Volume 27 (2021): Issue 1 (March 2021)

The mining sector is a particularly important field that has the ability to support the economic development of a country by supplying various mineral products that are used as raw materials in other sectors of activity. When the depth at which a deposit is located and the geological conditions allow, the exploitation of useful mineral substances is realized through open-pit mine. The aim of this paper is to analyze the malfunctions that could occur and cause susceptible incidents and that could have consequences on staff safety and the environment. These malfunctions can have different causes: either an internal origin of the mining unit, or in natural phenomena. In this paper are identified and analyzed the potential mining risks that may occur in the Roşia Poieni open pit mine. The guidelines underlying the identification of these risks took into account three main principles: reducing risks for people, ensuring their security and at the same time limiting the risks on the property, respectively the financial risk for the mining unit. Acknowledge these risks, allows the delimitation of areas that are directly or indirectly exposed to potential risks and the establishment of specific measures for prevention, protection and security regarding the realized activities. Depending on the potential mining risks identified, we have made a hazard map that can be used to develop a risk prevention plan, taking into account the presence of several types of risks that may overlap in the same work area of the quarry.

The underground mining of the rock salt deposit from Slănic started over 350 years ago, in bell-shape room (Ocna din Deal and Ocna din Vale) and in large trapezoidal rooms (Carol, Mihai and Unirea mines), until 1970, generating a volume of underground excavations of over 5.3 million m³. Over time, these large excavations have lost their stability (collapse of the mines to the surface and various degrees of instability of the Carol and Mihai mines), keeping only the Unirea mine in operation for tourist purposes. This article is a synthesis of the analysis with 3D finite elements, in elasto-plasticity, of the state of stress and strain developed around the excavations and highlighting the factors that led to the loss of their stability, focusing on the Unirea mine.

With the occasion of complex and detailed studies, conducted especially from the geotechnical point of view (between 2016 and 2019), on the North Pesteana mining perimeter (more precisely on the lignite open-pit with the same name) numerous areas affected by suffosion were highlighted, mainly located on the lower steps (steps III and IV). Starting from these observations, the present paper analysis the risk of suffosion phenomenon to occur in the case of the final slopes of North Pesteana open-pit. In general, as observed, these areas have small and medium sizes, and do not affect significantly the stability of the steps, being immediately remedied with the advancement of the work front. Also, it was observed that, with the advancement of the excavation fronts, the groundwater currents constantly entrain the fine particles from the aquifer formations, and therefore new such suffosion areas occur. Taking into account the fact that the exploitation of lignite in this perimeter is ending soon, it was considered as necessary to assess the risk of suffosion at the final slopes (long term slopes) in order to be able to identify appropriate measures to prevent future potential catastrophic events.

The Certej area is an area of gold mining activities with a history of several hundred years. The only activity with a significant share in the area was the mining activity, which provided the population of Certeju de Sus commune and its surroundings with the means necessary for a decent living. In the case of tailings dumps, the soil suffers a combined impact - by removing large areas of land from the natural circuit and by generating acidic water. The geology and morphology of the region, characterized by the existence of surfaces with different slopes, are natural causes that attribute different levels of vulnerability to land at the onset of degradation processes by erosion, landslides and excess moisture. All these bring limitations in the use of land on the main uses: agricultural, forestry, construction, etc. The paper aims to provide solutions for the reuse of these lands, their use by recultivation, the search for plant species adaptable to soil conditions. A relatively small number of species were determined on the tailings dumps in the studied area, the spontaneous vegetation is visibly stressed by the existing conditions. As such, the method of ecological reconstruction of freshly deposited tailings dumps by the method of forest recultivation is proposed.

The paper highlights a strong environmental impact due to a mining perimeter (Central Flotation - Baia Mare) in which significant quantities of complex and concentrated ores were abandoned without the most basic protection measures against environmental factors. The period of time since the cessation of activity has been more than 14 years, during which time an extreme reactivity took place, generating an acid drainage with very low pH and heavy metals exceeding hundreds and even thousands of times the maximum allowed values. These waters reach the natural receptors directly or infiltrate the groundwater. Another serious aspect is given by the fact that this site is located in the middle of the busiest community in Maramureș County (upstream of Baia Mare) and close to rural communities that practice agriculture and animal husbandry. Alongside the already existing environmental problems in the perimeter there is also added seepage of mine water through the exit of the tunnel from the Herja mine. Also adjacent is the Central pond with a supply of mine water and toxic dust.

The paper presents the attempts of acid and alkaline solubilization of the power plant ashes, using different chemical reagents, at different concentrations. Due to the mineralogical content of these ashes, was elaborated a technological flow for the recovery the iron minerals, resulting an ferrous concentrate containing noble metals. For their recovery from ferrous concentrate, were studied properties of gold, silver and platinum, the conclusion being that these chemical elements can be extracted, in economic conditions, with sodium hypochlorite.

The study focused on the model of estimating the risk of exposure of workers to global occupational vibrations / with local action on the hand-arm system. In order to estimate the risk of exposure to occupational vibrations, we developed a generalized mathematical model for estimating the risk of exposure to mechanical vibrations transmitted to the whole body / with action on the hand-arm system. This model is based on the statistical function of probability with exponential decrease (Gumbel function), and its argument is expressed either by the values of the weighted acceleration parameter or in the form of exposure points.

The paper present the issue of explosion risk assessment presented by the risk of accidental initiation of electrical detonating caps and pyrotechnic articles. The purpose of the explosion risk assessment is to establish appropriate protection measures to prevent or limit them.

Geodetic and topographic works determine the necessary information base and of major importance in the design and management of underground construction works (mining, hydrotechnics, roads, etc.). The efficiency and safety of these investments with special financial implications depend on their quality. In this context, the geodetic orientation of the underground topographic works was the main and permanent subject of study and analysis on which this scientific paper refers.

In areas with border extension (localities, mining areas, hydrotechnics, etc.) it is advisable to establish the positions of the points in a local system, the methods used being simpler and the results more precise. However, it is necessary to transcalculate the coordinates from the local system to the national projection system. A transcalculation method is assumed to ensure efficiency and accuracy.