Volumen 28 (2022): Heft 3 (September 2022)

One of the risks connected to fires underground is the throttle effect which may cause unforeseen smoke spread. This paper investigates the throttle effect for a blower fan and an exhaust fan case in a mine drift. The aim of the paper is to perform a parametric study on the throttle effect, varying influencing parameters such as the heat release rate and fan flow velocity. Data from fire experiments in a model-scale mine drift and results from CFD simulations were used during the study. It was found that the differences between the two fan cases were significant both in magnitude and occasionally in direction. For the base cases the throttle effect as well as the backlayering were more severe in the exhaust fan case. When increasing the heat release rate to 116 kW an increasing backlayering resulted, but the throttle effect was found to increase for the exhaust fan case and decrease for the blower fan case. The throttle effect decreased in the blower fan case as the gas density decrease levelled off, but the flow velocity increased even further, causing an increase in the downstream mass flow rate. This finding was confirmed by similar experimental results in model-scale mine drifts. The resulting mass flow rate induced by the fire plume changes was found to be higher than the externally imposed increase of the fan flow velocity. When increasing the distance between the fire and the exhaust fan, the backlayering increased and the throttle effect decreased.

A recently completed research focused on the development of a low-volume mining production and transportation prototype machine. By developing this new mining adapter, the number of machines used in the mine can be reduced. Its application in dimensional stone mining can reduce the expenses of mining companies. After the block stone has been cut around, the stone material can be moved with the machine. The cutting forces and power requirements are calculated for the chain speeds used in production. This paper shows the static stress analysis of two kinds of possible structures of the dimension stone mining adapter. Finite element analysis was used to determine the displacements and the effective stress distribution of the adapter.

The aim of the study was to evaluate the phenomenon of land tilting and the tilting distance as a secondary effect of surface coal mining in the Jiu Valley area, Romania. To evaluate the tilting phenomenon, through the two considered elements (inclination – Lt, tilting distance – Td) 16 control points (CP1 to CP16) were used whose coordinates were measured in the Stereographic 1970 projection system, the 1975 Black Sea elevation system at an initial moment (t₀) and at the current moment (t₁). The static method was used by GPS technology to measure the elevations of the control points. Through descriptive statistical analysis, a general characterization of the set of recorded values was obtained, and the ANOVA test confirmed the safety of the data and the presence of variance in the data set. From the analysis of the recorded values, a Spline type model was obtained that described the variation of Lt in relation to Td, under conditions of statistical safety ( ɛ¯ = 0.137302). Regression analysis facilitated the obtaining of equation-type models, which described the variation of Lt and Td in relation to the X, Y and Z coordinates of the control points (t₀, t₁), under conditions of statistical certainty (R² = 0.697, p=0.014 for Td variation according to Z₀ and Z₁; R² = 0.722, p=0.0094 for Td in relation to X₀ and Z₀). According to PCA, PC1 explained 61.303% of variance, and PC2 explained 38.697% of variance. The cluster analysis facilitated the obtaining of a dendrogram based on Euclidean distances, regarding the grouping based on the similarity of the control points in relation to the studied phenomenon, under conditions of statistical safety (Coph. corr.=0.957).

In order to comply with the provisions of the normative acts in the field of air quality (STAS 12574/1987 - maximum allowed concentrations of sedimentable powders [1]), it was proposed to build a water mist dedusting facility within the coal deposit to stop the dust emissions at the source. The installation must ensure long-term operation in harsh conditions, with resistance to wear and minimal maintenance: operating time 12-14 hours/day, 365 days/year. The dedusting plant is composed of the water house, the distribution network, the fog production plants and the electricity supply plant. The process used to create the mist is based on the use of high pressure pumps. The equipment consists of fog guns equipped with high-pressure water spray nozzles and dispersion fans that are purchased fully equipped including a remote control installation; 6 spray guns were provided.

As part of the company Geoscan Service S.R.L., I was contacted to investigate the possibility of using resistivity, refraction seismic data and MASW seismic to identify the stratification up to 15m deep so that the client could choose the type of drilling rig for installing the conductor in order to drill two water injection wells. The main problem in the choice of geophysical methods was the lack of detailed geological data for calibrating the obtained results, as the presence of groundwater, the thicknesses of the deluvial layer and the bedrock. The choice of geophysical methods and the work procedure are carried out according to the international standards in force, ASTM D6429-99 “Standard guide for Selecting Surface Geophysical Methods”, ASTM D5777-00 “Standard guide for Using the Seismic Refraction Method for Subsurface Investigation, “Standard Guide for Using the Direct Current Resistivity Method for Subsurface Site Characterization”, STAS 1242/7-84 “Geophysical research of the land by seismic methods”.

Globally, coal was and remains one of the main primary energy resources, being the cheapest option for power generation. Coal deposits are available in large quantities, its exploitation being done with more stable prices and less sensitive to a series of international events, but it has the disadvantage of significant additional costs, due to the technologies required to reduce emissions in the environment. Romania, one of the most important coal-producing countries in Europe, has a long tradition in the mining industry and has important coal reserves, which can ensure the continuity of production for more than 150 years. Unfortunately, after 1989, coal production in our country almost halved, mainly due to the decrease in mining activity and the reduction of coal consumption (both by industry, such as steel and households - for the heat consumed from power plants based on of coal). At the moment, Romania mainly imports coal, but the share of imported coal also decreased to a quarter compared to 1990.

After the cessation of mining activities, concerns for mining cadastre research are only sporadic. The present study aims at bringing up to date the evolution of the mining cadastre in the Romanian provinces with a mining book regime, territories that were until 1918 within the structure of the former Habsburg Empire. (Austro-Hungary since 1867). Several stages can be distinguished in the evolution of the mining cadastre in the areas shown. From the 16^th century until 1854 the principles and methods of the mining cadastre were set up. Between 1854 and 1924 the provisions of the Austrian General Mining Law of 1854 were followed. From 1924 to 1948, the mining cadastre provisions provided for in the mining law of 1924 and other specific regulations are applicable. After 1948, under the conditions of a statist regime, the mining record did not respect the principles of the mining cadastre previously assessed. After 1990, the new mining cadastre only partially takes over the classical principles and methods of the mining cadastre. The way of applying the mining cadastre was focused upon in the town of Borșa, a mountainous place where farmers had not formed cooperatives and where intensive mining was carried out until 2007. With the cessation of mining in Baia Borșa, the mining cadastre was reduced to inventories of some mining assets and sporadic cadastre registrations of some premises and settling ponds. The study analyzes the current situation and proposes some integrated solutions, mediated by GIS technology, aiming the introduction of the mining cadastre in correlation with the introduction of the general cadastre. In this context, GIS technology offers modeling tools that, for example, can assess the degree of suitability of the land for construction.

This paper presents the possibilities and benefits of using drones in mining operations. In the first part of the paper, aspects regarding the concept, the constructive elements of autonomous aerial vehicles, legislative provisions for the use of drones, elements of flight safety and the security of people are clarified. In the second part of the paper, the possibilities of practical use of drones in mining operations, the benefits and the types of expected results are presented.

Global warming and climate changes, as well as the contribution of fossil fuel to the accentuation of these phenomena are realities almost unanimously accepted. Therefore, the reduction of the coal ratio in the energy mix and its replacement with forms of energy without emissions is being discussed more and more frequently. Nevertheless, it is important that the impact generated in the environment by the alternative energy sources related to energy production does not exceed the shortcomings created by the steam power plants, as it seems to be the case of micro hydropower plants (MHC) located on the superior flow of mountain rivers. As it is difficult to compare the impact on the environment generated by two completely different energy sources, two indictors were defined and used in this sense that consider their ecological, economic and social performance. As a result of the evaluation of the impact and of the comparison criteria, the two indicators were used in the two chosen case studies, resulting that a steam power plant that operates in cogeneration has a superior eco-energy efficiency to a micro hydropower plant. Thus, following the carried-out studies, we believe that MHC can be recommended only under special circumstances such as providing electric power to areas difficult to reach without them injecting the produced energy into the National Energy System (SEN).