Home – Home – Jornals – Journal of Mining Sciences 2021 number 2

The mathematical model of vertical penetration of a steel pipe in soil with a shock pulse generator is described. The influence of the external problem parameters on the attenuation of the shock pulse propagating along the pipe is described, and the process generalities are found. The attenuation law of the mass velocity amplitude in the shock pulse along the pipe during vertical penetration in soil is revealed.

The authors study the ground surface displacement in the area of Zhezkazgan copper ore field now subjected to extraction of ore reserves from rib pillars. The high-precision leveling procedure using digital leveling instrumentation and invar leveling staffs is proposed for the application in arrangement of a geodynamic test site at the settlements of Zhezkazgan and Lermontovo. The steel control survey points are firmly connected with rock mass by means of grouting. The observation results made it possible to detect and evaluate the ground surface displacements.

The author proposes a problem formulation for the capillary rise process when one of the capillary ends is connected to the atmosphere and the other end is put in a liquid-filled tank with walls subjected to vibrations. The calculations show that pressure surges essentially reduce the time of capillary imbibition. Given no vibration in the liquid flow from the tank to the capillary, the water rise height found from the numerical solution of the formulated problem coincides with the calculation from the Lukas-Washburn equation and agrees with the test data. The generalization algorithm for the problem to be applicable to capillary imbibition in porous media saturated with immiscible liquids is presented.

In this research, firstly, the literature review of the most kinds of toppling failure is presented, and then using the fictitious horizontal acceleration technique, an analytical approach is suggested for the stability analysis of block toppling failure. This method is compared with the Goodman-Bray method through a typical example. The results of the methods have an acceptable agreement.

The blasting experience in Zapolyarny Mine is described, and the actual oversized/undersized fragmentation of blasting from haulage drift is presented. The drilling-and-blasting pattern parameters provide insufficient fragmentation quality, which elevates the blasting cost and reduces its efficiency. It is shown that the actual oversized/undersized fragmentation agrees with the Kuz-Ram fragmentation model. This allows adjusting the calculation parameters of uniformity index for the prediction and optimization of grain-size composition in broken muck. Possible causes of oversized/undersized fragmentation are discussed.

The field investigation were planned and implemented in some of the coal mines at Central India. Based on the field investigations, the detailed parametric analysis was done with respect to sinkhole depth against each critical parameter. A sinkhole model has been developed by using statistical approach to understand the collective influence of all critical parameters and also to calculate sinkhole depth under different conditions.

The paper presents a case of a sinkhole located in a hard coal mine within the Upper Silesian Coal Basin in Poland and attempts to explain the causes of its formation. The calculations and analysis of geological and mining conditions carried out within the area of the sinkhole allowed to formulate conclusions that can support the decision-making process related to construction investments and environmental protection in the area of the decommissioned mine.

The theory of the lag modeling approach to optimizing design capacity of an open pit gold mine by the criterion of maximized integrated economic performance over the mine life is given. The geology of Brekchia gold field in the Altai Krai is described, and the open pit mine design is shown. The optimization results on the open pit mine design capacity by the integral criterion of maximum economic indices using the lag modeling approach are given. The influence of the market prices of gold on the optimized design capacity of the open pit mine is analyzed.

The authors address the problem connected with gradual rise of sludge level in Aikhal open pit mine. It is found that sludge level has been rising gradually in the course of underground mining under the safety crown meant to prevent inrush of watered mud from the open pit bottom to the underground excavations. The promising approaches to steadying of watered sludge to ensure safe and convenient underground mining are developed.

The study analyzes the influence exerted by the body, guide and their materials on the pull strength of electromagnets in electromagnetic hammers. The pull strengths of electromagnets without positive and negative poles are evaluated.

In order to ensure the safety of the autopilot system, this article analyzes the causes of motion blur from the perspective of camera imaging principles and uses the relationship between the coordinate systems to determine the position of a certain point in the three-dimensional space in the pixel coordinate system. Finally, the degree of motion blur is determined by calculating the displacement of the pixel points per unit time and assigning weights to them using a Gaussian function. The results show that the degree of motion blur increases from the center of the image to the sides, and it is positively correlated with the motion speed in general. This is used to determine the critical speed of safe driving, providing a way to improve the safety of the open-pit mining autopilot system further.

The study focuses on stability of particle-bubble attachment versus the size of particles attached to bubbles, design of a flotation cell and the input energy. The main force to tear away a particle from a bubble is assumed to be the inertia force conditioned by undulation of the gas-liquid interface. It is examined how the bubble surface oscillations influence detachment of particles. The oscillation amplitude is a function of the energy dissipation rate. The energy dissipation rate is determined using the methods of computational hydrodynamics in Ansys Fluent. The calculated sizes of particles produced in frother flotation with regard to coalescence in the froth bed agree with the existing and new experimental data.

The thermodynamic analysis and tests of minerogenesis under higher temperatures determine conditions of thermochemical decomposition of hydrophilic attachments on diamond surface. It is found that hydrophilic mineral attachments can be removed from diamond surface by combining thermal treatment of slurry at the temperature of 80-85 °С with electrochemical treatment of recirculated water, which enables required change in ion-molecule composition of water phase in the slurry. The hybrid conditioning technology ensures recovery of the natural hydrophobic behavior and floatability of diamonds and enhances performance of froth flotation of diamonds by 5.1%.

The adsorption properties of electrochemically and thermally modified saponite relative to heavy metals are analyzed. The tests have found the efficient use and regeneration parameters of the sorbent to ensure maximized adsorption of cations of heavy metals and to enable production of pregnant solutions with high concentrations of heavy metals.

Dissociation of gold particles is tested in disintegration of Gurbey deposit ore samples under multiple impact effects in crusher DKD-300. It is found that in disintegration of gold-bearing schistose quartz ore, dissociation of gold particles larger than 100 μm in size extractable by gravity reaches 47%. The test results are confirmed by the data of the automated mineralogical analysis on scanning electron microscope TESCAN TIMA.

Occurrence and mineralogy of economically important rare-metal mineralization from pegmatite of Wadi El Sheih granite, Central Eastern Desert of Egypt, was previously discussed. The mineralogical investigation of the bulk composite sample collected from the studied pegmatite revealed the presence of 7.59% by mass heavy economic polymetallic minerals such as euxenite-(Y), fergusonite-(Y), allanite-(Ce), xenotime-(Y), uranothorite and zircon. This work investigated the use of high intensity magnetic separator in conjunction with gravity pre-concentration steps via shaking table concentrator to recover rare-metals and rare earth bearing mineralization of Wadi El Sheih pegmatitic granitoid sample. The results of magnetic separation are related to the magnetic susceptibility measurements of pure single crystal minerals using vibrating sample magnetometer instruments.

The flowchart is developed for gold ore flotation at the reduced impurity of the rougher flotation product with difficult middlings. The rougher flotation concentrate is subjected to scavenging by aerated air and hot steam mixture. In cold pulp slurry, the steam condensation heat is removed from bubbles to wetting films. With increasing temperature, the hydrophilic repulsive forces, that stabilize the films, can be reduced to excess osmotic pressure between the hydrophilic surfaces, and the instability of the films between the hydrophobic surfaces can be reduced to excess osmotic pressure of surrounding water, i.e. to the hydrophobic attraction forces. The test machine is designed to measure heat-transfer coefficients during aeration of water by air-steam mixture. The revealed heat loss patterns enable determining the efficient steam flow to ensure water heating in the interfacial layers of bubbles at the minimized loss of the heat source. Using an ore sample, it is demonstrated that it is possible to enhance gold recovery using the designed circuit of rougher flotation and the method of rougher concentrate scavenging.

The authors propose a mathematical model of salt particulate dynamics in a roadway, including convection and diffusion of particles with air flow, coagulation of particles, condensation of water on them, and gravity deposition of particles on the roadway floor. Using the finite difference method, the problem on flow of salt particulates in a roadway is solved, and the particulate concentrations and the average size of particles are determined. The calculations are compared with the analytical model and full-scale test data. The found correlation between the particulate deposition velocity and the aerosol parameters can be used for the parametrization of mathematical models of air-dust mixture flow in ventilation networks of potash mines.

The ground control using optical fibers is discussed. The designed monomode fiber pressure sensor is capable to perform high-precision measurement of overlying rock mass pressure imposed on walls of underground excavation. The mathematical apparatus is presented for the calculation of radiation intensity of optical wave travelling along an optical fiber with and with no mechanical effects. The simulation model is developed for an underground excavation with steal arch support. The model is equipped with the fiber-optic monitoring system and pressure sensors. This model enables practicing the ground control methods and measurements. The critical element of the simulation model is its hardware/software complex with interface showing four check zones with fiber-optic pressure sensors. This monitoring system is explosion-proof and is suitable for operation in super hazardous mines in terms of gas and dust outbursts.