Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie Number 08/2015

The paper presents an extract of results of the research work carried out as part of the research task No 8 “Development of a gas monitoring system for immediate shut-down of longwall machines and electric equipment in the case of a sudden release of methane”. This task has been a part of a strategic project “Improvement of a work safety in mines”. The origins of the strategic project and the goal of the task 8 – minimizing a response time of the system (shut down of electric power) to a sudden release of methane to a working – have been reminded in the paper. The results of analysis of the obligatory rules and directives regarding the requirements for the new system have been discussed. The metrological and functional requirements for methane-meters and other significant requirements resulted from the experience of use of safety systems have been presented. The new system will allow a user to extend methane monitoring at longwall areas and in particular it will simplify a control of places located outside areas monitored by the systems currently used.

Since inclination of a structure from vertical plane is the most substantial nuisance for users, in case of large values it may impact critically stability and strength of structural elements; in justified cases it is necessary to restore buildings to their vertical condition by rectification process. In case of buildings to be erected, in the area threatened by possibility to incline heavily, solutions adjusting a structure for rectification may be implemented at the stage of their designing and erection.

Goal of this paper is description of technical opportunities to adjust building objects to the rectification process (if necessary), and discussion over designing and performance issues which occur in case of such buildings. There are demonstrated two examples of operations commenced to adjust building objects and to carry out their future rectification. The first example concerns public function building structure of which, because of a danger of discontinuous deformation under the building in form of a territorial fault, has been adjusted at the designing and erection stage. At the second example some issues have been discussed which occurred at the stage of rectification system erection under a pool bowl during modernization of the bowl.

An analysis of the tremor source mechanism allows to reconstruct the way of rock mass destruction in the focus zone. The most probable ways of seismic events generation may be determined using the method of seismic moment tensor inversion. Understanding the processes, which take place in the high-energy tremors foci, enables a proper assessment of the rockburst hazard with the use of seismological method. There are presented, in the article, results of the analysis of the focal mechanism of high-energy tremors generated during longwall mining of the coal seam 408 in the area of pillars for surface objects and underground excavations at “Bielszowice” Coal Mine. Calculated focal mechanisms of these tremors were clearly correlated to mining and geological conditions. Firstly shear predominated, caused by influence of mining edges in overlying coal seams (405/2wg & 405/2wd). In the most of tremors foci uniaxial tension and explosion predominated. Longwall mining in coal seam 408 caused change of stress equilibrium in pillars mentioned above and exceeding of compression strength of rocks.

Indirect methods of the output's fragmentation evaluation e.g. the Split Desktop 2.0. software, are finding right now much more wide application in blasting works assessment. The complex method of the muck pile fragmentation assessment is being presented in the article. The assessment was performed according to the addition analysis in the muck's pile cross-section According to the conducted research there were on average 3% more of the oversize rocks in the output. In the output's cross-section there were more fines product - around 18%. Results of the muck pile shape and it's throwback according to the SfM (Structure from Motion) modeling was included in the article. The SfM model has allowed to perform a detail evaluation of the output's geometrical parameters such as: height, length etc. The digital model together with the on-site vision allowed to determine that the blasting parameter were chosen properly.

The article presents how to reduce dust concentration using mobile dust collector build on the construction of transporter. Dusty air from the dumping of transporter and coal breaker is sucked to the dust collector using mining fan and is purified with wet method. Dust collector UO-1200 allows to reduce dust with efficiency 1000–1200 m3/min. The article shows also the results of using this solution in a coal mine for dedusting air at the inlet to the longwall panel.