The processes of rock excavation and processing involve intense mechanical stresses on cutting, displacing, and transporting tools, inevitably leading to the phenomenon of dry friction wear. The factors influencing the intensity and mechanisms of wear are complex and interdependent, being conditioned by the physical–mechanical properties of the rocks, the geometric characteristics and materials of the tools, as well as the cutting process parameters (cutting force, feed rate). Previous studies have mainly addressed the global aspect of wear without delving into the microstructural evolution of the contact surfaces during the friction process. In this paper, through controlled tribometric tests, we have investigated in detail the abrasive wear mechanisms of metallic materials in contact with different types of rocks, with an emphasis on the role played by surface roughness and the mineralogical properties of the rocks. Experimentally, we varied the applied forces and the number of friction cycles to simulate different working conditions and evaluate how these parameters influence wear intensity and surface morphology evolution. Microstructural analysis of the samples, combined with roughness measurements, allowed the identification of the predominant degradation mechanisms (abrasion, adhesion, fatigue) and their correlation with the material properties and the friction process parameters. The results have shown a strong correlation between the wear capacity of rocks and their petrographic properties, such as hardness, porosity, and hard mineral content. It was also found that the roughness of the contact surfaces plays an essential role in wear mechanisms, influencing both the initiation and propagation of its effects. Depending on the experimental data, we have developed a classification of rocks based on their abrasive potential and proposed criteria for the optimal adoption of materials and working parameters for the tools of technological equipment depending on the type of rock encountered. The results of this study can contribute to improving the durability of tools, as well as mining equipment, and reducing operating costs.

Tailings dams are special constructions that are part of a complex of works related to the installations for preparing mining masses. These constructions play a role in the mechanical treatment of wastewater and the safe storage of sterile material resulting from ore processing. The closing and greening of tailings dams is achieved taking into account the general stability of the pond and its related constructions, as well as the integration into the surrounding environment of the surfaces occupied by mining waste deposits (tailings dams). This study presents the results of the hydrogeotechnical and stability study carried out on the Gura Roşiei tailings dam location. This analysis aims to evaluate the stability degree of the three compartments that comprise the tailings deposit in order to carry out the closing and greening works of the tailings dam, and to conclude whether the idea of raising them by 1.5–2 m with tailings is feasible. This study was based on field observations, geotechnical drilling, and physical–chemical analyses of the collected samples. Due to the shallow depth, the drilling could not highlight a hydrostatic level except for the areas with excess humidity, areas represented by certain lenticular intercalations of sandy dust that yield water very slowly. These areas are not continuous and cannot define a reference hydrostatic level. All situations were analyzed by four different methods that satisfy the static equilibrium of forces or moments (Bishop and Janbu) or simultaneously of forces and moments (Spencer and Morgenstern–Price). From the point of view of the stability calculations performed in the hypothesis in which the three ponds become active for the storage of tailings, assuming a corresponding piezometric level, the resulting safety factors are relatively close to the standard values (Fs ≥ 1.4) for the static analysis, and in seismic conditions, they are at the limit of equilibrium. The NE slope of pond No. 2 shows values below the standard safety limit for this type of work. Moreover, tailings dam No. 3 presented from the calculations as being totally inadequate for the elevation. From the obtained results, it was found that the location formed by the three compartments that comprise the Gura Roşiei tailings dam presents major disadvantages for a future storage of flotation tailings, being at the same time an imminent danger to the environment. Due to its reduced capacity to release water from its pores, the settled material is still in a saturated state, and it is assumed that the foundation land, comprised of the terrace deposits of the Abrudel River, is clogged at the interface with the settled material and unable to naturally drain the excess moisture from the dam’s body.

The equipment in underground mines provides a continuous production flow, depending on the way their quality is preserved during their operation. The TR-7A scraper conveyer subassemblies, which function in the Jiu Valley coal basin and are subjected to abrasion wear, showed a high failure frequency (chains, chain elevators, and driving and turning drums), as well as the hydraulic couplings and certain electric equipment of the same machinery. The data collected following the TR-7A scraper conveyer at work allowed the parameters to be determined that characterise the reliability and maintainability of the above-mentioned components, the failure modes, and their effects. Using calculation methods, the interpretation of the results has been facilitated, with a view to reducing maintenance costs and obtaining an 80% reliability for the components with the most failures, in the case of the TR-7A scraper conveyer.

The analysis of the behavior in exploitation of the extraction, transportation and utilization of hard rock type mineral substances proved that one of the most extended and aggressive forms of wear is abrasive wear. The effects of abrasive wear on the machine components and their economic implications are significant, especially due to the operational pauses coming up in the technological flows that serve specific activities. This study presents two ways of limiting the consumption of tamping tools for the railway machines that are submitted to abrasive wear, namely, by reconditioning with the help of electrodes for overlaying welding with alloys of preestablished characteristics; by executing cast cleats from composite material in which metal carbides were infiltrated by diffusion. The great number of cast cleats tested in exploitation allowed a reliability and maintainability analysis to be made using the Weibull++ program, including the determination of the necessary number of cleats for 5000 h of functioning. The results of the experiments performed to this end demonstrated that both the reconditioning and execution of spare parts, with the help of reusable materials, could be solutions for sustainability in several economic fields, especially in those where the production costs are high.

The rapid development of science and technology, and the restructuring of the mining extraction industry, bring about profound changes in the structure and complexity of technological equipment used in mining. In this paper, the Reliability Centered Maintenance (RCM) method has been applied to analyze the components of the KSW-460NE shearer machine, which fails quite frequently. The cutter drums do not match from a constructive point of view, and the concrete operation conditions, alongside the picks (being in direct contact with coal and hard inclusions) and guides are submitted to intense abrasion wear, showing a great number of failures. The data collected following the machine’s exploitation allowed parameter determination characterizing the reliability of the components mentioned, the manner of failure, and the effects. Using calculation methods, it has been possible to facilitate the interpretation of the result in view of establishing measures required to improve maintenance of the dominant components of the machine, determining replacement intervals, in accordance with an imposed reliability and maintainability. The results of the study assist in the choice of suitable hardening materials for the reconditioning of cutter drums and guides that are necessary for practical trials, by which their operating times, and replacement intervals, respectively, might be additionally improved.