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The authors developed a pilot project to test different preparations of cemented rock fill, determine the appropriate mix design, and check necessary mix strength. The article presents the required resistance studies and the research method used to determine feasibility, cost performance and increased mine productivity and safety. The study achieved a resistance peak of 1.6 MPa, reduced dilution of the ore, and increased pillar stability.

The authors analyze the control circuit of the work process-related parameters of a hydraulic impactor with the piston retention before the back stroke phase. Retention is implemented via the throttle control of pressure in the hydraulic cell of the slide valve. The physical model of such hydraulic impactor is tested, and its energy characteristics are determined. The tests included re-tuning of throttles and slide homing spring, and variation in fluid flow rate. The article presents oscillograms of the hydraulic impactor dynamics and the slide performance versus throttle parameters, fluid flow rate and the spring pre-tension. The curves of the hydraulic impactor energy, retention pressure and fluid flow rate illustrate the energy adjustability using the proposed performance control circuit. The oscillograms of the slide motion during its work cycle are plotted, the features and shortages of the process are determined. The proposed design of the throttle valve provides the steady-state performance of hydraulic impactors.

The authors discuss the issue of engineering a special gear to change the power fluid pressure in hydraulic fracturing of strong rocks. The article describes the operation of the gear on the basis of implemented laboratory tests, and proposes the ways of eliminating deficiencies. The size and shape of choke grooves for the careful switching of the control valve subject to the power fluid flow rate are determined. The hydraulic circuit of the jet-control slide-type valve is developed. It allows improved accuracy and precision of the valve switching.

The influence of phase transitions in moist and salt-containing soil on freezing process is analyzed. The effects connected with the crystallization heat of pore water under negative temperatures and with the crystallization heat of salt when the eutectic point is reached are discussed. The conclusions on reachability of the eutectic point in artificially frozen strata above saline are drawn. Using a mathematical mode of heat processes in artificially frozen clay containing the common salt solution, the influence of the offset of the eutectic point on the temperature field in the frozen ground is analyzed.

The authors describe the integrated studies into the influence exerted by nonequilibrium low-temperature plasma of dielectric barrier discharge in air under normal conditions and pressure on the acid-base, adsorption and flotation properties of natural iron sulfides (pyrite and arsenopyrite). The studies aimed to correlate the plasmachemical treatment parameters with the physicochemical and process properties of sulfide minerals. Using the Hammet indicator method, it is found that plasma treatment strengthens acceptor properties and weakens electron donor properties of pyrite surface, as well as weakens acceptor properties of arsenopyrite. Adsorptive properties of pyrite relative to the electron-donor butyl xanthate grow, and, as a consequence, flotation activity of the mineral improves. In case of arsenopyrite, the adsorptive properties and flotation activity decrease. It is shown that the low-temperature plasma pretreatment of minerals reduces arsenic yield in flotation froth by 10-11% at the reduced arsenic content of concentrate by 0.71-0.78%.

A new device designed for wet magnetic separation-magnetic hydrocyclone-allows separating magnetic fraction from a fast and curved flow of pulp. The advantages of the magnetic hydrocyclone are the high specific output and the design simplicity which governs reliability of the device. The pattern of calculation of the magnetic hydrocyclonage performance represents an estimation of separability of magnetic fraction depending on the device geometry, variation in the magnetic field parameters, flow velocity and the physical parameters of the particles. The processing performance from calculations is compared with the results of the magnetic hydrocyclone testing. The proposed device is recommended to be included in the processing flow chart for ferruginous quartzite and other types of ore with the pronounced magnetic properties. Inclusion a magnetic system allowing higher magnetic induction up to 5-10 Tl in the flow chart makes it possible to extract weakly magnetic minerals.

The article describes the experiment on the upward percolating mass transfer by water solution according to the natural mechanism of movement of solutions toward ground surface with water evaporation in atmosphere. Useful components settle out from the solutions and concentrate on the evaporation barrier. The experiment simulates a complete cycle of processes for flotation tailings of complex ore: feed of solutions in boreholes from surface to bottom of a tailings body; spreading of the solutions in the tailings body; capillary ascent to the surface; settling out and concentration of useful salts on the evaporation barrier. The usability of this approach and some parameters of the mass transfer process can be found from the relevant research.

Using a laboratory model of a vertical centrifugal breaking machine, the milling efficiency of ore having different Mohs hardnesses is found. The rational structural and operating parameters of the breaking machine are determined for such ore materials. The data are included in the project documentation development for manufacturing a pilot vertical centrifugal breaking machine VTSI-12.

The optical, electron scanning and laser microscopy methods produced new experimental data on the adsorption layer generated by the chelating agent MDTC and hogweed extract on the surface of sulfide minerals in composition of complex ore. It is found that MDTC selectively attaches to chalcopyrite and forms a stable and water-insoluble compound with copper, which uniformly covers the whole surface of the mineral. It is determined for the first time that at the surface of pyrite, intense formation of dark-brown crystals of MDTC oxidation products takes place-dimorpholinethiuram disulfide which is chemically adsorbed at the mineral and is resistant to multiple washing-off in water. Morpholine dithiocarbamate does not interact with the surface of arsenopyrite and scheelite, and does not form stable phases with the components of these minerals. Hogweed extract does not desorb MDTC and is observed on the pre-adsorbed collector in the form of a fine bluish film washable off with water. At arsenopyrite and scheelite, a few separate and fine spots of hogweed are found.

A brief description of coal resources in Transbaikalia is given. The issues of thermal and hydrochemical modification of coal from Apsat deposit are discussed. The usability of carbonization, gas-steam activation and alkaline treatment of low-caking coal for the improvement of coal adsorption capacity is determined. The proposed technology of Apsat coal preparation and dressing includes crushing, screening, carbonization and steam activation. The characteristics of the initial and treated coal are presented. The main physicochemical properties of the produced carbon adsorbents are determined. The coal modification parameters are identified. The computer-aided modeling of activated carbon adsorbents based on the quantum-chemical interaction of particles is described. The application areas of high-quality adsorbents in mining waste treatment are specified.