Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie Number 09/2016

This paper contemplates the determination of the duration of the final depression stage of mining land. The final depression stage duration is the time difference between (1) the end of mining at a given geographical point (or removal of the mining face from that point to a distance exceeding the mining impact range) and (2) the actual cessation of the depression forming process at that point. The paper characterizes a surface depression forming process, caused by underground mining, as evidenced by field geodetic survey at one of the mining facilities operated by Jastrzębska Spółka Węglowa and identifies the individual stages of that process. To determine the contemplated duration with varying mining and geological conditions it was assumed that the significant factors contributing to the duration of mining effects on land shifting include: mining depth, mining front advance rate, depleted bed portion shutdown method, and the rock mass characteristics within the contemplated mining operation. The paper focuses on a single case of a specific mining land in the vicinity of a specific mine, where the majority of the listed contributing factors exhibited great similarity. In order to obtain the simplest empirical relationship, it was assumed that the mining depth is the most critical factor at the showcased mine which determines the duration of mining land shifts. The analyses of available field survey measurements results enabled selecting 7 cases of mining land shift cessation within a field mined between ca. 600 m and ca. 725 m of depth below the terrain level. Based on the established durations of these shifts, a regressive linear relation was determined and expressed with the formula (3). The formula outputs an approximate final stage duration of rock mass shifts. The formula can be applied to mining conditions in the areas where there are no survey measurement results available for an explicit determination of the actual cessation of mining land shifts.

For many years the mining and quarrying is among the most dangerous fields of human activity. This fact causes the need of analyze the causes and effects of this accidents. The article concerns the analysis of accidents occurred in the mining and quarrying, and is based on and statistical data and review of the literature. The aim is to show the number of accidents, to discuss of risks, causes and effects of dangerous events. It can lead to specify preventive measures.

Shaft VI at KWK Budryk (Budryk Hard Coal Mine) is the deepest mine shaft in Poland that opens the deepest on-site mining level, located at 1290 m below the terrain level. The shaft was sunk in two stages: down to 1034.3 m below the terrain level between 1979 and 1985, and continued to the target depth of 1320 m between 2011 and 2015. The second sinking stage involved continued operation of a shaft hoist, which remains in service to this day. The shaft hoist required installing a number of equipment, structural solutions and safety components (topside and in-shaft), as well as adapting the operating schedules of two shaft hoists: the sinking shaft hoist and the mine service shaft hoist, with the latter operated for the carriage of men, materials and output, and for inspections, repairs and overhauls. A major challenge for the contractor assigned to this project was to execute their work in a complete processing cycle, including blasting and concrete lining of the shaft. The sinking of this shaft and construction of the mining level at 1290 m enabled opening and mining beds of high-value coking coal without opening a sub-level completion.

For filling of underground voids mainly fine-grained slurries, are used, generally made from fly ash or bulk mineral binders. In case of large voids or hydraulically interconnected systems of voids (Fig. 1) aggregates can be used to minimize uncontrolled migration of fill slurries to distant parts of caved rock mass (Fig. 2). Aggregates can be located as dry material thrown on the bottom of the void directly from pipe or horizontally, with use of special ejector at the end of the pipe (Fig. 3). Dimensions of created piles can be calculated on the basis of kinetic energy and internal friction angle of the aggregates. When large aggregates grains are used, the piles contain high volume of voids, which must be filled with a slurry being able to fully fill the voids and stabilize the pile structure. In laboratory tests, filling properties of different fly ash – water slurries have been conducted using a large diameter pipe filled with aggregates of determined volume of voids (Fig. 4). Loss of solids and average velocity of flow through the aggregates have been measured by differentiated concentration of mixtures and pressure head (Tab. 1). The results show that the build-up of filling in voids increases with decreasing flow velocity (Fig. 5) and enhancing concentration of solids (Fig. 6), however both factors are strongly depended on general flow properties required for hydraulic transportation of fill slurries in pipelines.