Home – Home – Jornals – Journal of Mining Sciences 2017 number 6

The article addresses constraints of hydraulic fracturing application to enhancing preliminary degassing of coal beds. Decisions on geometrizing a hole interval by cemented mixture with cross fracture initiator are presented. An original conveying system for equipment in hole and a robotic hydrofracturing device for hard coal roof and floor are developed. The proposed hydraulic fracturing fluid with low-density proppant allows making fractures ensuring high-rate methane flow.

The article describes a safety control system for water-soluble mineral mining in complicated ground conditions. The system is based on geomechanical interpretation of surface and underground seismic monitoring. Mathematical modeling of water-impervious strata takes into account the whole set of mine-technical and geological factors determined from the seismic observations. It is shown that seismic-geomechanical monitoring allows stress state control in waterproof strata, which ensures prompt decision-making on extra protection and minimizes accident risks.

3D geomechanical model of 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 laboratory-scale experiments is formulated and solved.

Stress state of rock mass during fully mechanized longwalling in dislocation zone is analyzed. In focus is the variant of crossing the dislocation zone with disassembling the fully mechanized longwall system and its re-assembling in a new room. Stress redistribution in coal and host rocks when heading approaches dislocation and in post-dislocation mining from the new assembling room is determined.

The authors present the procedure and data of many years-long geodynamic monitoring of the ground surface displacements in Uzelga and Talgan mining areas. Despite similar geological conditions, the difference in the types of the protected objects on the ground surface conditions 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. The results of the implemented geodynamic activity assessment include vectors of general spatial displacements of observation plugs and curves of compression-tensions and shearing strains. It is determined 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.

At mineral deposits and in the intercontinental areas of the Earth, subhorizontal tectonic compression stresses are anomalously high. Many mineral deposits occur within subsurface ring-shaped morpho-formations. The authors solve the problem on stress state in a ring structure at representative stages of its evolution. It is shown that sublateral compression in the ring structure, in particular, at mineable depths, is very heterogeneous, unstable and can considerably exceed stresses due to overburden rock mass weight. The calculated results are compared with the laboratory and in situ data.

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.

The authors offer a simplified two-zone model to describe fluid flow in steady-state horizontal holes with multi-stage hydraulic fracturing and present the analytical solution in order to calculate sizes of hydrofractures. The new procedure to determine size of multi-stage hydrofractures in horizontal holes is tested using field data on China deposits. The calculation results prove the efficiency of the procedure in the determination of steady-state conditions. The procedure can be used in optimization of hydraulic fracturing.

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.

The article addresses the issue of development of a large-diameter (from 500 m and more) rotary drill tool (drill bit) for exploration of placers in permafrost. It is shown that at the contact of drill bits and bottomhole, permafrost thaw takes place with the further adhesion and congelation of the drill tool and hole walls, which degrades coring. The dependence of heat emission at bottomhole on cutter configuration radius on drill bit is determined. The developed design of a drill bit ensures efficient destruction of bottomhole with minimized heat emission, and a prototype drilling assembly is manufactured for large-diameter rotary drilling. The in situ test data are presented.

Different modes of advance of a driven 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 authors describe laboratory tests of hydraulic fracturing with proppant made of aluminosilicate microspheres ASPM-500 in combination with acid treatment for shallow fracking in thermal recovery of heavy oil. It is illustrated that application of aluminosilicate microspheres to local fracturing of rocks is a promising line of development of hydraulic fracturing technologies.

It has been found to be economically expedient to develop the west wing reserves of Oktyabrsky Mine by cut-and-fill method with cemented backfill of primary stopes and dirt fill of secondary stopes. This method shows better performance in terms of ore loss and dilution as compared with the current mining system at the same quality of ore produced. Feasibility study of the two variants of process design in the full cycle of mining, processing and recovery of primary metal (nickel) and associated metals (copper, platinum, etc.) shows that the proposed mining system allows higher profit per unit of ore mining and processing.

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 fiber-reinforced shotcrete lining with surface support 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 dry-mix shotcreting is calculated in terms of Artemevsk Mine.

The investigation in volume density of titano-magnetite ore of the North orebody of Gusevogorsky Deposit is reported. It is found that the volume density is interconnected with the iron content of ore. Based on the block modeling, the authors predict variation in the volume density and total iron content for deep level ore in Northern open pit mine of EVRAZ KGOK. The prediction data are applicable in geological and process designs.

Using the scanned laser microscopy, the authors obtain 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, which allows substantiating the method of selective production of antimonic concentrate from complex gold-bearing arsenide ore by new reagents and enables optimized selection of reagent regimes.

The collecting ability of desorbable species (DS-species) of carbonic acids is analyzed. The spreading velocity and surface pressure of some fat acids are correlated with their collectability. It is found that an increase in the hydrocarbon chain length to a certain limit results in the higher collectability of carbonic aids, which correlates with the high spreading velocity of derivants of the acids on water surface. The cause of reduction in the collecting ability of short-chain collectors is discovered. It is shown that an adequate criterion of fat acid collectability can be the surface flow thickness of the agent’s DS-species film. The flotation performance with the mixed chemisorptions and physisorption coat and with the coat represented by chemical adsorption is estimated. The causes of the decrease in the valuable component recovery and in the concentrate quality without the physical form of reagent adsorption at a mineral surface are revealed.

The article describes sequential leaching of gold-bearing ore of the residuum. 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 three-stage procedure focuses on mobile forms.

The change in separation performance and in magnetic characteristics of separation products is traced along the processing circuit of Abagur plant at a laboratory scale in order to determine the limit content of magnetite iron in impurity aggregates in the concentrate. The wet magnetic analysis is carried out in the field of H = 175 kA/m, and the magnetic characteristics are determined in the vibration magnetic detector in the field up to 800 kA/m. The concentrate impurity is governed by the relative content of barren rock and ore aggregates removable in concentration at the given level of the technology.

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.

The article describes the instrumentation system designed for the synchronous recording of electromechanical emission and mechanical deformation parameters in lab-scale tests of rock specimens. Based on the data of implemented tests, the change in the structure and spectrum of EME signals at the pre-discontinuity stage in rocks is determined, and the failure prediction criteria are proposed.