Vol 53, No 6 (2017)

The problems preventing the use of mine hydraulic fracturing for stimulating the preliminary degassing in coal seams are considered. The solutions are presented for sealing the borehole interval by solidifying composition with initiator for transverse fracture of rocks. An original system for transportation of equipment along the holes and a robotized device for hydraulic fracturing of roof-and-floor selfsustaining rocks of coal seam are designed. The working fluid with a low-density proppant is proposed, which ensures creation of fractures with a high rate of methane migration.

3D geomechanical model of the Vorkuta Mine, Pechora Coal Basin, has been developed and implemented numerically. By the data on dynamic events recorded by stationary seismic stations, tomography of the study object is performed, and velocity of elastic waves is recovered in the illuminated area of the object. The boundary value inverse problem on horizontal external stresses by stress distribution found using empirical relations between elastic wave velocities and stresses determined in the laboratoryscale experiments is formulated and solved.

The procedure and data of many years-long geodynamic monitoring of the ground surface displacements in the Uzelga and Talgan mining areas are presented. Despite similar geological conditions, the difference in the types of the protected objects on the ground surface commands different variants of the procedure for each deposit. Some points of reference surveying network and observation plugs are re-fixed using the satellite data, digital elevation meter and electronic tachometer, and characteristics of trends in modern geodynamic movement induced by a displacement trough are obtained. As a result of the implemented geodynamic activity assessment, vectors of general spatial displacements of observation plugs and curves of compression–tensions and shearing strains are determined. It is found that rock mass deformation has a discrete mosaic pattern. The conclusions are generalized, and the hypotheses are made on the further deformation of the ground surface.

In this paper deformation wave is studied on the basis of continuous phase transition theory. Relative shear strain is taken as an order parameter. The potential energy is obtained by analogy with the Ginzburg–Landau expansion of free energy. Hamilton’s variational principle is used to obtain the motion equation by which several types of deformation waves can be modeled. The results show that the proposed model is effective in modeling deformation waves.

Efficiency of energy-based criterion of volumetric rock destruction in estimation of drilling technology is theoretically validated and experimentally proved in in-situ rotary–percussion drilling in mines in Russia. The criterion is adapted to the performance of various drilling units by means of introduction of empirical coefficients for transformation of drilling energy intake to the relevant energy characteristics of stress rock fracture in face zone. The mathematical description of the criterion of minimum energy intake of rotary–percussion drilling depending on stress state and physical properties of rocks, and on force of rotary–feed mechanism is presented. The authors introduce a new geomechanical notion—factor of topological connection of rocks and give its analytical expression using experimental uniaxial compression and uniaxial tension strength of rocks, required in the design and improvement of rotary–percussion drilling in different geological and geotechnical conditions of mining.

Different modes of advance of a pipe with a soil plug under rectangular impulse are investigated numerically and analytically with regard to dry friction between the pipe and plug and between the pipe and external stationary medium. The two model solutions are compared with and without regard to the pipe and plug elasticity. It is shown that elasticity of the pipe and plug is neglectable in case of a long-duration impulse.

The result of laboratory tests on permeability of fractures with proppant made of alumosilicate microspheres ASPM-500 in combination with acid treatment for shallow fracking in thermal recovery of heavy oil are presented. It is illustrated that use of alumosilicate microspheres in local fracturing of rocks is a promising line of development of hydraulic fracturing technologies.

The state of mining in Artemevsk Mine is analyzed, and the current and recommendable support designs are described. In unstable rock mass, it is possible to replace heavy and laborious steel frame support by less expensive and lower labor-intensive shotcrete lining with surface reinforcement without reduction in load-bearing capacity of the support. The variants of arrangement of shotcrete production plant are discussed, and the economic efficiency of the proposed wet-mix shotcreting is calculated in terms of Artemevsk Mine.

Using the scanned laser microscopy, the new experimental data on the influence exerted by a phytomodifier represented by tannin on adsorption of a compound collector represented by modified sodium diethyl dithiocarbamate at arsenopyrite and stibnite were obtained, which allowed substantiating the method of selective production of antimonic concentrate from complex gold-bearing arsenide ore by new reagents and enabled the optimized selection of reagent regimes.

Sequential leaching of gold-bearing ore of the residuum is described. The interconnection between rare earth elements and their mineral matrix is defined. The mobility of REE in the initial ore and during hypergenesis is assessed. Two kinds of REE are revealed: fine monazite cerium–neodymium crusts in iron-bearing minerals and dense monazite pockets in titanium-bearing minerals. The five-stage sequential leaching procedure allows more detailed distribution of elements in the rebellious matrix while the threestage procedure focuses on mobile forms.

Underestimation of raw material reserves contained in gold mining waste dumps results in tense socio-economic situation in gold mining regions. Efficient management of gold mine waste is only possible with the new and sound technologies of waste preparation and deep conversion with a view to recovering valuable components. Aimed at creation of such technology, the large-scale theoretical and experimental research has been undertaken in order to study the nature and rate of influence exerted by basic process factors on migration and concentration of gold particles in gold mine waste.

The test bench has been designed to subject specimens of geomaterials to loading by torsion and longitudinal compression with the simultaneous multiple weak impacting. The measurement system contains sensors for static and dynamic measurements of strains. The tests experiments included cyclic torsion of mixed gypsum and quartz sand specimen. The static and dynamic strains were measured, and the velocity of elastic wave in organic glass was determined.