Modeling and Dynamic Characteristics of a Novel High-Pressure and Large-Flow Water Hydraulic Proportional Valve

In the field of fully mechanized coal mining equipment, the hydraulic valve used in the hydraulic support is an on/off directional valve. There are many problems caused by the valve such as large pressure shock and discontinuous flow control. Therefore, a novel two-position three-way hydraulic proportional valve suitable for high-pressure and large-flow conditions is proposed to overcome the above problems. The novel valve utilizes a two-stage structure and the displacement follow-up principle is adopted between the pilot stage and the main stage to meet proportional control. In this paper, a simulation model of the novel proportional valve was established after a simplified analysis of the structural principle. Its reliability and the feasibility of the design were verified by the test results under different working conditions. Then, the step response characteristics of the proportional valve under different strokes were predicted and analyzed. Nonlinear characteristics were presented, and the closing time was shorter than the opening time because of the influence of nonlinear flow force. Under different ramp signals, the displacement of the main inlet spool was always approximately equal to the displacement of the pilot stage. Then, the motion relationship between the pilot stage and the main stage was studied, and the influence of the structural parameters on the stability was analyzed.

Application of an improved mining complex for opencast mining of ore deposits

The purpose of the study is reducing the loss of mineral raw materials and increasing the efficiency of mining operations using a mining complex through the introduction of a new design and engineering solution that improves the equipment functionality. The study involves the analysis of known designs of mining equipment capable of providing the transformation of cyclic scooping of rock mass into its continuous loading, as well as screening of fine fractions from the ore mass. High productivity mining complexes are referred to a promising direction of mining equipment development. The article proposes an improved design of the mining complex, which allows to combine the extraction and loading process and ore mass grading. The improved mining complex is equipped with an annular conveyor with vibrating grids through which fines are screened into the accumulation hopper. From the accumulation hopper the small fractions are sent by means of a pneumatic conveying system to the bunker sections of a special-purpose hauler while the oversize product is loaded into a dump truck by a dump conveyor. The fine fractions of substandard ore collected in the bunker sections are sent for heap leaching. The fine fractions of conditioned ore are sent to the concentration plant to be processed. The proposed design and engineering solution employing an improved mining complex will reduce the cost of works and increase the recovery factor of mineral raw materials in the development of complex-structured deposits of ores characterized by natural concentration of small classes. Removal of fine ore fractions directly during the excavation and loading process can significantly reduce the dusting and decrease the loss of mineral raw materials from blowing and spilling of fine fractions.

Increasing life of pit dump truck motor-wheel gearboxes by introducing the monitoring of the actual technical condition

At present, Kuzbass coal strip mines pay great attention to improving quality performance of mining equipment operation, including reliability and durability of components and units. One of the ways of the performance improvement is decreasing number of unforeseen failures. To achieve this purpose a mine dump truck part diagnostics should be introduced into a maintenance service procedure. At the same time the process of diagnostics should not increase the machinery downtime, but effectively reveal a condition of motor-wheel gearboxes in the course of dump truck operation. The aim of the research is to increase the reliability and service life of motor-wheel gearboxes of large BelAZ dump trucks. Failure of a motor-wheel gearbox is a rare phenomenon, but the cost of a new gearbox can vary from 3.5 to 10 million rubles. That is why it is important to implement such methods of diagnostics, which allow revealing the condition of gearboxes in the shortest possible time and without disassembling corresponding units. Determination of the actual technical condition of motor-wheel gearboxes is possible by different methods: vibroacoustic; acoustic; thermal; physical and chemical analysis of spent operating materials. The studies showed that none of these methods can be used as a universal one. When justifying and selecting the most suitable method, different factors should be considered, including technological, or a combination of methods should be applied, which will reduce risks, but at the same time increase costs. It is necessary to develop a better diagnostic method based on the use of several methods simultaneously.

Questions of application of fiber-optic sensors for monitoring crack growth during rock deformations

The paper considers ways to solve the problem of developing a system for monitoring displacement in quarries, which are the main main cause of the collapse of boards and berms in quarries. To ensure safety and constant monitoring during work at the quarry, there are chiseled fiber-optic sensors. The fiber-optic sensor is made on the basis of a single-mode optical fiber, which makes it possible to measure the displacements of the mountain range at distances of about 30 km with high accuracy. Laboratory sample a fiber-optic sensor in its work uses a method for monitoring additional losses that occur during mechanical action on an optical fiber. The fiber-optic sensor was made to show a fairly high linearity and accuracy during measurements and can be used to control the deformation of the array after appropriate refinement of its design. This article is aimed at creating means of controlling the process of deformation and displacement of a mountain massif. Ultimately, the results of the study will help prevent accidents associated with the collapse of the sides. Since the growth of cracks in the rocks of the bort mountain massif leads to its sudden collapse and creates a significant danger for personnel, it also causes the failure of mining equipment.

Display of cryptocurrency in accounting

The purpose of the research to determine the main features of the use of cryptocurrency and its identification as an object in the account. A comparative description of cryptocurrencies, electronic money and paper money is given. It has been established that there are no grounds to classify various types of cryptocurrencies in the accounting system as ordinary currencies or assets in a given period of time because they: are not regulated by any jurisdictions; it is not possible to identify the issuer or the specific organization responsible for its issuance; cryptocurrency exists only in the virtual Internet environment. Methods. General scientific methods and approaches, systematic approach, general research methods (analysis, synthesis, generalization, comparison), statistical methods. Results. The list of stages for reflection of activity of the business entity with use of cryptocurrency is offered and considered. The mining process is analysed and the list of cost items for the extraction of new digital coins is highlighted. The variant on reflection in the account of operations with cryptocurrency on accounts of accounting is offered. There are options for reflection in the accounting of cryptocurrency depending on its recognition: virtual goods, intangible assets, financial investments, digital money. To calculate the cost of cryptocurrency obtained by self-extraction, it is necessary to consider the main costs that need to be identified and reflected in the account. In addition to cryptocurrency, you can extract altcoins, lightcoins or convert cryptocurrencies into stablecoins, which cannot be extracted, but can only be purchased. The article presents the main aspects of calculating the cost, which include: the cost of electricity for individuals and legal entities in the country; the cost of the necessary equipment, its depreciation and maintenance, depreciation; residual value at which you can sell old mining equipment; hash – the speed of solving mathematical problems with one or another equipment; network load and production complexity; monetary value or exchange rate of a particular cryptocurrency or digital assets. Practical meaning. Despite all the scientific developments, the issue of accounting for cryptocurrency from the point of view of IFRS is quite debatable. On the one hand, most propose to account for it as a specific intangible asset. Virtual currency is a huge amount of computing power and digital assets. At this stage of technological development of mankind, cryptocurrency is gaining a stable position in the international market. Prospects for further research. Rapid development is causing further capacity growth and interest, but may eventually lead to collapse. However, if the price stability of the cryptocurrency is achieved, it can be used in international transactions, not just for speculative gain. However, this issue will be directly related to the legalization of the new currency and its recognition by central banks as a means of exchange or storage of money. There is a need for further research to understand the basic conditions for the use of digital currency in the payments market.

Performance of Passive and Active Balancing Systems of Lithium Batteries in Onerous Mine Environment

To use lithium-iron-phosphate battery packs in the supply systems of any electric mining equipment and/or machines, the required conditions of work safety must be met. This applies in particular to coal mines endangered by fire and/or explosion. To meet the spark-safety conditions, the cells (together with the battery management system—BMS) must be isolated from the influence of the environment, and therefore placed in special fire-tight housings. This significantly degrades the heat dissipation, thus affecting the operating conditions of the cell-packs. Therefore, their usage without the so-called BMS is not recommended, as shown in the authors’ preliminary research. In practice, various BMS are used, most often with the so-called passive balancing. However, their application in mines is uncertain, due to the effect of heating under operation. When it comes to active BMS, they usually possess a quite complex structure and hence, are relatively expensive. Therefore, the authors conducted research for two specially developed active and one commercial passive BMS cooperating with selected lithium-iron-phosphate (LiFePO4) batteries when used in a suspended mining vehicle type PCA-1. The tests were carried out under environmental temperatures ranging from +5 °C to +60 °C. The effect of mismatching (12.5% to 37.5% of total cells number) of the cell parameters on the temperature distribution and voltage fading at the terminals of individual cells was checked. As a result of the investigations, the practical usefulness of the developed active BMS was determined, enabling the extension of the lithium-iron-phosphate battery life under onerous mine conditions, for a single recharge, which is a novelty. On the basis of the obtained results, appropriate practical conclusions were formulated.

The impacts of the lack of ergonomic vision in mining equipment design projects on the health of workers in the maintenance sector

This study aims to analyze the impacts of the lack of ergonomic view in the projects of equipment design on workers’ health from the maintenance sector, in the mining industry context. To understand the operators’ health, maintenance activities of three types of equipment were analyzed: pump, crusher and sieve. The methodological strategy of Ergonomic Analysis of the Workplace (EWA) was used. Thus, changes in these activities are required, since some postures adopted for their performance were considered severe and with high risk. Bearing weight above the shoulders and uncomfortable positions are conditions resulted from failures in the equipment designs. To alleviate the problem, it is suggested the adoption of innovative tools or the creation of new supportive devices to improve working conditions of these maintenance professionals.

Digital technologies used in technical diagnostics, assessment of technical condition, maintenance and repair of mining machines and equipment

The article deals with the organization of a single technological space for technical diagnostics, maintenance, and repair of mining equipment. The digital technology that unites all services related to production, diagnostics of technical condition, maintenance and repair of mining equipment is based on the SAFE PLANT software package, which provides globality, scalability, versatility, integrability, modularity, distribution, and functionality. The article reflects the results of the implementation of the system at an industrial enterprise.