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Gornye nauki i tekhnologii = Mining Science and Technology (Russia)

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Vol 5, No 3 (2020)
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BENEFICIATION AND PROCESSING OF NATURAL AND TECHNOGENIC RAW MATERIALS 

188-200 738
Abstract

A promising line in development of reagent consumption automatic control systems is applying data on measuring collector concentration in the pulp aqueous phase. For effective using data on the concentration of the nonionic collector – allyl ester of amylxanthogenic acid – in the process of flotation, the studies were carried out and the method for analyzing its residual concentration in the flotation pulp liquid phase was developed. The developed spectral technique for measuring the concentration of amylxanthogenic acid allyl ester in the pulp aqueous phase showed stable results in the temperature range of 10 to 25 °С, pH range of 8.5 to 11.0. This allowed applying the technique to measuring residual concentration of AeroMX- 5140 collector in the operation of bulk sulphide flotation in copper-molybdenum ore beneficiation. The laboratory tests allowed determining connection between the indicators of residual concentration with the main indicators of copper-molybdenum flotation. The studies showed that increasing the residual concentration of the non-ionic collector occurs with increasing its consumption and pH of the pulp aqueous phase. It is shown that significant increase in metal recoveries is observed at similar residual collector concentrations: for copper, in the range of 0.25 to 0.5 mg/l, and for molybdenum and pyrite iron, at the concentrations from 0.25 to 1 mg/l. The possibility of using the nonionic collector residual concentration as the informational indicator of the flotation process has been substantiated. It is proposed to use the ore absorption capacity in relation to the collector applied as an indicator of the ore grade. It is shown that using this indicator reduces relative variance for the dependences of the yields of individual ore types and increases the accuracy of determining the composition of the processed ore as a mixture of typical ore grades. An algorithm for automated control of the consumption of flotation reagents based on the advanced control of the processed ore elemental and mineral composition was developed and tested at Erdenet GOK processing plant, with the calculation of the pulp absorption capacity in relation to the nonionic collector, including the beneficiation process indicators determination using an economically-oriented optimization criterion. The expected economic effect from the reduction of metal losses amounted to USD 145 thous.

MINING MACHINERY, TRANSPORT, AND MECHANICAL ENGINEERING 

201-207 672
Abstract

Hydraulic power cylinders are the main bearing elements of powered supports at mining enterprises, ensuring reliable fixation of the roof in the required working position, as well as providing advancement of the support in the face. Thus, hydraulic power cylinders ensure stoping safety, so strict requirements are im-posed on them both in terms of workmanship and operational reliability. To ensure reliability and efficiency of powered support operation in faces, it is necessary to ensure stable service life of their hydraulic props, which mainly depends on the quality of manufacturing of mating surfaces and the accuracy of assembling functional joints. The required accuracy of hydraulic prop joints is achieved by selective assembly, which allows ensuring the specified technical requirements and service life of the joints. At the same time, along with the issues of ensuring the accuracy of assembling the props to provide proper safety of the face operation, it is extremely important to identify and analyze the causes of dimensional wear of critical parts of the joints, leading to decreasing service life of the hydraulic props in the course of exploitation. In the paper, using the methods of the analytical theory of bases, the reasons for formation of positional variations of the parts of the powered support hydraulic prop joints in the course of assembling and operation of the unit are identified and described. It was found that arising mismatches and formation of local stress zones on the cylinders, pistons and rods, characterized by intense wear, occurs due to the uncertainty of basing (positioning) of rod and piston in hydraulic cylinder. The dependencies allowing calculating deviation of the rod axis from the required position, taking into account the initial clearance gap in the joints and the adopted design parameters of the hydraulic cylinder, have been obtained.

SAFETY IN MINING AND PROCESSING INDUSTRY AND ENVIRONMENTAL PROTECTION 

208-223 811
Abstract

The subject of research was technogenic waste systems formed in the last century due to the activities
of presently closed mining enterprises in the Amur River Region and Primorye of the Far Eastern Federal District of the Russian Federation. Experimental studies allowed to establish that toxic sulphidized mineral processing waste accumulated for the 20th century in tailings storage facilities (TSF) in large quantities produce negative impact on the environment. It was revealed that their conservation and reclamation were not carried out. However, they pose huge threat not only to the environment, but also to public health. In this regard, the research goal was to assess environmental hazard of the accumulated toxic waste and substantiate the possibility of mitigating their negative impact on biosphere components and human health. Based on the research goal, the following tasks were set: 1) analysis and generalization of the existing experience of studying the problem in Russia and abroad; 2) identification of the main sources of crisis situations at closed mining enterprises, indicators and criteria for as sessing the environmental hazard of the accumulated mineral processing waste; 3) assessment of the environmental hazard of the accumulated mineral processing waste; 4) development of principles and measures aimed at ensuring environmental safety of TSF comprising toxic waste. The following methods were used: physical-chemical, bio logical, as well as mathematical modeling, GIS technologies, etc.Based on the study of the TSF current state, assessment of the level of technogenic environment pollution, and patent search, the authors substantiate the need for effective solution to this problem. It was found that the waste belongs to the second hazard class (highly hazardous). The excess of 4 to 46 times above the regional background indicators (metal concentrations), and more than 200 times above MPC was revealed. It has been proven that the TSF surface does not naturally run wild for 30 years. Patent search and our own experimental research allowed developing measures to ensure environmental safety of sulfidized tin ore processing waste, novelty of which was confirmed by patents of the Russian Federation.

GEOLOGY OF MINERAL DEPOSITS 

224-234 726
Abstract

Peat deposits accumulate large reserves of carbon and play an important role in formation of global
climate, biosphere, and hydrological conditions. High degree of knowledge of peat reserves is one of the prerequisites for scientifically based and economically viable wetland management. For economically efficient commercial activity, an enterprise developing a peat deposit must be confident in the availability of sufficient and high quality commercial peat reserves. Therefore, the topic of studying the thickness of peat deposits is quite relevant. The paper analyzes the experience of using the geophysical method called VLF ("very low frequency") to study the thickness of peat deposits. The method consisted of using a VLF receiver to measure the properties of VLF emitted by the peat deposit and the underlying mineral ground. The study was carried out at the Beloe Lake peat deposit in the Tukayevsky district of Tatarstan, at three peat areas of different depths: deep-lying (over 3 m), intermediate (1.5 – 3 m), and shallow (up to 1.5 m). The depth was confirmed by direct measurements in the wells. Low-frequency (VLF) measurements were carried out along the geophysical paths at each area of the peat deposit. The data were processed using the NAMEMD (Noise Empirical Decomposition) method and converted to resistivity and depth values using the specialized software. The study showed that the resistivity differs significantly between the areas of deep-lying and shallow peat. The resistivity varies depending on the peat thickness and the thickness of the buried wood horizons. In the horizons of deep-lying peat, the resistivity is strongly influenced by the degree of peat decomposition, its natural density and moisture. The presence of peaks and their height on the data interpretation plots characterizes the number and thickness of the horizons of buried wood in the peat deposit. With increasing depth of peat occurrence, the resistivity increases significantly. However, in the shallow areas, it does not show differences, being characteristic for the deep-lying peat area. This proves that the VLF method works correctly in peat layers and is capable to indicate the peat thickness, the number and thickness of the buried wood horizons.

MINERAL RESOURCES EXPLOITATION 

235-252 391
Abstract

Involvement of deep deposits in mining predetermined the trend of development of open pit mining towards increasing the depth of open pits. The main limitation imposed on drilling and blasting in the near-contour zone of an open pit is the need to protect the pit walls and engineering structures on the walls from seismic effects of huge blasts. As practice shows, the most effective and proven method of protecting pit walls is the use of blasting by presplitting method, creation of a shielding gap and a shielding layer of blasted rock mass, i.e. pre-splitting of the pit walls, preceding the huge blast. Therefore, the study of stress-strain state of the near-contour rock mass, determination of the parameters of blastholes for edge pre-splitting (preliminary shielding gap formation) in open pits is an urgent task. The analysis of the pit wall design and stress-strain state of rock mass at Kokpatas deposit exploited by Navoi Mining and Metallurgical Combine allowed to determine the model, as well as the method for calculating stress-strain state of the rock mass. When assessing stability of the pit walls, an approach known as the displacement method was used. Applying the boundary integral equations method allowed to develop an algorithm for calculating stresses in the rock mass for the conditions of Kokpatas deposit. A technique has been developed for experimental studies of blasting contour blasthole charges (blasting by pre-splitting method) using models, allowing to study fracturing on volumetric models and wave interaction by the method of high-speed video recording of the blasting process in transparent models, as well as to determine the parameters of stress waves during blasting in samples of real rocks. A method for formation of stable pit wall slopes, an excavator method for bench pre-splitting on ultimate envelope (contour) of a pit, and a method for initiating blasthole charges in the near contour zone of a pit have been developed and implemented in the industry.

POWER ENGINEERING, AUTOMATION, AND ENERGY PERFORMANCE 

253-265 280
Abstract

Many heavy machines and mechanisms of mining and metallurgical industry, for example, basic-oxygen converters (BOCs), are equipped with multi-motor electric drive. Reducing the influence of the disadvantages characteristic of a branched multi-connected system is possible by creating control systems based on mathematical models of the considered electromechanical systems (EMS). The full mathematical model takes into account the number of EMS motors, gear backlashes, elasticity of shafting, the effect of dissipative forces, etc. Disadvantage of this approach is complexity of such models, which leads to high computational costs and time expenditure for their implementation. To analyze dynamic processes arising under acceleration and deceleration conditions of the electromechanical system of the converter tilting mechanism, it is proposed to use a simplified equivalent simulation model, which would take into account changing the EMS natural oscillation frequency for any operation conditions based on process and design features. Based on the simulation model analysis, it was concluded that it is necessary to assess mechanical loads in the system by comparing their current and basis values, as well as taking into account the damping properties of the electric drive. To reduce dynamic loads, it is proposed to form a law of changing the control voltage using an intensity generator, which reduces the risks of occurrence of elastic moments, significantly exceeding those permissible for this class of mechanisms. The results of thermal and vibration diagnostics for assessing malfunctions of key units of the converter tilting mechanism, as well as assessing the system behavior based on the Matlab Simulink model with varying shafting elasticity and normalized gear backlashes, showed significant effect of the latters on the dynamic loads.

EXPERIENCE OF MINING PROJECT IMPLEMENTATION 

266-284 377
Abstract

A geological exploration company is a modern enterprise, possessing advanced techniques and carrying out full range of high quality exploration for all types of solid minerals in accordance with world standards, which is the center of competence in uranium geology, as well as provides its services in the field of exploration for solid minerals. To date, the tasks of ensuring replenishment of explored mineral reserves, increasing efficiency of their use, as well as increasing profitability and capitalization of enterprises of mining-and-processing industry remains relevant. To implement a set of measures for solving problems associated with prospecting, exploration, and exploitation of uranium deposits, it is urgently required to develop the following improved approaches and methods: modernization and re-equipment of methodological and technical base of the enterprise’s chemical analytical laboratory for implementation mineralogical and radioisotope methods of prospecting for uranium deposits; carrying out work to expand the scope of accreditation, environmental research, and training of specialists for field laboratories; creation of an information system for geological data bank, which allows organizing a single information space and ensuring availability of the necessary reliable data, as well as their safety/integrity and the data access control. The conducted research formed the basis for the development of mechanisms for achieving strategic targets and implementing strategic objectives of the enterprise. To ensure sustainable growth of key performance indicators of the enterprise, it is necessary to focus on long-term successful work. This is connected with restructuring of assets and diversification of the company's activities, development of innovative methods and facilities for prospecting and laboratory-and-technological research, improvement of the set of radioecological studies at exploration areas, and introduction of the principles of corporate and legal culture. Providing growing demands of affiliated mining enterprises for mineable resources by replenishing the uranium resource base should be based on active prospecting, exploration, and discovery of new uranium deposits, as well as formation of highly efficient professional personnel. To improve management efficiency, the enterprise should activate and improve the quality of exploration, as well as diversify the company's activities and reduce possible risks. Implementation of this approach is possible through the formation of highly efficient professional personnel based on the recognition of high economic value of human resources. In addition, it is necessary to actively conduct exploration in promising areas for discovering new deposits and, correspondingly, increasing and replenishing the company's uranium reserves and increasing its assets. This will allow prolonging the life of the company’s mines until 2040 due to increasing additional explored reserves.



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ISSN 2500-0632 (Online)