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The article studies a mining system with stoping under open pit bodies at steeply dipping ore bodies of small and medium thickness using rubble concrete and dirt fill as ground control. The technology assumes upward mining on the levels at the total downward sequence of stoping. The limit variant of stoping in various geomechanical conditions is studied for a geotechnical situation of mining on three levels including two mined-out levels. The mining system parameters are substantiated using 3D FWEM-based mathematical stress-strain modeling. The dependence is revealed between the geotechnology parameters and the stress behavior, and between the stability of rocks in the structural components of mining and in adjacent rock mass. The areas of possible rock fracture are identified. The safety of the mining system is governed by the integrity of rubble concrete pillars and by the stability of the crown pillar.

The authors present the results of development of a powered roof support control system included in the machine group of top coal caving to a longwall conveyor. The methods of measurement of the conveyor loading by a swinging feeder, recording of changes in the quantity of dirt in total rock mass, as well as the integration of the newly developed system in the powered roof support control are described. For determining loading of the longwall conveyor by the swinging feeder, it is proposed to use the algorithms and methods of machine vision, added with a camera of projection of light marker net on the rock mass surface. The method of detection of variation in composition of rock flow is proposed to be implemented through automated measurement of gamma radiation in rock flow and comparison of the measurement with the control value. The concept of a versatile adapter is developed, and the control system architecture and automated operation algorithm are presented for the longwall top coal caving technology.

Some criteria are justified for selecting coal waste dumps suitable for heat recovery as a case-study of solid mine waste accumulated in the Donbas. These criteria involve geodynamics-position of a dump relative to the boundaries of an active geodynamic zone, as well as air dynamics-gas permeability of rocks in this zone and methane concentration in air entering the dump. It is shown that young and medium-age dumps situated within the boundaries of closed unflooded mines can contain mixture of air and gas with an explosive concentration of methane. The model of changing the role of mine methane in generation of the heat field in a self-heating dump is described. The model uses the idea that methane can both reduce the oxidation rate in coal waste and intensify their combustion efficiency. It is proposed to undertake geodynamic and gas dynamic ranking of coal dumps to determine their suitability as heat generators. The justified criteria can be used to develop a heat recovery technology for coal dumps.

The authors discuss the influence exerted by reagents-regulators on selective modification of spectral-kinetic characteristics of unrecoverable diamonds with anomalous luminosity to ensure their complete and selective recovery in X-ray luminescence separation. The parameters of kinetic stability are determined in emulsions of luminophore-bearing modifiers, and the reagents-regulators that cause no worsening of attachment of the modifiers at the surface of diamonds are found. It is shown that reagents-regulators of different classes (derivatives of alkyl/aryl phosphonates, aliphatic alcohols, bifunctionally modified derivatives of carboxymethyl cellulose, ionic and non-ionic nitrogen-bearing polymers, short-chain aliphatic amines, complex reagents) substantially decrease attachment of luminophores at the surface of hydrophobic minerals of kimberlite and prevent thereby their recovery to separation concentrate. The influence of reagents-regulators on the spectral-kinetic characteristics of the applied luminophore-bearing modifiers and treated diamonds is determined. The reagents-regulators suitable for the use in the modification technology without subsequent unwanted correction of spectral characteristics of diamonds are selected.

Flotation involves two forms of sorption using both a collector or a composition of collectors. Effect of the two forms of sorption of a collector can be assumed as a synergy of two reagents-collectors. In this case, flotation runs under conditions of hydrolysis of the reagent or its dissociation. Selection of a reagent mode means creation of condition for the two forms of sorption on a mineral surface. Activation of flotation by cations of metals, catalytic oxidation of xanthate form a sorption layer represented by the chemically or physically adsorbed reagents or by their derivatives. Each form of sorption plays a part in particle-bubble attachment. The first form of sorption aims at enhancement of hydrophobic properties of a mineral to be recovered, and the second form removes the kinetic constraint in the particle-bubble attachment. The strategy of selecting combinations of collectors to reach their synergetic effect in flotation is developed and proposed. Each collector performs its function in the particle-bubble attachment. Enhancement of hydrophobic properties of a mineral, or increase in the density of adsorption of a reagent at its surface results from the fulfilled condition of either chemisorption or physisorption of a reagent or a composition of reagents. It is shown that the properties of the second form of sorption are determined from the mechanism of work of a physically adsorbed collector.

The authors describe the results of leaching of Cu, Ni, Fe and S from copper-nickel ore mill tailings. The lab-scale testing conditions simulated in-situ capillary rise of solutions to ground surface. The leaching agents were water and water solutions of hydrogen peroxide at concentrations of 0.5, 1.0 and 10.0%. Aiming to activate native microorganisms, some columns were introduced with bacteria extracted immediately from the test mill tailings. In the other columns, in order to increase population of native bacteria directly in rock mass, conditions to stimulate their growth were created. The growth in the number of bacteria was observed in the ore mill tailings. The rates of extraction of iron, copper, nickel and sulfur in liquid phase differ depending on the composition of a leach solution.

The modified surface of sulfide minerals (arsenopyrite and antimonite) after bio-treatment with bacteria Pseudomonas Japonica is studied using electroacoustic spectrometer Dispersion DT-310, scanning electron microscope Tescan Vega II SBH, digital technologies and DSA20 EasyDrop unit. It is found that bio-treatment leads to substantial hydrophilization of the mineral surface, which is confirmed by an increase in the wetting angle by 40-50° and in the work of adhesion by 2 times. It is found that the electrochemical properties of the mineral surface also change, including the sign reversal of the ζ -potential and the increase of the electric conductance by an order of magnitude. The scanning electron microscopy proved adsorption of the bacterial cells at the mineral surface. The proof tests confirmed efficiency of the bio-treatment and show reduction in flotation of sulfides by 15-17% in their joint feed with xanthate. The studies display the promising nature of the micro-biological treatment of sulfides before selective flotation.

The research focuses on processing of copper-nickel alluvial sand wastes at the Verkhnee deposit, Norilsk Industrial District. In the sand wastes, the size category of- 100 µm is chosen, with the nickel and copper contents of 0.32 and 0.22%, respectively. The material constitutions of the initial sand waste and experimental samples were examined, and the optimal mode of their processing by a combination of low-temperature roasting with ammonia sulfate and bio-leaching is selected. The sand samples were mixed with ammonia sulfate and roasted, then the roasted mix was leached in water for 40 min with continuous stirring at a rate of 230 min^-1, and the remained was subjected to bio-leaching using iron-oxidizing bacteria. The maximal recovery of metals is achieved at the temperature of 400 °С and at a sand and ammonia sulfate mass ratio of 1 : 3: nickel recovery was 73.2% and copper recovery was 71.6%. Bio-leaching produced additional recovery of more than 20% of metals. Thus, through recovery of nickel and copper reached 95.4 and 88.0%, respectively.

The objective of this study is purifying kaolin ore collected from Djebel Debbagh deposit, situated in eastern Algeria by the utilization of a multigravity separator. The chemical, mineralogical and microscopic analyses were carried out. These analyses reveal that the kaolin ore contains kaolinite as the main mineral contaminated with manganese considered as an impurity in this case. This last reduce significantly the quality of this kaolin and consequently limit its use as raw material in several industries. Three variables, namely, drum velocity, wash water flow rate, and shake amplitude of the Mozly multigravity separator were chosen for the analyses of their influence on the content, yield and recovery of manganese in mill tailings. The Box-Behnken designs and the response surface methodology were used. After optimization of the process variables, the maximal values of Mn content, yield and recovery were obtained. The predicted results were consistent with the experimental data, confirming the model correctness and the effectiveness of the parameters adjustment in MGS for manganese removal from kaolin.

The practical application of manmade geochemical barriers in treatment of waste water in the mining industry is described. The studies of efficiency of natural and modified minerals in reduction of concentrations of heavy metals in mine waste water and in model solutions have positive results. The technical aspects of creation of manmade geochemical barriers are examined, namely, materials, sizes and designs aimed at enhanced efficiency and extended service life of the barriers. The geochemical barriers can be integrated in process flowsheets of operating mines, and are suitable for the independent use in closed mines where the cost of sophisticated waste water treatment systems is too high.