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Description of formation of a manmade backfill made of frozen briquettes using the cryoresource of the permafrost zone involves the phase transfer theory. The seasonal dynamics of the regional temperature is included in the closed life cycle of a solid substance as the main component of the geotechnology. A Stefan problem is adapted to heat processes in formation of a manmade frozen rockmass in the permafrost by filling a mined-out void with briquettes frozen on ground surface, with further injection of processing slurries having a positive temperature in remaining cavities. The numerical implementation program is developed for the set problem in 3D formulation. The freezing time of the artificial rockmass made of the frozen briquettes is related with the size of the briquettes, and with the temperature of the permafrost and the slurries. The frozen backfill in underground mined-out voids is a favorable decision in terms of ecology in mineral mining in the permafrost zone.

The authors implement a new model of calculating temperature field and stresses in frozen rock mass at all successive stages of sinking: rock freezing, shafting, concrete lining and thawing. The model allows assessing dynamics of temperatures and stresses in rock mass, in frozen wall and in concrete lining at the freeze and thaw stages with regard to the thermophysical and mechanical properties of the materials. It is found that functioning of the freezing pipes in the same mode in depth is nonoptimal and leads to excessive energy consumption.

In this study, combustion properties such as thermogravimetric analysis and differential thermogravimetric analysis, combustion profile, ignition temperature and peak temperature were analyzed for 3 lignite samples obtained from different regions of Konya in Turkey. In the kinetic analysis, activation energies were calculated separately for four different reaction sequences using the Coats-Redfern method. As a result, when the calculated activation energies, thermal and kinetic properties of the coal samples are evaluated together, it is seen that Beyşehir coal is more prone to combustion than other coals.

The article describes the studies into the current flow charts available for processing diamond-bearing kimberlites of complex material constitution. The theoretical and experimental substantiation is given for the methods to modify properties of the mineral components to enhance selectivity of their separation. Efficiency of luminophore-containing compositions is proved for weakly and abnormally luminescent diamond. Luminophores modify the spectral and kinetic properties of diamond crystals to the values at which diamonds become recordable and recoverable in the current flow charts of X-ray luminescence separation. Efficiency of integration of ultrasonic, thermal and electrochemical methods in removal of hydrophilic impurities from diamond surface toward enhanced recovery of diamonds by grease technology and froth separation is demonstrated. The method is developed to increase the corrosion resistance of ferrosilicon by means of its nitride coating which unsupports interaction with corrosive components of the water environment. Experiments justify that magnetic separation improves the quality of preconcentrates of float-and-sink separation owing to removal of up to 95.8% of magnetic minerals from the diamond-bearing material.

The characteristics of mineral floatability, namely, the wetting angle and the induction time, are examined. The agreement between the predicted floatability using these characteristics and the theoretical and experimental data is accessed. It is found that hydrophobicity defined by the wetting angle is not always a quantitative characteristic of floatation. The floatability predicted using the time of induction and mechanism of physisorption of collecting agents agrees with the tests and actual practice. The successive change in floatability of sulfhydryl and oxyhydryl collectors in transition between different reagents disagrees with the estimate of the collector force determined from the binding energy between the functional group of a collector and the cation of mineral surface. The force estimated as the effect of a physisorbed collector on the water interlayer between bubble and particle adequately describes floatability of minerals. The mechanism of physisorption of a collector is universal relative to different reagents, is applicable to the description of particle-bubble interaction and enables selecting the structure and composition of radical on an effective collecting agent.

The article describes the method of potentiometry in determination of characteristic diameters of air bubbles. The authors discuss feasibility of the Sauer diameter measurement of air bubbles using the difference of electrode potentials at different depths in flotation machine and with further evaluation of aeration intensity. The studies involved a two-phase system at different consumptions of air and frother. The highest aeration intensity is found from the checking tests of a three-phase system. It is found that the rate of increase in the difference between the electrode potentials linearly correlates with the Sauter diameter of air bubbles.

The article discusses hydrochemical modification of properties of zeolite-bearing rocks in East Transbaikalia. It is found that acid-based modification enhances adsorbability of natural zeolites. The technology of processing with chemical modification is developed for zeolite-bearing rocks with regard to the earlier research findings on mineral treatment by ultrasound, accelerated electrons and high-power magnetic impulses. The rate of dealumination and the silicon module of natural zeolites from East Transbaikalia are correlated with the sulfuric acid concentration. The implemented computer-aided modeling of zeolite minerals is based on the quantum-chemical interaction of particles. The authors depict the range of use of the high-quality zeolite products in the technologies of mining waste management.

In this study, the thermal decomposition of zircon magnetic tailing has been conducted to remove phosphate using a roasting process with Na₂CO₃ and water leaching. The research on zircon magnetic tailing processing, which contained monazite, xenotime, zircon, anatase, rutile and cerianite, aimed to test the effectiveness of roasting techniques for phosphate decomposition so that REE can be easily extracted. The optimal conditions to ensure phosphate recovery up to 93.27% were determined. In this condition, zircon and xenotime minerals are still confirmed in the roasting products using Na₂CO₃.

The authors have developed a procedure for estimating recovery dynamics of natural ecosystems damaged by mineral mining using the satellite observation data. The procedure uses the vegetation index of phytocenosis and the temperature of underlying terrain. The case-study of apatite-bearing ore processing waste revealed the time series of the vegetation index and the underlying terrain temperature of the incipient phytocenosis as compared with the phytocenosis of the surrounding natural landscape. It is found that the recovery of the natural ecosystems by generation of a biologically active medium activate the test factors to reach the values of phytocenosis of the surrounding natural landscape. The justification is provided for usability of the retrospective earth remote sensing data on ground surface in the objective estimation of recovery dynamics of natural ecosystems damaged by mineral mining in the Arctic conditions without undertaking land exploration.

The article presents a case study of dust emissions from the preparatory works for the opening of the mine "Cukaru Peki" near Bor, Republic of Serbia, including an analysis of the total deposited materials, which illustrates the practical application of the proposed methodology. The monitoring was conducted one year before the start and from January to September 2018 during the preparatory mining works. The analysis of existing data predicts the creation of deposited substances from the atmosphere. This paper evaluates the validity of the Gaussian model for predicting the potential impact of dust deposits generated during preparatory mining works.