Magnesium hydride, despite the decomposition temperature being incompatible with the operating temperature of a typical PEM cell, is still considered a prospective material for hydrogen storage. Hence, this paper presents new aspects of the influence of milling time on the structural changes and temperature of MgH₂ decomposition, with particular emphasis on the changes taking place in the first few seconds of the milling process. This paper presents qualitative and quantitative changes in the powder particle morphology determined using scanning electron microscopy (SEM) and infrared particle size analysis (IPS) systems. The crystallographic structure of the powders in the initial state and after mechanical milling was characterized by X-ray diffraction. The decomposition temperature and activation energy were determined by the differential scanning calorimetry (DSC). Changes in the activation energy and decomposition temperature were observed after only 1–2 min of the milling process. Two basic stages of the milling process were distinguished that impacted the MgH₂ decomposition temperature, i.e., mechanical activation and a nanostructuring process. The activation was associated with the initial stage of particle size reduction and an increase in the fraction of fresh chemically active powder particle surfaces. On the other hand, the nanostructuring process was related to an additional decrease in the MgH₂ decomposition temperature.

The aim of the research presented in this work was to verify the occurrence of the thermoelastic effect in compacted steel wire ropes for future research applications and TSA methods. It was examined using a Testo 890 thermal camera during tests consisting of 10 cycles of loading of rope samples to levels under the yield stress, performed on a tensile strength machine. Average measured changes of temperature caused by a 1000 MPa change of stress were 0.8 K during loading and 1.0 K during unloading. It was found that rapid unloading caused temperature changes that were closer to the theoretical values calculated for an isotropic body and adiabatic conditions. Probable reasons for those differences were investigated. Furthermore, temperatures of samples recorded after each cycle of loading were analysed. Heating of samples during cycles of elastic elongation was observed, pointing to exothermal processes taking place in the internal structure of the ropes. Application of IR cameras to detect dynamic load changes using the thermoelastic effect in steel wire ropes was proposed and evaluated. Usage of described novelty method in inspection of steel wire ropes during the operation was discussed.

In most rope transport devices, the used steel wire ropes are replaced with new ones after working for a certain period of time, or after reaching the acceptable level of wear. The operational safety of the entire system depends on the correct diagnosis of the condition of the working wire rope. This is not easy, because the working lives of the ropes are varied, and their wear depends on many factors, including random ones. This article presents three different aspects of the work of steel ropes in mining-shaft hoists. What they have in common is a stochastic approach to interpreting the level of rope wear. The process of progressive wear due to fatigue breaking of wires is presented as the first example. This process is non-linear with a strong upward trend, which, in the final stage, turns into a phase often referred to as “explosive”. The rate at which subsequent wire breaks appear is influenced by numerous random factors, e.g., in the form of different methods and materials from which a given rope is constructed. However, the character of the progressing wear process is most affected by the random distribution of stresses experienced by individual wires and the randomly variable nature of the working environment. The second aspect presented in this article is an attempt to determine the probability of wire breaks of the rope. This was presented on the example of wear of the hoisting rope of a mining-shaft hoist. The last aspect of a stochastic nature, which is discussed in the article, is the issue of separating individual components of this distribution from the multimodal distribution describing the tensile strength of the rope wires, possibly of a normal character. Modern methods of analysis allow such distributions to be assigned to specific structural elements of the wire rope. This gives information about which structural elements of the rope wear faster or unusually and, consequently, determine its strength. This was presented on the basis of the results of strength tests of the wires of the mining-shaft hoist rope, which broke due to excessive corrosion wear of the inner strands. The presented examples explain only a short part of randomness in the description of working ropes, but the intention of the authors is to draw the attention of the personnel responsible for their safe operation to unavoidable random factors.

The computation of energy dissipation in mechanical protective systems and the corresponding determination of their safe use in mine shafts, requires a precise description of their bending and elongation, for instance, in conditions of dynamic, transverse loading induced by the falling of mass. The task aimed to apply a fast parallactic rangefinder and then to mount it on a test stand, which is an original development of the Central Mining Institute’s Laboratory of Rope Testing in Katowice. In the solution presented in this paper, the measuring method and equipment in which the parallactic laser rangefinder, provided with a fast converter and recording system, ensures non-contact measurement of elongation, deflection or deformation of the sample (construction) during impact loading. The structure of the unit, and metrological parameters are also presented. Additionally, the method of calibration and examples of the application in the impact tests of steel wire ropes are presented. The measurement data obtained will provide a basis for analysis, the prediction of the energy of events and for applying the necessary means to maintain explosion-proofness in the case of destructive damage to mechanical elements in the mine atmosphere. What makes these measurements novel is the application of a fast and accurate laser rangefinder to the non-contact measurement of crucial impact parameters of dynamic events that result in the destruction of the sample. In addition, the method introduces a laser scanning vibrometer with the aim of evaluating the parameters of the samples before and after destruction.

Comparative testing of Cable bolt and Wire rope laCing resistanCe to statiC and dynamiC loads the conduction of mining activity under the conditions of rock bursts and rock mass tremors means that designers often utilise support systems comprising various configurations of steel arch, rock bolt and surface support. Particularly difficult geological and mining conditions, when wire mesh does not provide sufficient dynamic resistance, it requires an additional reinforcement with wire rope lacing in the form of steel ropes installed between the bolt ends and fixed to them by means of various rope clamps (e.g. u-bolt clamps). Bench tests were conducted to compare the strength of wire ropes under static and dynamic loading. the tests involved wire ropes with an internal diameter of Ø15.7 mm. tests under static loading demonstrated that the cable bolts transferred a maximum force F smax = 289.0 kn without failure, while the energy absorbed until failure was E 1s = 16.6 kj. A comparative test result analysis for the wire ropes used in the bolt designs revealed that the influence of dynamic loading forces has a significant effect on reducing the rope load capacity, which results in the brittle cracking of the wires in the rope. Although the average dynamic force leading to wire rope failure F dmax = 279.1 kn is comparable to the minimum static force F min = 279 kn defined in the relevant standard, the average energy E 1d absorbed by the cable bolt until failure is 48% lower than the energy E 1s determined for wire rope failure under static loading. Furthermore, cable bolt failure under dynamic loading occurred at an impact velocity of the combined ram and crosshead masses ranging within v p = 1.4-1.5 m/s.

Pulling chains are one of the most critical components of a plough longwall system. Their failure is hard to predict and results in costly and lengthy downtimes. Measurements of the actual forces acting on a plough chain are needed as they can provide important information about the nature of their operation and contribute to preventing their wear and failure by supplementing data gathered by a plough control station. In this work, a strain gauge system for the measurement of the forces in a plough chain is designed, manufactured and tested under real conditions for the first time. Constructed using a cylindrical strain gauge and widely available electronic components, the finished sensor was calibrated on a testing machine and used to measure forces in a 42 × 137 plough chain at LW Bogdanka. Measurements conducted under real conditions show that forces in the chain during steady ploughing does not exceed 400 kN. However, the forces peaked to up to 728.6 kN at certain points in the operation. The implications of such events are discussed. The device allowed for successful measurements of forces in difficult conditions of a mining plough longwall and provides new information on their course and characteristics, which is very valuable for plough operators and chain-life predictions. This work suggests the further integration of force sensors into longwall plough system.