Home – Home – Jornals – Journal of Mining Sciences 2018 number 2

A new mechanism of deformation of enclosing rocks near mine workings is presented. The developed method to calculate geomechanical behavior of rocks takes into account the weight of overlying strata in the concordant direction with the orientation of tensile stresses at the mine working boundary while these directions differ in the mine working floor. The proposed calculation method for rock deformation includes two additional parameters characterizing the ratio of displacements in the mine working roof and floor and the ratio of the ground surface movement to to the mine working roof displacements which are determined experimentally.

Physical modeling of electromagnetic response of rock mass to low-energy impacts in terms of the Tashtagol iron ore deposit shows that multiple low-energy series of impacts initially increase the amplitudes of electromagnetic signals which later on decrease to the same level. This circumstance is indicative of the fact that the slowly varying levels of electromagnetic signals recorded after large-scale blasts are conditioned by the rock mass movement along various slip planes. The change in the stress-strain state of rocks is a slow process which takes from units to tens of hours.

The uniaxial compression testing of brittle rock specimens show that the specimens fail in the form of a columnar fracture along the axis of loading. The test data are compared with the characteristic quantities of tensile strength. Failure of the specimens is modeled with regard to features of grains, which allows assessment of tensile/compressive strength ratio.

Improvement of energy efficiency in comminution of rocks using various pretreatment methods is being explored worldwide. This paper presents experimental data on breakage characteristics of granite and sandstone using cryogenic pre-treatment. The samples were treated with varying duration of immersion in liquid nitrogen. Combined pretreatment using oven heating followed by quenching in liquid nitrogen were also explored. The results indicate that using cryogenic pretreatment uniaxial tensile strength of granite can be decreased by more than 40% while in uniaxial compressive strength about 28% reduction is possible. For sandstone as much as 33% reduction in uniaxial compressive strength was observed.

Design development of DTH air hammers is discussed with a view to increasing efficiency of rock drilling. The problem is handled by making hammering tool with curvilinear frees surfaces which are in no contact with the hammer body. This ensures generation of rock-breaking impact at the minimum energy input. New designs of hammering tools are developed for DTH air hammer models PP110EN and PP110NK designed at the Institute of Mining, SB RAS. Experiments prove that selection of rational shape of hammering tools allows improving performance of DTH air hammers by 15% at the average.

The issues connected with the prediction of mining machinery life are discussed. The basic index of reliability is an average life. The formulas are substantiated for calculating the average life of gear wheels, friction couple parts, shafts, and axles. The procedure proposed to calculate the life standard deviation is based on the method of linearization of functions of random variables. In this way, the life of standard parts of mining equipment can be calculated as random values with regard to operation conditions. Application of the procedure is exemplified by calculations of the life of a roller bearing. The calculation results are confirmed in the numerical experiment by the Monte Carlo method.

The results of the research aimed to substantiate parameters of loose ore and rock mass (protective cushion) formed to protect and isolate underground excavations from the open pit mine at Udachnaya kimberlite pipe under mining with the caving methods are presented. The thickness of the cushion is determined based on the effect of an impact of caved rocks and the resultant air blast, and is meant to isolate aerodynamically and thermally the open pit and underground mines. The thickness of the protective cushion is calculated with regard to an increase in the depth of mining down to a level of -680 m.

The problem connected with the mine support with metal frames in unstable rock mass subjected to stoping is analyzed. In terms of the complicated geological conditions of the Orlov Mine (East Kazakhstan), the application of phenol resin Blok-Fil in filling voids and domes after rock falls in the gap between the metal frames and roof is tested at the laboratory and pilot scale. It is found that owing to complete filling of voids with resin, no dynamic loads on the support due to rock falls and self-heating of ore and mine air are observed.

The experimental research findings on processes that take place during differently directed controlled trajectory blasting of ore and gangue in underground mining of flat-dipping veins are presented. It is found that methods for designing blast patterns should take into account both linear concentration of energy and dynamics of the increase in resistance to throw of rocks and ore in a narrow stoping area. Based on the modeling data, the throw coefficient and blasting front advance are plotted as functions of geometrical and energy characteristics of the model. It is shown that blasting and throw of ore in the stoping zone is accompanied with the effect of additional fragmentation of ore due to collision with the stope roof.

Deep sea mining was identified in the middle of last century. However, its industrialization and commercialization today are limited in the costal mining industry due to the high mining cost and technical issues. The purpose of this paper is to analyse a green transport plan of deep sea mining systems in terms of the optimal efficiency of the rigid pipe lifting system and the total energy consumption. The deep sea mining facilities considered in this paper consist of a mineral collecting machine, a flexible hose, a rigid pipe, a grinding machine, a concentrating machine and a horizontal pipe conveyor. Centrifugal pump modelling and its working principle are researched, because it is the major transport facility. The relationship between the optimal efficiency, total energy consumption, transport loss factor, and the relating mining parameters is determined by numerical simulations and fittings under Fortran and Matlab environment, and the optimization under 1stOpt environment. The research conducted in this paper is valuable for the pre-evaluation of deep sea mining transport systems and the further realization of its industrialization and commercialization process.

This study discusses the prediction of penetration rate and specific energy of button bit equipped rotary-percussion drilling machines from drill cuttings and geo-mechanical properties of rocks. The operational parameters of drilling machines measured from selected locations were utilized for the calculation of specific energy of drilling operations. For this purpose three on-going hydropower projects and four active mining quarries of Pakistan were selected. The drill cuttings were further used to determine various descriptors of the chip size distribution including the coarseness index and Rosin-Rammler’s absolute size constant. A complete set of geo-mechanical rock tests were conducted in the laboratory and includes uniaxial compressive strength, Brazilian tensile strength, point load strength, Schmidt rebound hardness, p-wave velocity, dry density, porosity and brittleness indices. Regression analyses were performed to predict the penetration rate and specific energy of drilling from geo-mechanical properties of rocks. The models so developed were also validated by adopting the t-test and the F-test statistical techniques. Moreover, statistical models were also developed to evaluate penetration rate from various descriptors of the chip size distribution. Dependence of bit size on coarseness index and mean particle size was also discussed.

The investigation of influence exerted by ultrasound exposure on recovery of zirconium and rare earth elements in pregnant solution of acid leaching of eudialyte concentrate is described. The methods of X-ray photoelectron spectroscopy and analytical scanning electron microscopy are used to study structural, chemical and morphological characteristics as well as elemental composition of minerals in eudialyte concentrate before and after the acid leaching.

The mathematical model of treatment of mineralized mine wastewater by pressure flotation is described. The model provides information on concentration of metal substrates in each state of the process at any arbitrary time. The numerical experiments based on the model prove its reliability and accuracy.

The results of the thermodynamic modeling are presented for oxidizing roasting of refractory molybdenite (MoS₂) with magnesite (MgCO₃). The phase and chemical compositions of the MoS₂-MgCO₃-O₂ system and its changes are determined depending on the temperature and quantity of the additive agent. The modeling reveals feasibility of thermochemical decomposition of molybdenite with the formation of water- and soda-soluble compounds MgMoO₄ and MgSO₄, which is an evidence of efficiency of magnesium carbonate in the capacity of an additive agent. The optimal conditions of the thermochemical decomposition of molybdenite determined theoretically from thermodynamic calculations are proved experimentally.

The processes of physicochemical treatment of nepheline concentrates are studied theoretically and experimentally, and the optimal conditions are determined for the integrated fluoride-ammonium recovery of different useful components. The enabling innovative technology is proposed for the production of amorphous silica, alumina, red iron oxide, calcium fluoride and other marketable products.

Applicability of local and regional scale satellite images in evaluation of vegetation in tundra in the zones of mining in permafrost area is proved. The research findings on the environmental impact of the Valkumei Mine, Chukotka Autonomous Okrug, after its closure are described and analyzed.

The spotlight is on the use of Earth remote sensing data in geoecological assessment of the Malyi Khingan Ridge area in the Russian Far East. Based on the analysis of satellite observations over the Sutara gold placer mining range, the time variation of the disturbed land is determined. It is found that natural recovery of bio-geo-cenosis takes an active part in the process. Using the normalized difference vegetation index (NDVI), the behavior and rates of self-healing of the disturbed lands are assessed. Complete recovery of vegetation in gold placer mining areas up to a level comparable with the adjacent territories takes 7 to 10 years.

The methods of deactivation and reclamation of tailings ponds are studied. The engineering-geological investigations of apatite-nepheline ore flotation tailings in the sites applied with chemicals at ANOF2 processing plant of Apatit Company are carried out. The monitoring of the bonding surface generated by dust suppression agents Alcotact DSI, Dustbind and Dloset S44 is performed. The physical properties and the aggressive action resistance, as well as the effect of suppression agent feed in recycling water on the apatite-nepheline ore flotation performance are tested on a laboratory scale. The Dustbind is recommended as the optimal suppression.

Stationary-state combustion of fine dispersed dust-gas-air mixtures in underground excavations is analyzed. Under the assumption that the single source of heat emission is the carbon oxidation reaction, the second-order nonlinear differential equation is obtained for the determination of temperature and the initial conditions are formulated. The analysis of the solution shows that there exist critical values of the dust-gas-air mixture flow velocity, and the excess over these critical values may result in the mixture combustion. The cross section of an underground excavation is related with the temperature reached in this cross section.

The structure diagram and operation of a hybrid unit for drilling and initiating slotting are presented. The loads on the cutting tool during initiating slotting are calculated, and the rational operating mode of the hybrid unit is determined.

The variant of the gamma albedo method is proposed for the radioisotope express control of coal ash content, which ensures the satisfactory accuracy in the conditions of variable elementary composition of coal. It is shown that the integral intensity of secondary (scattered and fluorescent) radiation weakened using a certain thickness filter is a univocal index of coal ash content. The analytical model for the optimization of the secondary radiation filtration parameters is developed. The utility value of the weakening filter is determined as function of ash content and composition of coal.