The steels from which the components of mining machinery are constructed must be based primarily on knowledge of their behaviour under environmental conditions and of the excavation technology. Secondly, the structural changes undergone by the materials due to mechanical and thermal processing and the stresses generated by the action of excavation forces that can induce internal stresses at a level that is difficult to determine must be taken into account. Determining the level of structural and mechanical degradation involves sampling the load-bearing structure elements of the excavation and storage machinery for analysis of the mechanical and chemical properties of the component materials. The paper focuses on issues related to the structural and mechanical degradation of steel as a material for parts of mining machinery. In this paper, a methodology for evaluating the degree of structural degradation of three types of bucket wheel excavators with different operating hours (ERc 1400-30/7-07 with 50,400 h, ERc 1400-30/7-08 with 69,264 h, and SRs 1300-26/3.5 with 112,000 h) is proposed. The methodology aims to provide a quantitative assessment of the structural degradation by considering the specific elastic limit of the material used in the machines and the number of hours of operation. This method uses a minimum set of destructive mechanical tests, such as tensile, resilience for three working temperatures, chemical analysis, and durometry on resistance elements taken from the machine, as well as the use of Weibull analysis. By combining this information with the number of hours of operation, a comprehensive evaluation can be made to determine the extent of degradation and potential maintenance requirements. The use of a minimum set of mechanical tests ensures an efficient and cost-effective approach to assessing the structural integrity of these machines. The metallographic analysis highlighted a predominant and defined form of grain rearrangement in the E14-07 machine after only 50,400 h. The constituents identified in the samples taken from the three machines are ferrite and pearlite. The highest hardness of the samples was recorded for the E14-08 machine, with values between 162–165 HV10. For bucket wheel excavators E14-07 and E14-08, the material structure showed elongated grains in the direction of deformation, compared to the material structure of E13-04, which has finely equiaxed grains. As a result of the research, final conclusions were formulated.

Corrosion is a major problem in the mining industry, significantly affecting the durability and reliability of mining equipment. In order to better evaluate and understand these effects, in the first part of this study, the analysis by the finite element method of the metallic structure of the rotary arm of an ERc 1400-30/7 bucket excavator type, produced in Romania in 1985, is presented. This paper presents an analysis of the impact of corrosion on the structural integrity of mining equipment. The focus of the research is on the use of advanced spectral analysis methods and the implementation of wavelet analysis. These methods allow an increase in the degree of accuracy of the information and results obtained. The study also focused on the impact of corrosion on the natural frequencies and structural changes in mining equipment, which were evaluated based on advanced methods of structural analysis. The obtained results show that corrosion deeply affects the dynamic behaviour of the metallic structure, leading to significant changes in the dominant frequencies. It was found that the measured dominant frequencies show a tendency to increase with the increase of structural degradation, an observation that is consistent with the physical aspects of the phenomenon.

The deep underground salt cavities have the advantage of allowing storage of hydrogen at higher pressures than surface installations. Worldwide, in the 2020s there were 4 functional sites of salt caverns used as hydrogen deposits, three in the United States and one in the United Kingdom, at an average of 600,000 m3 capacity each at pressures varies between 50 ÷ 150 bar in the United States and 3 x 70,000 m3 at a pressure of 45 bar in the United Kingdom [1, 2]. From 2020 until now, there is an increase in the salt deposit development for hydrogen storage, expecting to account for about 18% of global energy demand by 2050 [3]. Near Vadu locality, Constanta County, Romania, there are sald deposits located between 705 m and 905 m, respectively 1542 m and 1778 m, offshore in the Black Sea continental shelf. The study consists in determining the storage capacity, at the two drilling depths, for reliable projects of hydrogen storage, for Romania's Energy Strategy, leading to a reduction in the carbon footprint at 70% in 2050 compared to the levels recorded in 2008 of CO2 emissions per transport unit for all the civilian or military transport ships [4, 5].

Cellular asymmetry is an important element of efficiency in the compartmentalization of intracellular chemical reactions that ensure efficient tissue function. Improving the current 3D printing methods by using cellular asymmetry is essential in producing complex tissues and organs such as the liver. The use of cell spots containing at least two cells and basement membrane-like bio support materials allows cells to be tethered at two points on the basement membrane and with another cell in order to maintain cell asymmetry. Our model is a new type of 3D bioprinter that uses oriented multicellular complexes with cellular asymmetry. This novel approach is necessary to replace the sequential and slow processes of organogenesis with rapid methods of growth and 3D organ printing. The use of the extracellular matrix in the process of bioprinting with cells allows one to preserve the cellular asymmetry in the 3D printing process and thus preserve the compartmentalization of biological processes and metabolic efficiency.

The paper analyses the phenomenon of mining machinery fatigue, focusing on the Bucket Wheel Stacker-Reclaimer KsS 5600/3800x40 machine. To evaluate fatigue cycles under variable and non-periodic force conditions specific to this type of machine, Dirlik method and spectral analysis are applied. Dirlik method provides an innovative approach to stress spectrum analysis, taking into account the complex distribution of stress amplitudes during coal stacking operations and their deposition on the conveyor belt. Spectral analysis provides detailed insight into the frequency distribution in the dynamic response of Bucket Wheel Stacker-Reclaimer. This analysis allows the identification of the dominant frequencies associated with the charging and discharging cycles. The results obtained have significant implications for the optimisation of operations and the effective management of fatigue within this specific equipment.

This work presents an integrated energy production and storage system based on Compressed Air Energy Storage (CAES), implemented within a surface lignite quarry. The proposed approach enables the reintegration of closed, degraded, or closed mining areas into the economic circuit while supporting environmental restoration, including the conservation of local flora and fauna. The concept capitalizes unused quarry surfaces and tailings dumps by installing photovoltaic panels on these deposits. In addition, artificial underground caverns are created at the quarry face using ecological concrete and segmented linings made of prefabricated reinforced concrete rings, designed for compressed air storage. In Romania, existing CAES initiatives are limited, mainly consisting of small-scale projects of up to 1 MWh, alongside a larger proposed project of approximately 300 MWh using external vessels, often associated with long investment payback periods. This study proposes a scalable alternative by integrating renewable energy generation with large-scale storage directly within lignite quarry perimeters. The system aims to achieve an estimated annual energy production of approximately 100 GWh per cavern, offering both economic and environmental benefits.