Volume 28 (2022): Edition 4 (December 2022)

In the paper, special attention is paid to the sources that lead to soil and land degradation in Valea Jiului, as these are the components of the environment that are most affected by mining activities. Three sources of pollution are analyzed: dumps, mine yards and constructions, and mining and preparation activities chemically polluting of soil. Among the environmental changes, land degradation currently has the most important consequences for human settlements and economic activities, especially through induced subsidence processes and the presence of dumps with reduced stability. The authors of the article propose their own method for establishing a Global Land Degradation Index (GLDI) affected by mining activities in a mining perimeter (mine) taking into account the entire analyzed area (in our case Valea Jiului) and make a classification (in three classes) of this index.

A small increase in the relative humidity in the air in a coal deposit can cause a 1% increase in the moisture content of the deposit resulting in the probability of spontaneous ignition. By depositing the freshly extracted coal over the coal already in the deposit, there is a direct contact between the two surfaces that have different characteristics in terms of physical and chemical properties, so that the latter acts as a primer.

The coal with a higher temperature gives up the excess temperature to the coal with a lower temperature, thus initiating the formation of self-heating nuclei followed by self-ignition ones. The phenomenon is easy to observe in the colder periods of the season and especially usually after rain, when the vapors resulting from the exchange of temperature between the two types of coal are released into the atmosphere.

The common cause is the movement of water vapor through the deposit correlated with the adsorption on the coal granules. The heat of condensation of vapor at storage temperature is about 580 cal./gram of water. Condensing the amount of water required to increase the content from 3% of the weight of the coal to 4% leads to an increase in the temperature of the coal by more than 170C. This increase in temperature is sufficient to increase the oxidation rate by 5 times.

Starting from the importance of the mining industry and how it influences the environment, environmental components and human settlements, this study analysed the activity of Prodănești, Moigrad and Marca quarries, from Sălaj county and how their activity influences the environmental components, air, water and noise. The analysis focuses on the interpretation of the test reports for the years 2016-2019, imposed in the regulatory acts, by the environmental protection authority.

The Antonio polymetallic ore body is part of the Baița Plai ore deposit. Below the XVIII horizon, it has a medium slope, a height of approx. 81 m, an average extension of 200 m and a thickness varying from 4 to 36 m. Above this horizon, the orebody was mined in horizontal slices with integral backfill and the first 9 m high sublevel with rooms and pillars. In depth, below this sublevel, 6 more sublevels with a height of 12 m are mined with sublevel caving mining method. The design of the opening, preparation and exploitation of the deposit was carried out for a production capacity of 100 k tonne/year.

The Ocnele Mari rock salt deposit is exploited with small rooms and square pillars, on the horizons +226 m and 210 m. Following the exploitation of the lower horizon +210 m, the floor between the two horizons suffered instability phenomena, marked by fractures and cracks and local degradation of the pillars.Since the pillars at the two horizons have certain deviations from the coaxiality, the question was raised whether the instability phenomena were generated by the deviations from the coaxiality.This article presents the stability analysis of bearing structures, taking into account the actual geometry of pillars, 3D finite element analysis and analysis of safety factors at the ceiling level, calculated from 2D finite element models. The final conclusion is that the instability phenomena that occurred at the Ocnele Mari Saline were generated by the state of stresses and strains, produced by the spatial distribution of the underground voids and the geomechanical characteristics of the rock salt and insignificantly, by the deviation from the coaxiality of the pillars.

Monitoring the displacements and settlements of tailings deposits is necessary due to stability problems that may arise over time. The paper deals with the monitoring by means of topographical measurements of two tailings deposits located on a site in Simionești village, Cordun commune in Neamț county. Topographic measurements are used to monitor the movement of landmarks located on these deposits and the settlement behavior of the deposit, so that any stability problems can be detected in time.

The management of explosion risk at explosives warehouses allows ensuring the necessary premises for the development, in objective and specific conditions, of the necessary documents for these types of technical infrastructures, right from their design phase and the quantification of the degree of impact on the sites analyzed as well as the areas that are located in their vicinity. In the case of the quantitative evaluation of the explosion risk generated following the detonation of explosive materials, the estimation of the manifestation of hazards identified through the associated risk factors should be carried out based on scientific calculation algorithms and established grapho-analytical models. The paper summarizes part of the results obtained regarding the development of a methodological approach and specific application tools that allow the assessment of the major accident risks generated by explosive materials, the identification, formalization and structuring of the applicable safety requirements to reduce or eliminate the risks in explosive material storage sites.

The unprecedented increase, in the last decades, of risks, hazards and threats to the vital objectives of states and international bodies, simultaneously with the increase in their number and vulnerability, led to the sedimentation and establishment of the new concept generically called critical infrastructure. The sites where explosives are manufactured, stored and used can be considered as critical infrastructures, especially taking into account the criterion of the extent, the amplitude of the effects of an explosion produced but also the possible severity on the economic activity, the public and the environment. From this perspective, this article presents an analytical tool for modeling the dispersion of material fragments generated by the detonation of explosives based on the quantification of the impact of the throwing speed and the mass of the material fragments, taking into account the type of material and the loading conditions of the resulting debris. The developed tool resorts to the use of a statistical function, namely the probability density function for modeling different types of fragments resulting from explosion-type events.