The paper introduces a high-selective oil-shale mining technology and the first results of surface miner Wirtgen 2500SM tests. The technology allows to decrease oil-shale loses from 10-15% up to 5-7%. Mining process of the surface miner has a lower disturbing impact, which is topical in open pits and quarries especially in densely populated areas. The low level of dust and noise emissions and also very’ low vibration are arguments to mine oil shale with surface miner instead of drilling-blasting operations. The risk analysis for testing technology was elaborated.
The paper deals with risk management problems in Estonian oil shale mines. Investigations are focused on application of the method to determination of the quality of geological data. Various factors relevant to mining technology in Estonian oil shale deposit have been determined. For risk estimation, the empirical and judgmental approaches and the event tree were used. They allow determining the probability of the occurrence of geological features and its influence on the mining process. Analysis of obtained results showed that it is necessary to elaborate special methods for determination of the geological conditions in the mining area. The obtained information affords specialists to improve the quality of geological information and consequently the mine work efficiency. The analysis shows that the used method is applicable in conditions of Estonian oil shale industry. The results of the investigation are of particular interest for practical purposes.
This paper analysis the immediate roof (IR) stability by the deformation criteria for new room-andpillar mining technology with modern machines in “Estonia” mine. The new mining technology based on a blasting method to move from packaged to emulsion explosives, from 2.0 m to 4.0 m boreholes (FRANZ SCHELL machine) and on new undercutting (SMAG machine) method. With such equipped new technology the entry advance rates reached 3.8 m. As a result of such greater advance rates the situations with unsupported room length up to 5.5 m with decreasing the stability of IR can be expected. The analysis of IR stability based on an in-site underground testing by the leaving bench-mark stations and convergence measurements. The main targets of this study to determine the main parameters for supported/unsupported IR deformation in areas with great entry advance rates and risk analysis concept elaboration.
Health risk assessment related to water quality and microcystin contamination of water in the Kuibyshev Reservoir was conducted in August 2012 during the period of algal bloom. The health risk during recreational activity was estimated for potential exposure to extracellular microcystins. Microcystin content in water measured by the indirect competitive ELISA method was in the range from 0.21 to 26.96 μg L−1. The results of the present study show that the health risk can reach a dangerous level even at 1 h of exposure due to the high concentration of extracellular microcystins in the water.
In this paper, the modeling, analysis and monitoring of a room-and-pillar mining technology in an Estonian underground mines is presented. Technology is based on continuous miner as the primary production machine. Many technical and economic parameters o f production, including loss of useful minerals, depend on a correct choice of the sizes for these elements. Without the account o f reological properties o f covered rocks, in particular the character of change o f their long strength, the account of the sizes of rooms and pillars on a certain determined term is impossible. For the modeling, the existing room- and-pillars determination method by IMS and with formulas by V. Undusk, Visual Basic for Application in Excel, Maplnfo, and Fast Lagrangian Analysis of Continua was used. Model allows determining the parameters of spontaneous collapse of the pillars and\ surface subsidence, optimized the working parameters for continuous mining. Proposed method suits for stability analysis, failure prognosis and monitoring.
The processes of immediate roof exfoliation and pillars collapse accompanies by significant subsidence of the ground surface. Ground surface subsidence causes soil erosion and flooding, swamp formation, agricultural damage, deforestation, changes in landscape, ground water level decreasing and the formation unstable cavities. During experimental measurement of immediate roof absolute deformation on "Estonia" mine three earthquakes were registered. The main reason of investigation has served jumping characteristic of absolute deformation near a pillar after earthquake. Method of final elements for analysis of deformation modelling is used. Seismic risk assessment for underground constructions stability is presented in this study.
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