Home – Home – Jornals – Journal of Mining Sciences 2019 number 6

The authors analyze the structure of the elasticity tensors and compliance coefficients in a special linearly elastic and transversely isotropic material with paradox behavior. The intrinsic moduli and states are found for the elasticity tensors if this material. The extreme values of Young’s modulus, shear modulus and Poisson’s ratio are determined. The characteristics of the nearest tensor of elasticity moduli are obtained.

The authors analyze the effect revealed at the Institute of Mining, SB RAS in the 1970s. This effect consists in a noticeable off-center displacement of the maximum normal pressure on the bottom of a conical pile when heaped. The new experimental data are presented. The stress-stress analysis of the pile between two parallel smooth plates is solved using a 3D discrete element method. The calculations prove the indicated effect.

In the current study, uniaxial compressive strength, Schmidt hammer and Sonic velocity tests are performed on NX size rock core samples from Sakesar and Namal formation limestone. Least square regression analysis is used to develop any possible correlations between the destructive and non-destructive test results. Empirical models, for predicting the uniaxial compressive strength of rocks by using the rebound number and P-wave/S-wave velocity, have been developed and evaluated. Analysis shows that the empirical model for predicting UCS with Schmidt hammer rebound number is more reliable over a wide range of strength values for both the formations. Whereas the models that uses P-wave/S-wave velocities is reliable particularly when the strength values are low to medium.

The collected data on long-runout rockslides induced be large-scale underground blasts are presented. The critical conditions of the rockslides are determined as a function of the dynamic impact, rockfall volume, as well as the slope height and gradient. It is shown that the main condition for the mobile rockslides is their volume exceeding 10⁶-10⁸ m³. A collateral effect for rockslides in case of smaller volume of 10⁶-10⁷ m³ is the presence of an acceleration phase at the slope toe and the absence of a counter slope. The relations of the avalanche front range, rockslide volume and failure height are given. It is mentioned that the avalanche range is associated with their composition, in particular, rock-and-ice or rock-and-snow avalanches feature increased mobility starting from their volumes of 10⁵ m³. A brief review of theoretical and modeling studies intended to explain the reduced friction in large avalanches is provided.

The measurement data on seismic load parameters induced by massive blasting in surface and underground mines are presented. The maximum amplitude of seismic vibrations at the probable depth of potential sources of high-magnitude stimulated-tectonic earthquakes is calculated. These estimates and their comparison with the precision deformography observations show that residual displacements along faults at seismic depths under the impact of massive blasts in surface mines are not more than dens-hundreds microns. The seismic data demonstrate insufficiency of these impacts for initiation of high-magnitude earthquakes.

Three influences on physical modeling results of unstable dynamic displacements along fault edges under triggered relaxation. The fault filler is assumed to be quartz sand placed in-between moving tiff and rough plates. This quartz sand interlayer is subject to variation in compaction, to relaxation from stresses and to a burst air flow across the interlayer to simulate gas rush in the fault. The relaxation periods in the compact sand packing under the influence of the gas flow are determined.

In this study, the best possible location for an air deck in an explosive column during a surface blasting operation for the most efficient rock fragmentation is described. Volumes of air decks are proposed for the optimization. This study aims at helping guide blast engineers to easily apply an air deck in a surface blasting operation.

The current situation and development trends in the biological degassing of coal are reviewed. It is shown that methane desorption is a consequence of rock mass destruction by activity of microorganisms and releasing bacterial metabolites. The influence of microorganisms on coal as a function of a prevailing microbial community and its variety, access of oxygen and nutritious substrates is observed. Advancement of the biological method for coal field degassing based on the methanotrophy is discussed.

Specifications of domestic and foreign shearers are given. The problem is formulated for optimizing web width of a shearer by the maximum capacity criterion with regard to geological and technology factors. The analytical solution is obtained for the problem using the approximating linear functions of the sloughing factor and the web width. The influences of the optimal web width of shearer are analyzed, and the related recommendations are made. The extremal curve of methane relase from broken coal is shown, and the allowable capacity of face by the gas criterion is tested in longwall 5214-1 in the Yalevky Mine of the Kuznetsk Coal Basin.

Layouts of reloading points in the cyclical-and-continuous technology for deep-level surface mining are analyzed. The innovative structure of a reloading point involving dump trucks drivethrough passing has been proposed; the structure will make it possible to increase reloading point productivity, cut the costs for rock mass extraction, and reduce the time of motor transport maneuvering. Dependence of general funds saving for overburden rock extraction upon the open pit depth while constructing a reloading point with the drivethrough passing comparing to a dead-end unloading of various-capacity dump trucks has been determined.

The classification of the methods available for diagnostic of mining machinery mounting groups with roller bearings is considered with indicated advantages and disadvantages. The model is constructed to describe formation of shock pulses in roller bearings when different defects are generated in them. This model is suitable for the availability monitoring of the machinery mounting groups. The applicability of wavelet transforms instead of the standard fast Fourier transform to random processes and vibro-acoustic signals is tested for the detection of defects in manufacture and operation of mining machines.

Sawing of natural stones with diamond-impregnated circular saws is extensively implemented in stone processing plants in variety of applications that include sawing, cutting, splitting and trimming. Hence, thecost of diamond saws and energy have become important input in terms of estimating the hourly areal slab productions (HASPs) from the standpoint of effective cost analyses,feasible and sustainable designing of stone processing plantsprior to reaching a decision forthe investment. This study aimed at estimating the HASPs of the machines with circular diamond saws during the dimensioning of marble blocks quarried in Mugla (Turkey) Region. Thus, the models were generated to estimate the HASPs by artificial neural networks (ANN) and regression method (RM), based on Shore and Schmidt hardness values of rocks. Also, HASPs were acquired through in-plant measurements in order to justify the HASPs estimated by ANN and RM models. The analyses of the models generated using ANN proved to yield very strong consistencies with HASPs measured in the plants. Hence, the HASPs canbe estimated reliably by the ANN modelswhich also may be considered as a tool in designing ofnatural stone processing plants based on rock surface hardness.

The influence of non-ionic compounds in combination with sodium oleate on the contrast behavior of flotation response of calcium minerals is investigated theoretically and experimentally. The flotation and adsorption analyses are carried out with monomineral fractions of calcite and scheelite, while the flotation process analysis is conducted with an ore material screened into size grades of - 44 and - 15 μm. The process conditions of the highest difference in adsorption of oleate and contrast in extraction of scheelite and calcite are found. the conditions of the maximum depression of calcite in the rougher flotation circuit are determined.

The influence of nitric, sulfuric and chlorohydric acids on the morphology, composition of elements, structural and chemical transformation of mineral surface and leaching of eudialyte concentrate is studied using a set of the modern analytical techniques. Specific features are revealed in the nature and degree of eudialyte decomposition under the influence of different acids. These features affect the intensity of removal of basic cations of Al, Na, Ca, Mg, K, Ti, Mn, Fe, Sr and Zr from the mineral surface. The behavior and regular patterns in the formation of silica gel and secondary phases during dissolution of eudialyte concentrates are examined. Sulfuric acid, which ensures the highest extraction of Zr and rare earth metals in pregnant solution, contributes to maximum formation of silica gel and considerable quantity of gypsum and insoluble sulfates, which results in high loss of Zr and rare earth metals. The use of nitric and chlorohydric acids reduces the loss of Zr and rare earth metals by 2-5 times.

The theoretical and experimental substantiation of the behavior of ferrous sphalerite in magnetic separation is given in terms of the Gorevka deposit ore. In sphalerite of this deposit, the content of isomorphous iron ranges as 4-9%. The Mössbauer spectroscopy showed the singlet and two doublet lines of iron, demonstrating separate arrays of iron atoms in sphalerite lattice, with formation of Fe-Fe pairs and clusters of three or more iron atoms. It is found that distribution of iron in sphalerite into three forms coincides for magnetic and nonmagnetic products of zinc concentrate separation. It is determined that magnetic separation undivides sphalerite grains by the isomorphous iron content but is governed by the genetic features of the deposit formation-association of sphalerite with magnetic minerals (pyrrhotine and siderite) and the absence of such associations in galenite.

The article presents the research findings obtained in deep integrated processing of rebellious high-potassium aluminum silicates from the Kalyum deposit within the Synnyr alkaline massif-synnerite-with production of alumina as well as potassium and magnesium sulfates. The introduction of magnesium-bearing mineral-dolomite-as an additive at the stage of thermochemical decomposition of the acid-resistant minerals in the initial raw material (K-feldspar group) provides improved efficiency of the processes due to cheapening of baking, increased marketable production and reduced solid waste. It is found that leaching of activated synnerite by 60% sulfuric acid promotes deposition of the silicon component as amorphous silica, which facilitates the further processing of pregnant potassium-, magnesium- and aluminium-bearing sulfuric acid solutions with marketable production.

The modeling procedure is developed to describe heat-exchange processes in outdoor summer storage piles of frozen coal produced in winter. This procedure takes into account thermophysical properties of coal and the pile bottom soil, pile structure, climatic factors and presence of a heat-insulating coating over the pile. In terms of central Yakutia, it is shown that maximum transition of coal from frozen state (piling in January-Marhc) top thawed condition at the pile height more than 5 m will make 25-35% by the end of the warm season (beginning of October). Application of simple and available heat-insulating materials can reduce thawing intensity by up to 2 times. Natural cold weakens the aggravating effect of oxidizing processes on coal quality in long-term storage of coal and its shipment to remote and hard-to-reach places.

The geophysical investigations are carried out at the Kangalass open pit coal mine using the round penetrating radar and electrical tomography. The main frost effects in rock mass and in water retaining dam are described. The investigation procedure is developed, and the wave fields are characterized. The GPR surveys aimed to reveal water invasion zones in a rock block to be blasted and to trace dynamics of a seasonal thawing layer are presented. The integrated analysis of GPR and electrotomography data is performed tod determine adverse freeze-and-thaw processes at the dam bottom. Applicability of GPR in prediction of unfavorable freeze-and-thaw activities is demonstrated.