The present work considers the problems of mining lost ore reserves out of protection pillars, which were unprofitable to develop before. At present time due to the deterioration of mining and geological conditions, it is sometimes economically reasonable to return to the previously mined sections and develop the pillars at the upper horizons which were preserved under the exploitation. These pillars usually have over 25% of balance reserves of metallic ore, up to 60–70% of potassium salts and more than 30% of coal. The technology of mining these pillars plays important role under the assessment of the possibility of their excavation, because the protection pillar, as a rule, represents highly fissured and tectonically disturbed ore massif. When mining protection pillars two situations are possible: in the first one – strength characteristics of ore body are significantly higher than strength and stability of enclosing rock; in the second one – strength characteristics of enclosing rock are significantly higher than the characteristics of ore massif. Taking into account all stated by the authors, it is suggested to fulfill the excavation of reserves out of protective pillars with chamber systems of development with preliminary strengthening of enclosing rock in the first situation, and in the second situation – perform it under the protection of concrete support created in ore body in the shape of volumetric grating. The suggested technology has been tested at Berezovsky deposit and Zyryanovsky lead plant. The results of the investigations permit to recommend the technology developed by the authors to be used at other enterprises with similar mining and geological conditions.
The article is devoted to the problem of reducing the dilution of metal ore by overlapping and enclosing rock in the production process in underground mining. Some information is given about the state of knowledge of production quality management processes under the development systems with a collapse of ore under the overlapping rocks. Development results are introduced of a complex field structure under a flexible tree-rope and steel cable overlappings. The practice in the application of overlappings of different structures depending on the conditions of development in the uranium-mining industry is described. Overlappings strength determination methods are systematized and typified. For the conditions of polymetallic deposit, economic-mathematical comparison of alternatives with the collapse of the core technology and under the overlapping is fulfilled. The problem of improving the quality indicators of the produced ore are formulated through the separation of ore and rock by the overlappings, including the substantiation of the separation efficiency, optimization of overlappings design for each type differentially, the release of lost ore under the overlappings effectiveness determination, and overlappings structure development. The article systematizes the engineering methods of reducing dilution magnitude with the release of the previously lost ore which are applied in ore mining, also by means of load-bearing and separating overlappings application. It is predicted that the prospects of the direction include bridges cost-cutting through the development of new composite materials. It is shown that improving the quality of previously lost produced ore and ore extracted with overlappings is an essential element of expanding raw-mineral base and mining enterprises economic rehabilitation. The results of the study are of interest to some existing mining enterprises and some mining enterprises under construction.
The article describes the investigation directed to determine strength characteristics of loamy rock of placer gold field “Kliuchi”. In the course of work with the use of the common method of ultimate shear strength, bond index and internal friction index have been determined. With the calculation method, tensile strength in uniaxial compression has been determined. Simultaneously, the calculation of fineness ratio and plasticity index were carried out, the indices of which were used to determine bond and internal friction index with “Dal’NIIS” method. At the same time, with the account of thorough preparation of models, experiments over the determination of tensile strength of loamy rock in uniaxial compression have been carried out. Comparative analysis of the enumerated methods over the determination of strength characteristics has shown insignificant divergence in the acquired data.
Imitation modeling program algorithm is in the basis of foundation ditch fencing wall anchor support construction calculation; the program fulfills quantitative estimation of reliability and risk of underground facilities construction. The main estimation method is simulation testing according to Monte Carlo method, which is realized in the mode of automated application program and test files in QBasic programming language. On this basis, machine oriented procedure of flexible retaining constructions design has been worked out, which helps to make efficient probability analysis of loads upon the bearing construction, sliding surface locations and anchor supporting nodes stability. Risk degree determination when designing stable flexible retaining constructions of foundation ditches for urban underground constructions which are built with opencast mining method is extremely topical issue. Evident way of the said problem solution is formalization of risk-analysis, which includes the development of geotechnical situation modeling method by average values of input data.
The article examines the problems of sustainable land use in industrial regions; system of notions about land in the sphere of sustainable land use is introduced. The methodology of sustainable land use is examined on the basis of maintaining required level of biotic environmental control, hierarchy of control levels of sustainable land use (conceptual, ideological, political, and economic) and scientific-technological principles of sustainable land use in industrial regions. The principles include the substantiation of strategic priorities and indicators of sustainable land use in industrial regions; complex (ecological-economic) estimation of land resources with the account of industrial production peculiarities; determination of “corridors” of allowable land use in industrial regions; co-ordination of individual interests of land users with social preferences; multicriterion optimization of land use on the basis of ecological-economic and social indicators. The examined interdisciplinary approach with the use of strict mathematical formalization of social-ecological-economic processes in the sphere of land use will help to take into account modern challenges, reduce risks, and mitigate the consequences of negative situations.
A new way of dust suppression in open pits is suggested, based on water pulverization from pressure pipelines of water drainage facilities. The elements of the dust suppression system have been examined, which are located along open pit automobile roads. The article introduces the methods of detecting pressure characteristic of water drainage facility with track water intake for dust prevention. Calculation of possible parameters of water drainage combined with the suggested moistening system operation is fulfilled. On the basis of the obtained performance figures some recommendations on the pumps selection are stated for open pit water drainage facilities with track consumption water flow rate in the areas of roads moistening; conditions of these facilities rational use are also justified. It is shown, that capacity overstock of a pump station under normal water inflows piping out to the open pit is an important factor for water drainage facilities effective use to reduce air dust content.
Within the real conditions of blasting operations the content of explosion products is diverse and differs significantly from the ideal conditions. Detonation products are chemically more active than aerial oxygen, and they can work with the rock, coal in particular, which is in active condition. At that, coal combustion possibility rises. The presence of the products of partial oxidation of combustible additives and trinitrotoluene, which also possess higher chemical activity, also leads to the similar result. Investigation and observation results in various periods of coal deposits development in Mongolia show that fires more frequently develop in blocks of coal bench in the rock mass, which has been mined with drilling and blasting operations. Under rock loosening with a blast, the time of incubation period of coal masses to combustion is shorter as compared to mining without using drilling and blasting operations. The transfer to the use of granulated coarsely dispersed explosives at the opencast coal mines of Mongolia has led to the development of unbalanced according to the oxygen balance system and the emission of a great deal of nitrogen oxides at the time of the explosion. The wide use of mixtures of ANFO type in the period of 2005 to 2015 has led to massive cases of spontaneous coal combustion and technogenic fires, which therefore has led to a higher risk of coal deposits exploitation. Investigations fulfilled by the authors allowed creating for Mongolia conditions special technology of producing and using ammonium nitrate explosives, which possess balanced composition and evolve minimum quantity of poisonous products during the explosion, which cause accelerated spontaneous coal combustion. The use of the developed technology of ANFO mixtures production almost eliminates spontaneous coal combustion after the explosion.
New approach to geomechanical analysis of mining units is implemented by a specialized software package of nonparametric statistics methods. The complex provides quality improvement of source data about the condition of enclosing rocks and properties of rocks according to the data from minor mine workings. The article examines four directions: statistical estimation of rock properties; peculiarities of parameters determination of certificates of rock strength with nonparametric estimation according to the results of field tests at drilling wells; engineering-geological mapping of rock mass; geomechanical models construction on basis of nonparametric statistics methods. The resources of nonparametric statistics are used in simulation models transforming the distribution of input parameters with random number generation from 104 to 106.
The article examines the possibility to use of pipeline pneumatic transportation system to transport cargos and passengers at a section “megapolis–industrial enterprise”; the scheme of which is developed at the Ural State Mining University (USMU) together with a group of companies “Transprogress” and Ural State Academy of Architecture and Arts (USAAA). The article offers patented methods of continuous railway operation of passenger pneumatic transport at station pipeline sections with specific systems development, including transparent pipeline main lines. A scheme of bulk goods delivery is revealed, with the use of a set of equipment of continuous operation transportation systems. Its advantages are shown; comparative analysis is fulfilled of automobile, railway and conveyor transport. Maximum exploitation parameters are determined for drive tyres to transfer draught power for containers (pneumatic trains).
All stages of technological process at modern ore mining open-pits are accompanied by intensive dusting. Dust suppression depends mainly on physic-mechanical properties of rock, atmospheric phenomena, speed, mass and type of open-pit automobile transport. With wide application of automobile transport at open-pits, road without solid surface are intensive sources of dust suppression. High dust content in the air at an open-pit abruptly reduces automobile transport speed of movement, causes increased wear of engines and raises accident rate. People long term stay at dusty atmosphere can cause occupational lung diseases. In Russia dust binding materials for dust are scarcely manufactured, these materials are aimed to remove dust from automobile roads at open-pits. Preventive emulsions from black oil of oil refineries are examined; adhesive characteristics of their resins and asphaltine components are estimated in laboratory conditions. Industrial appraisal of dust removal at approach and opencast automobile roads of Volkovsky mine is carried out in 2015. Technical and economic indices of actions for dust removal are determined.