Łukasz Bołoz

Mechanical rock cutting is widely employed in both the mining and construction industries. One of commonly used techniques is cutting with conical picks, which can process various rock types, including hard-workable and abrasive rocks. However, in highly demanding conditions, such as metal ore mining, the service life of conical picks is significantly limited. Therefore, researchers are constantly searching for methods to extend their operational lifespan, i.e. to improve their durability. Appropriate laboratory testing procedures are required to evaluate the durability of conical picks and compare various design or material solutions. The article presents a method for assessing wear rates of conical picks with the use of a dedicated laboratory test rig. A comprehensive procedure for quantitative quality assessment, including the unit price of picks, has been proposed. This approach enables direct comparison of products offered by different manufacturers, facilitating the selection of the most cost-effective and efficient solution. The procedure has been validated in practice during research commissioned by Polish coal companies and in numerous independent research projects. Several methods for calculating wear rate indicators have been discussed. The analysis has confirmed the robustness of the proposed methodology and its resistance to undesirable fluctuations in selected parameters. The paper outlines various formulas for determining the mass wear rate of conical picks and discusses alternative approaches to calculating performance indicators. The developed procedure allows the selection of picks to be optimised by adjusting the weighting of price-related factors according to current financial and operational requirements. The applicability of the method has been illustrated with two case studies: the first relates to tender procedures conducted by a Polish coal company, whereas the second concerns research aiming to identify materials or coatings capable of enhancing the durability of conical picks relative to widely available commercial solutions.

Mechanical mining is extensively employed in the mining and construction industries. Conical picks are essential cutting tools that experience wear during operation, necessitating their timely replacement. Prolonging the service life of these picks can significantly enhance mining efficiency and provide economic benefits. This article examines the wear of conical picks used in mining machines and explores quantitative methods for assessing their wear rates. We have compared two different types of assessment: the mass and volume methods. Laboratory tests were conducted under controlled conditions to measure the wear of the picks, utilising a laboratory scale, 3D scanning, and Archimedes’ principle. The accuracy of these methods was evaluated by calculating both the wear indicators’ maximum and mean squared errors. The findings reveal that both methods produce similar results under standard conditions although there are differences in accuracy. 3D scanning, while slightly less precise than the Archimedes method, offers the significant advantage of generating a 3D file depicting the tool’s wear profile. In contrast, the Archimedes method is characterised by a higher repeatability and accuracy. The decision to employ mass or volume-based indicators should depend on the objectives of the test: volume measurements are recommended to compare structurally different picks, while mass measurements are adequate for picks of the same type. In summary, both methods demonstrate high accuracy and can be effectively applied in engineering practices.

The proper selection of cutting longwall winning machines for specific mining and geological conditions requires the development of an appropriate algorithm. The appropriate selection of a machine (shearer) is closely related to acquiring a high concentration of exploitation from the given longwall. That is indispensable, especially taking into consideration the growing cost of mining, as well as the depth of coal seams. In this article, an algorithm showing the selection of longwall winning machines has been presented. The algorithm has been created based on results of research on the processed coal’s mechanical properties. Analysis of the mining process, especially in difficult conditions, shows that in order to define a drum longwall shearer’s range of usage, the coal’s properties which have a significant impact on the mining process must be determined. The above also influences the technique, technology and effectiveness of mining—they impact the effectiveness of the winning machines. In connection to this, the cutting heads should be chosen and designed based on those factors, as well as any performance forecasts. As representative values the following have been chosen: workability index (WU_B), resistance to unidirectional compression (R_c), and energy consumption of the mining process (TE).

Additive manufacturing, or 3D printing, has become very common in professional applications in many industries. The 3D printing technology is especially suitable for making prototypes, demonstrators and small-batch production. The stiffness and strength of 3D prints depend on many factors, including among others infills, which are specific to this technology, as well as the orientation of the object during 3D printing. Where the stiffness or strength of an element is crucial, the only way is to empirically assess its properties. The advantage of 3D printing, i.e. incomplete infill of the interior of an object with the use of different types of infills (patterns) and different amounts of material, means that its mechanical properties differ from those of a solid element. The application of numerical tests, i.e. the finite element method (FEM), requires the creation of a 3D model while taking this infill into account. The modelling of elements for performing numerical strength calculations is time-consuming and labour-intensive. The article presents a proprietary original analytical method for generating various types of infills with varying infill density. The method was developed for typical infills (Grid, Triangular, Honeycomb). It was next implemented in the CAD environment using the iLogic tool of Autodesk Inventor. As a result, a tool for creating 3D models of objects consistent with those obtained from 3D printing was obtained. The method and tool were verified. Next, the influence of selected parameters of the 3D print on its mechanical properties was presented on three real objects. The results of numerical analyses revealed measurable benefits of such tests. The research conclusions also constitute recommendations for selecting the type and infill density of an object and its orientation in the printer with regard to the strength and stiffness obtained.

Battery-powered electric machines have been replacing classic combustion vehicles for many years in the automotive and heavy industry. This change has a positive impact on the environment and, in the case of working machines, also on the safety and comfort of operators. In underground mining plants, due to limited working space and difficult environmental conditions, the use of battery-powered electric vehicles (BEVs) in place of combustion machines with diesel engines brings even greater benefits in terms of the operator’s work conditions. This article presents the results of comprehensive tests of two roof bolters in a BEV and a vehicle with a combustion engine. The tests were performed in underground conditions, during normal operation of the machines. They covered many aspects of machines’ operation, such as availability; traction properties; battery use; cooling system; efficiency; costs; safety; and ergonomics in terms of gas emissions, noise, vibrations, and generally understood work comfort. The research results showed a significant advantage of the battery-powered machine over the one with a combustion engine. The tests in question are unique due to their scope and the fact that they were carried out in underground conditions, during normal operation, both for the internal combustion machine and its battery-powered equivalent.

W pracy przedstawiono budowę oraz rozwiązania konstrukcyjne układów zasilania i napędowego ładowarki LHD z innowacyjnym układem przeniesienia napędu typu in-wheel drive. Przedmiotowa ładowarka jest pojazdem typu BEV z wymiennym magazynem energii. Przeznaczona jest do pracy w warunkach podziemnych kopalni niezagrożonych wybuchem, zwłaszcza kopalni rud metali. Opracowana konstrukcja zawiera cztery niezależne, elektryczne układy napędowe usytuowane w zabudowie kół jezdnych. W pracy przedstawiono wyniki badań symulacyjnych, umożliwiających oszacowanie wymaganej mocy napędowej i zapotrzebowania na energię elektryczną w różnych reżimach i warunkach pracy ładowarki. Wyniki obliczeń wykorzystano do określenia parametrów podzespołów układów napędowych oraz pojemności baterii akumulatorów.

The need to classify rocks in terms of workability stems primarily from the need to choose the appropriate, most effective diagnostic method (DM) and way of mining the given rock. Studying and measuring the workability of rocks is extremely difficult due to the fact that workability depends on many various factors. There are many DM for determining the workability of rocks, but none of them take into account the influence of all factors, hence the obtained results are only indicative. In the article, many DM and ways of determining the cutting resistance with the use of various devices are presented and characterized. The principles of their operations are presented, as well as the DM of measuring the cutting resistance and its utilitarian usefulness in forecasting the selection of mining machines on the basis of cutting for specific mining and geological conditions. The core of the problem is confirmed by the number of covered DM and tools in various research centers around the world. In the article, new tools measuring and evaluating the mechanical properties of the coal solid, all created in Poland, are presented. Their structure, principles of their operation, as well as the innovation of these solutions, are all presented. In this article, their ad-vantages and disadvantages are highlighted, as well as showing the DM which best represents the way of work of the winning machine. Therefore, the results achieved through the aforementioned DM can be understood as representative values.

Development of mineral deposits located at significant depth may be carried out by means of vertical shafts. Shaft sinking technology usually requires a number of works to be carried out, including the selection of appropriate excavating techniques adapted to geological and hydrological conditions, including natural hazards. The production technology and the machines used determine the level of sinking costs and execution period. The article discusses the excavating technologies currently used across the world. Then the assumptions, concept and construction of a new generation of shaft sinking system were presented. The proposed new solution of the system and the excavating technology allow for parallel execution of key processes related to winning, loading, transport and shaft wall-side lining, which significantly increases the progress of sinking. The shaft sinking system was created by scientists from AGH in cooperation with KOPEX-Przedsiębiorstwo Budowy Szybów S. A. and Instytut Techniki Górniczej KOMAG.

In the mining and construction industries, hand drills are used to carry out many processes related to excavation and auxiliary works. Hand drilling is commonly applied for making small diameter holes, especially in hard-to-reach places. In the case of manual drilling, an important parameter is drilling resistance, especially torque. Drilling tools are subject to wear, which has a negative impact on the process of drilling, including resistance and efficiency. A blunt tool lowers the drilling speed and puts more strain on the operator. The article presents the results of laboratory tests of selected parameters of the drilling process carried out with a hydraulic rotary drill. The tests were performed with the use of new drill bits as well as drills characterized by a various degree of wear. The tests were carried out for popular, frequently applied rotary drilling tools, on a unique laboratory stand that enabled setting the feed force and measuring the torque, rotational speed, drilling path, drilling speed as well as the in and out pressure of the drill. A number of characteristics were determined as a function of time and depth of the drilled hole. It was found that tool blunting affects the drilling process in various