. Parameters and figures of subsystems of a geotechnical system, and their elements have a great number of interconnections and undergo changes within the space of life of an open pit. Their formation is considered as a set of stable functioning periods and transient processes. The terminological paradigm of structure, components and parameters of the geotechnical system of an open pit mine is described in the context of the open pit mine transport. The concept of adaptation of the technology and equipment subsystems during transient processes is presented as a mechanism of optimal functioning of the geotechnical system. The provision of their dynamic equilibrium is illustrated. Optimization of transportation as the most expensive process in open pit mining is based on integration of computer modeling techniques: geometrical, process simulation and economic mathematical. The key features of pitwall stability estimates in substantiation of the geotechnical system parameters are discussed. The approach to optimization of rock mass preparation by blasting on the basis of real-time adjustment of physical and mechanical parameters of rocks and rock mass data is described.

The geomechanical evaluation of safety is carried out for structural components of a mining system integrating caving and backfilling in extraction of ore reserves under bottom and in pitwall rock mass. It is found that safe distance between drilling and haulage openings in neighbor stopes depends directly on the height of a mining zone. The need of sequential cutting of drilling and haulage openings in the course of extraction of ore reserves from stopes is proved. The advance of heading operations over actual stoping should be not more than one-two mine openings depending on the rock mass quality. Stoping operations should eliminate formation of any pillars across the width commensurable with the stope or smaller. It is shown that operations in undermined or overmined zones are unsafe. The parameters of structural components which ensure safety of mining are determined.

An oil reservoir is simulated by a model composed of two rectangular glass plates. The space between the plates is filled with glass chips of the similar chemical composition as the plates have. The model allows studying fluid flow in the spaced dipole array representing two wells located symmetrically relative to a certain center. The wells are simulated by holes drilled in the upper plate. The experimentation aimed to assess potential oil recovery enhancement in case of using GBK-F composition. The dependences of fluid flow rate on time in the pumping well, and on the water percentage in the overall fluid volume are obtained. The influence of the intermission in the fluid flow on the oil pattern in the reservoir after treatment with GBK-F composition is analyzed. The efficiency of the reagent is proved.

The analysis of rock flow patterns under the cross-effect of contiguous faces uses the 3D discrete element method to reproduce ore drawing processes in underground mining at the Khibiny apatite-nepheline deposit. The study of ore drawing modes revealed the mechanisms of loss formation, as well as the rational designs of structural components of a mining systems and ore draw planograms. The numerical modeling results were verified during in-situ experimental blasting and sublevel stoping in different geological and geotechnical conditions in mines of the Kola Division of APATIT. A conception of sublevel stoping modeling is developed, and the guidelines are proposed for rating ore losses and dilution in underground apatite-nepheline ore mining. The efficiency of the reagent is proved.

The authors identified the cause of loss of diamonds with nonstandard natural luminescence intensity in X-ray fluorescent separation. The technology of adjusting spectral and kinetic characteristics of diamonds is developed as treatment of diamond-bearing kimberlite material by luminophore-bearing reagents including mixture of FL-530-type luminophores and anthracene. For reaching improved stability of luminophore-bearing compositions and for the better attachment of luminophores on diamond surface, it is proposed to enhance their oil receptivity by treating with a hydrophobization agent (potassium butyl xanthate). It is suggested to ensure maximal selectivity of X-ray fluorescent separation through prevention of adhesion of luminophore-bearing composition to kimberlite grains by adding dispergators at concentrations of 1-1.5 g/l. It is shown that hydrophobization of luminophore FL-530 by potassium butyl xanthate and the use of dispergators ensure selective attachment of luminophore at the surface of diamonds with nonstandard natural luminescence, as well as their selective extraction to concentrate. The overall reduction in the loss of diamonds in X-ray fluorescent separation is proved

Composition of collectors is one of the promising avenues in stimulation of flotation efficiency. When using a mix of reagents, their synergetic effect shows up not only at the mineral-liquid interface but at the gas-liquid interface as well. This study aims at connecting the synergetic effect of a cationic / anionic combination collector in reduction of surface tension with synergism of the surfactants in flotation. The tests were carried out to determine surface activity of physisorption in case of combination of these reagents. The results are comparted with the flotation activity and interaction parameter of the components of the combination. The findings can be a framework for the design approach to selecting combinations of collectors for flotation.

It is found that synergism of combination of anionic and nonionic surfactants in reduction of surface tension is connected with their synergetic effect in flotation. These effects have the same nature. The proposed hypothesis of synergism in flotation is based on the mechanism of physisorption of a collector in particle-bubble attachment. The conformity of mole concentrations of surfactants and maximal extraction of useful component to concentrate is experimentally proved. The causes of possible lack of the synergetic effect generated by cationic and anionic collectors in flotation when this effect is observed in reduction of surface tension are discussed. It is found to be necessary to take into account the interaction energy of a collector, mineral and an ambient. The analysis of change in wettability of minerals due to reagents can involve an approach using the Lifshitz theory of Van der Waals force and the acid-base interaction of contact objects. The findings can be used to develop procedures for selecting collectors and efficient reagent modes for mineral flotation.

The authors investigate depression of talc in its monomineral flotation with polymeric anion active reagents: carboxy methyl starch and carboxy methyl cellulose (CMS and CMC, respectively), sulfonates, as well as compounds with polyvalent cations of metals. Sodium polystyrene sulfonate with molecular mass of 10⁶ kg/kmol is more effective in talc depression than sulfonates of smaller molecular mass, but gives way to CMS and CMC. Cations of Mg and Al at concentration of 2.5 mg/l increase efficiency of talc depression with sodium polystyrene sulfonate by 4%. The further rise in concentration of cations of metals weakens depression of talc. Addition of sodium polystyrene sulfonate up to concentration of 250 mg/l changes electrokinetic potential of talc from - 20 to - 32 mV. As compared with CMS and CMC, polymeric sulfonates have lesser adsorption affinity to talc. The authors propose two alternative mechanisms of interaction between polymeric sulfonates and basal surface of talc: without polyvalent cations of metals and with preliminary addition of these cations.

Test flotation of pyrite used potassium butyl xanthate and sodium butyl dithiophosphate as collectors. The study of the influence exerted by the nature of a sulfhydryl collector on the flotation ability of pyrite included pyrite samples -74+44 µm in size. The findings on froth flotation of pyrite with addition of one or two traditional sulfhydryl collectors which display similar collecting action in treatment of pyrite at pH 8 are described. From the analysis of the kinetic curves of pyrite flotation, a new approach to the assessment of flotation activity of thiol collectors is proposed.

Preliminary ultrasound treatment of reagents meant for the flotation of slimes is studied. The study of the influence exerted by the ultrasound treatment applied to water solutions of nonionic collectors for flotation desliming of sylvinite ore focused on the change in characteristics of the generated foams: foam volume and height, foam ratio, moisture content, stability and breakdown rate. It is found that foamability of the solutions, foam ratio and “dryness” increase with the increasing sound power, whereas foam stability drops. The possibility of enhancing foamability and reducing stability of three-phase foams is assessed.

Electric disintegration of spodumene pegmatites is investigated. It is found that treatment with electric pulses ensures partial dissociation of monomineral spodumene, and the best extraction of spodumene crystals, either with or without concretions, takes place when initial rock is ground to a size of 1 to 4 mm. The crystals of spodumene remain unbroken, as in mechanical treatment, and represent whole pieces. The gravity separation later on allows production of spodumene concentrate for the subsequent lithium extraction.

The article presents the method of location of heavily fractured zones in rock mass. The method uses a geophysical model of electromagnetic radiation which accompanies discontinuity of rock mass. It is shown that for the location of a rock mass area with the change in the stress-strain behavior in the neighborhood of mine openings using the electromagnetic radiation method, it is required to assess the power of a source of rock failure by means of recording signals from sensors of electromagnetic radiation. An approach to building a software architecture to predict dynamic events induced by rock pressure is proposed.

The article discusses in-situ seismic tests carried out during operation in the mines Kazakhstan, Abay and Kuzembaev in the Karaganda Coal Basin for studying and predicting geological faults in coal seams. Seismic testing used the methods of reflection survey, transmitted waves, seismic location, as well as their combinations. The practical results of the in-situ seismic testing in complex geological conditions proved the efficiency of the listed methods, and enabled adjustment of the presence, position and stretch of expectable faults, revealed the absence of unpredictable faults, and detected the zones of change in hypsometry of coal seams, as well as other anomalies.