Home – Home – Jornals – Journal of Mining Sciences 2014 number 6

The authors offer an approach to estimating deformation of rock mass around a stope (zonal disintegration) at deep levels. The algorithm of geomechanical condition of rocks is developed, and the ranges of stresses and strains in the zone of influence of a stope are identified. It is shown that when Young modulus in the vicinity of the stope is higher than inside the rock mass, displacements of the stope perimeter are lesser.

The article describes the method of estimating potential instability of natural and man-made slopes based on the generalized Mohr-Coulomb failure criterion considering stress-strain state of rocks. The most probable sliding surface is defined by step-wise iteration using the method of local variations. The authors emphasize the requirement to assess the condition and behavior of a landslide body during dynamic displacement in order to spot its final position, and adduce examples.

The article presents results of numerical experiments performed to evaluate the effective rheological properties of a mixture of a fluid with solid particles. The numerical simulation of the Couette and Poiseuille flows shows that in the both cases, the effective viscosity and non-Newtonian properties of the suspension coincide to the accuracy of standard deviation. The authors define the area of applicability of Newtonian fluid model to modeling fluid and proppant mix and determine conditions for plugs at high concentrations of proppant.

The article reports numerical investigation of radiation near-zone of a downhole unbalance vibration exciter. It is found that vibration intensity is spatially variable and depends on vibration frequency. The authors specify the vibration exciter work mode required to ensure maximum impact on coal-and-rock mass in the vicinity of degassing holes at the limited power of the vibration exciter drive.

Using the model information and in situ data on hydrofracturing in an oil and gas reservoir of the Bakken Formation (USA), potential of locating hypocenters of microseismic events concurrently with determining parameters of velocity anisotropy of seismic waves in rock mass is analyzed. It is shown that inclusion of anisotropy in the analysis improves accuracy of spatial location of microseismic event hypocenters and increases validity of estimation of the fracturing direction.

In focus are special cases of distortion of buildings when heavy structural deformations were visually observed though instrumental monitoring showed low strain values. The experimental laser scanning of such deformations exhibited complex deformation patterns in horizontal planes of buildings. Aimed at defining the causes of the nonlinear deformation of buildings and structures and preventing relevant accidents, the integrated monitoring technology is offered based on taking account of stress-strain state and block structure of the building-underlying rock mass.

The authors study the influence of external pulsed low–energy impact (blows) applied to different rock specimens exposed to loading up to failure on the electromagnetic radiation record layout.

The article describes numerical modeling of growth of five successive hydraulic fractures in the direction transverse to the well, in plane and axisymmetric elastic problems, under assumption of perfect breakdown fluid. The zone of influence of the existing created fractures on the newly initiating hydrofractures is defined, and the pressure for a new fracture to grow is evaluated. Parameters governing distortion of fractures are determined. The calculations in the framework of the plane and axisymmetric problems are compared.

This is the first attempt to analyze theoretically large-scale blasting effect on rocks in complex ground conditions, including selective breaking. The authors consider utilization of the direction effect of blast energy using different charge designs, which is implemented as replacement of large diameter charge with a round of smaller size charges with equivalent total energy. Under discussion are new options of blast energy transfer and distribution in rocks.

The problem of rock abrasivity testing consists in the incompatibility of data obtained using different methods. To this effect, the author offers method for qualitative evaluation of potential abrasivity of rocks using their physico-mechanical properties arranged on the canonical scale of structure-and-hierarchy representation.

Under tension of cable interacting with ground, implementation of the effect described by the Euler formula for a tensile cable that envelops a fixed support is experimentally proved. Model and field experiments show essential rise in the load-bearing capacity of earth anchors with flexible tendon-E-anchors, owing to this effect. Equipment for installation of the anchors is designed and trialed. Using DEM, a 2D problem on the efficiency of the new anchors as a function of direction of uplift force applied to the tendon is solved. The article illustrates application areas of E-anchors in construction and operation of engineering structures.

The article focuses on improvement of strength and wear resistance of tangential swivel cutters intended for high-productivity coal cutting at minimized energy input. It is proposed to reinforce cutters by hard-allow indenter-ellipsoid that has no stress concentrations and cuts rock mass by shearing. Tests of engineering samples of tangential cutters in Kuzbass mines confirm the analysis data on the design of the reinforcement insertion.

Procedures for calculating permissible gas-related length and output of a fully mechanized production heading considering nonuniform airflow over cross-section and lengthwise the longwall are described. Nonlinear relations are derived for methane concentrations and air leakage in mined-out area. It is proposed to assess a production heading output based on the gas-related permissible length of the heading and the coal cutting chart with a cutter-loader. It is found that increased gas content of coal and higher air leakage in mined-out area causes reduction of gas-related length and results in decreased output of production headings.

High-rate ore drawing with a single drawpoint requires stable structure of the horizon bottom in block caving of ore. Application of load–haul–dumpers conditions longer spacing of drawpoints, which worsens quality of ore drawing under caved rock. Adequate structures of trench bottoms of ore drawing levels are developed for LHD. To define mutual influence of the drawpoints, relations are set between the limit spacing of drawpoints along the length of the trench and the height of the caved level.

Toward efficient and optimized application of agents MTH and ETH, belonging in dithiazinanes, to flotation of gold from complex ores, the actual flotation tests were preceded by the analysis of complexing conditions in water environment and on pyrite surface with manually attached gold (FeS₂Au). The microscopic and spectral analyses of FeS₂Au surface after contact with MTH and ETH show organic S– and N–containing agents. It is found that selective gold recovery from gold-bearing material in flotation with MTH and ETH is conditioned by a number of factors that accelerate formation of low solubility compounds on the surface of gold particles. The analysis includes studying duration of mineral and reagent contact, optimal medium alkalinity, formation of oxidized film on the surface of Au⁰ particle, introduction of modifying agents that act as additional ligands as well as mechanochemical acceleration of complex formation. Mechanochemical treatment with introduction of low solubility ETH agent in a mill before copper sulfide gold-bearing ore flotation enabled increased gold recovery in the rough flotation concentrate and middlings by 15.9 and 4%, respectively. In this case, Au content in tailings was reduced by 0.15 g/t as against flotation experiments with butyl xanthate and its combination with ETH.

Considering lack of lithium, the authors believe it is advisable to analyze dressability and producibility of spodumene concentrates from mine waste, specifically from tailings of Transbaikal Mining-and-Processing Integrated Works. The analysis includes mineral, chemical and grain-size compositions of raw material, as well as the capacity of spodumene to be separated and recovered. These characteristics make the basis for developing the dressing technology and process flowsheet for the indicated type of technogenic (i.e. resulted from production activities) deposits.

By noncontact measurement of crystal surface charge and with specific–designed equipment, the authors examine effect of model water systems having various physico–mechanical properties on the value and sign of charge of diamond and zirconium crystals. Experimental substantiation is given to the applicability of products resulted from electrolysis of water to the controlled change of surface charge of diamond and minerals with close physical properties during their electric separation owing to the increased difference of electric properties of the separated materials.

The article reports data of analysis of surface compounds on galena, chalcopyrite and sphalerite. By X–ray photoelectron spectroscopy and IR spectroscopy, the authors find the oxidability series: PbS ≈ ZnS < CuFeS₂. Sphalerite has the largest amount of free water in the surface layer. The frother and nonfrother flotation experiments show that floatability of monomineral fraction of galena is higher in neutral medium at sulfhydryl agent concentration under 10–4 mole/l. In alkaline medium floatability of galena grows with increasing concentration of sulfhydryl agents, which degrades selectivity of flotation. Galena recovery is the highest with butyl xanthate and di-isobutyl di–thiophosphinate. Tests of adsorption use the method of isomolar series and nonfrother flotation conditions. Constants of adsorption velocity are calculated at different ratios of strong (butyl xanthate) and weak (thiocarbamate) agents for galena, chalcopyrite and sphalerite. If thiocarbamate prevails, the adsorption velocity constant grows, and so does recovery of chalcopyrite as against galena and sphalerite. The experimental results agree well with the data of production research of samples from Stepnoe and Rubtsovskoe polymetallic ore deposits.

The article presents research findings of testing adsorption of phytogenous collecting agents at the surface of gold-containing pyrite and arsenopyrite using UV spectroscopy, as well as analytical scanning electron, laser and atomic force microscopy methods. It is found that components of extracts of oak bark and umbelliferous plant foliage are selectively adsorbed at the sulfide mineral surface, which enables selective flotation of pyrite and arsenopyrite in gold-bearing sulfide ore dressing.

This study attempts to assess the contribution of entrainment and true flotation in the overall recovery by the laboratory tests performed on a natural complex sulphide ore, provided by la Compagnie Minière des Guemassa (Morocco), and the effect of two different collectors, Potassium Amyl Xanthate (PAX) and Sodium di–isobutyl di-thiophosphinate (Aerophine 3418A), on the two contributions. Overall recovery and true recovery were fitted to first kinetic model and modified flotation parameters were calculated to measure of flotation separation selectivity of chalcopyrite, galena and sphalerite over gangue and pyrrhotite. To estimate the entrainment, Ross method was the most suitable in the case of complex sulphide ore with high content of pyrrhotite. Trahar method overestimates the effect of entrainment.

The methodological approach to rehabilitation of disturbed lands in mining areas in accordance with the evolutionary descent program of soil formation on mineral substrates by generating a biologically active medium has been substantiated and approved based on the data of many–years monitoring of various objects.

The article reviews the experience gained in the integrated assessment of the environment condition the regions exposed to high industrial load, the basic approaches to satellite image processing and the sequence of analysis of natural components. As an example, the authors assess condition of a coal mining region in Kuzbass.

The authors discuss current condition of forests and lands in the neighborhood of Stary Oskol-Gubkin Iron Ore Integrated Works. The rate of change in the coverage area and condition of pinery between 1986 and 2012 is explored. The types and areals of change of forests are revealed. Using satellite and in situ data, intensity of auto–healing of open pit dump areas in the period from 1988 through 2012 is studied.

Experimental research is focused on the effect exerted by natural anisotropy orientation in some composites on the acoustic emission sensitivity of sensors. Acoustic emission is related with the angle of load application and lamination orientation in a composite. Based on cyclic test data, it is shown that the load application angle has significant influence on acoustic emission memory effect up to its complete vanishing. Considering the revealed mechanisms, the authors propose the method of stress-strain state control in mine design elements.

Karier multichannel measurement system is fitted with wireless displacement sensors that communicate via radiochannel and have independent supply, which greatly improves their portability and performance. The data transmission channel between an operator in the Information Acquisition Center and the open pit mine survey service facilitates on–line analysis and relevant decision-making toward safer mining.