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Abstract

The paper presents a new method of determining the energy consumption for vibratory crushing. Using the laboratory vibratory jaw crusher with kinematic actuation of the jaws, the study of determining power consumption while crushing limestone and diabase was conducted. During the study, electrical energy used on the crushing process was measured as a function of changing design and kinematic parameters of the vibratory crusher, i.e.: jaws stroke, the outlet gap size and frequency of jaws vibration. The article presents program of the research, the laboratory test stand of the vibratory jaw crusher KW 40/1 and the test results. Comparing the theoretical crushing energy requirements, determined by the Bond hypothesis, with the values measured during tests a large differences were observed. Using the Bond hypothesis the Vibratory Work Indexes were determined for the tested materials. Their values are higher than limestone and diabase Work Indexes available in the known literatures. The explanation may be greater amount of energy transferred to the material during vibratory crushing, which results in much higher efficiency of the crushing process.

Abstract

Conical picks are cutting tools used in many branches, in particular in the mining, road construction and building branch. Contact with the excavated face causes their constant wear, which is an unfavorable but unavoidable process. Milling heads of working machines are equipped with several dozen conical picks, and mining in abrasive or hardly accessible rocks can reduce their life to a few hours. It is in the interest of both users and producers to increase their durability, as tools replacement, apart from purchase and logistic costs, results in machine downtimes. In the article various solutions of conical picks, their construction, dimensions and materials used have been discussed. Technical procedures applied to increase the durability of conical picks and their regeneration as well as methods of extending the life of picks working in difficult conditions have been presented. Two author’s methods of extending the life of picks working in difficult conditions, covered by a patent application, have also been presented. The first solution involves ensuring an uninterrupted rotational movement of the pick in the holder. Patent claims include an innovative method of equipping the additional sleeve integrated with the holder with a rotational bearing, which enables a continuous rotation of the pick. The tool equipped with a bearing generates much lower movement resistance than the standard mounting. The holder is designed to mount classic commercial picks. What is important, the pick replacement does not require interfering with the bearing assembly. The second solution concerns the manner of protecting the working part of the pick by means of a special element made of an abrasion resisting material. This element is the pick tip, the geometry of which varies from the commonly applied posts made of sintered carbide. In this solution, the tip has a shape corresponding to the form of conical pick’s wear, which causes that its steel body does not wear. Moreover, there is a possibility of applying a mobile, rotational mounting of the tip to the body.

Abstract

The article presents the assumptions and main functionalities of two operator support systems – the FGS (Feeder Guiding System) and the remote control system of a drilling or bolting rig. Both of these systems greatly facilitate the work of an operator of a self-propelled mining vehicle in the conditions of an underground metal ore mine. The first of the described system allows for real-time control of the current position of the mining boom and facilitates the drilling of blast holes according to a predetermined drilling pattern. The second of the systems – a remote control system – is used especially in conditions of unstable rock mass or in the case of work in particularly difficult operating conditions, where it is advisable to limit the presence of the crew from the face-up to the necessary minimum. The intensity of these vibrations was related to the conditions of the cutting process.

Abstract

The article presents methodology and selected results of simulation tests of diesel and electric dive system for drilling rig. Research in this field were conducted under the project no. POIR.01.01.01-00-D011/16 entitled „New generation of modular rigs, drilling and bolting, with battery drives, designated to work in underground cooper ore and raw rock material mines”. The project is funded by the National Center of Research and Development (NCBiR). The aim of the project is to design and implementation of innovation drilling and bolting rig with electric drive system. Due to the complexity of the structure of the drive system (mechanical, hydraulic and electrical elements), it was necessary to use advanced simulation software dedicated to multiphysics analysis. Data presented in the article can be used as guidelines in design process of drilling and bolting rigs as well as in optimization their driving system and mechanical construction.

Abstract

Underground salt mining accounts for about 16 percent of the total salt production worldwide. When excavating salt rock, the cutters of the road header come into contact with the rock. This produces friction and, consequently, a rise in temperature. Generally, as temperature increases, salt gradually loses its plasticity. The extent of these alterations depends on the presence of other minerals in the rock. This paper presents the results of laboratory tests on regularly shaped samples of salt. An analysis was performed of the results of compressive, tensile and induced-shear strength, and of Young's modulus, Poisson's ratio, cuttability index and side chipping angle. The testing was conducted on samples with a temperature of about 20°C and samples heated to 50°C and 80°C. The tests showed that as temperature increased, so did compressive and tensile strength, and longitudinal and transverse strain of salt. The temperature increase caused, however, a decrease in shear strength. The cuttability index and the side chipping angle also decreased when the heated samples were being cut. The percentage changes in the parameters within the 60-degree temperature range were as high as several dozen percent.

Abstract

Insight of man-machine interfaces during mining machine operations, better co-ordinance with human efficiencies and suitable workload selection in underground mining machine operation are the main viewpoints of the study. Total 12 side discharge loader (SDL) and load haul dumper (LHD) operators [N = 12] have been taken as participants of the study. The methodology is divided into two parts first part is devoted to measuring and analyzing workload response of machine operation with polar heart rate monitor. Machine operator’s heart rate ratio (HR ratio) for the whole shift is recorded and metabolic rate (MR) has been analyzed. Additionally, fatigue sustainability (FS) and degradation of muscle force (MF) are recorded for each work cycles up to exposure time period (ETP) of 360 minutes. In the second part of the methodology, based on the HR ratio recorded during the mining operation, a workload simulation study is undertaken on a treadmill at the surface following BRUCE protocol. At treadmill, based on HR ratio, workload achieved from mines along with three different workloads i.e. low, moderate and high has been tested. Differences in FS and degradation rate of MF after each workload experiment have been recorded. A result from the underground operational study shows that there is about 43.2% and 32.4% of decreasing MF for SDL and LHD operators after end of spells at mines. Additionally, a negative correlation (r = −0.99) is found between ETP and MF. The workload simulation study shows that there are significant differences between FS (p < 0.05) and MF (p < 0.05) data of mining and treadmill experiment with the same workload. In comparison to an underground operation, FS rate of low, moderate and high workload is recorded 60%, 35%, and 15% higher respectively than of mine workload. Higher FS rate may achieve due to availability of good environment. Among the tested workload only low kind of workload is found suitable for mining machinery job as degradation of MF is found significantly (p < 0.05) low and FS is found significantly (p < 0.01) high in this kind of workload. Therefore, it can be concluded that in mining machinery operation better to adopt low workload for effective utilization of man shift (EUMS) as it gives comparatively low MF degradation and better FS during continuous work.

Abstract

The main task of the maintenance services in hard coal mines is to ensure continuous operation of the equipment (machines). The measurable effect of these actions should be the reduction of maintenance costs of equipment (machinery) and thus the reduction of production costs – coal mining. The paper presents an issue of failure rate of technical measures applied in the mining process. In order to ensure greater efficiency and productivity, it is necessary to find the causes of the most frequent failures in this process and effectively counteract them. As a result of these activities, the production availability of machines/equipment involved in the mining process will increase. This will to a large extent ensure failure-free and uninterrupted progress, increase productivity and improve the quality of manufactured products, as well as reduce the operating costs of equipment (machines), and thus reduce production and product costs. This effect should consist mainly in the control of rational, safe and effective use and operation of equipment (machines) in the exploitation process. An algorithm implemented in one of the hard coal mines was presented. The technical condition of underground mining equipment was observed by periodical measurements of vibration parameters at selected points on the machine – measurements were conducted with a vibration pen. The aim of this research is to improve the reliability of technological process of a mining plant through its failure-free operation. In order to achieve this objective, i.e. the efficiency of a mining company, it is necessary to reduce its costs. The action that leads to this aim is a proper assessment of the technical condition with regard to the equipment used in technological process.

Abstract

Very fine crushing of hard and very hard materials, to product of particle size less than 2-4 mm at feed particle size of 50-200 mm, requires a very large energy inputs. This is mainly because of the need for at least three or even four degrees of crushing, containing: jaw, cone or impact crushers. One of the methods of reducing the amount of energy expended on the crushing process is reducing the number of crushers in technological line. By replacing a large number of less effective crushers with fewer machines but characterized by higher crushing efficiency we can gain considerable savings in investment and operating costs. This is possible by using crushers capable of obtaining much greater degrees of fragmentation than the aforementioned, that is vibratory crushers. The paper includes the systematic of currently used vibratory crushers, their mechanical diagrams, descriptions of the construction and operation, and basic technical parameters as well as examples of crushing technological lines utilizing vibratory crushers.

Abstract

The analysis of the state of security in the coal mines of Ukraine showed an urgent need for equipment to monitor the safety of production processes, identifying its shortcomings. The necessary regulatory requirements of the legislation of Ukraine on this issue have been considered in detail. A solution to the problem of creating modern equipment for monitoring the safety of production processes in coal mines through a new approach and a change in concept has been proposed.

Abstract

This article attempts to solve the problem of load compensation in mesh planetary gearing, with the innovative design idea, resulting from the increased plasticity of the planet wheels (satellite). The cognitive main objective of the experimental work was carried out to identify the comparative effect of the split narrow planet gears, on the load distribution on the length of the teeth of the planet gears of the central wheel of the planetary gear. Achieving this aim, in addition to in-depth analysis, requires experimental research on a specially-built test stand and simulation tests on a solid model of the transmission using the finite element method (FEA). This article presents the concept of a novel test stand, design methodology and research on the influence of the sectional satellite wheels on the load mesh of planetary gears in mining machines.