Paskov Mine Research Articles

Economic Assessment of Methods of Coal and Gas Outburst Prevention in the Extraction of Coalfaces

Abstract In this paper, the authors focused on the assessment of the individual methods to prevent coal and gas outbursts. The first part deals with a characteristic of this anomalous phenomenon and some basic methods of coal and gas outburst prevention. The second part presents the economic assessment of the costs necessary to ensure the possible prevention methods in the coalface 080 211 in the locality of the Paskov Mine, Mining Plant 3, OKD as, Czech Republic. In this coalface, a simulation method was used for calculating costs for the drift length of 100 m for the use of various prevention methods (irrigation, relief boreholes, relief blasting). The results show the cost of preventive measures during mining intended to eliminate and protect against the formation of coal and gas outbursts. The measures are compared applying the principle of the decision analysis. Four criteria are used for the mutual comparison of the methods (costs, effort, efficiency, time consumption). The comparison has shown that the optimal method to prevent coal and gas outbursts is irrigation.

The Calculation of Methane Concentration Emitted from the Coal Face

Abstract The Paskov Mine belongs to the company OKD, a.s. with the production of hard coking coal from 1970. The applied mining method is the slabbing method in controlled caving, excavating the coal pillar by means of coal plough equipment loading mine run on rake conveyers and securing the excavation area with individual hydraulic or mechanical supports. The coal face is planned as one of the coal faces in continuous extraction of the seam by a shearer. Using the shearer at mines in the Paskov Mine is not a novelty. Shearer mining represents some problems. Besides the hazard of methane-air ignition, there is a mixture of coal dust - methane - air, which is more dangerous even in the case of lower concentrations of dust and methane than their individual lower limits of explosiveness. A decision was made then that shearers would gradually be replaced with coal ploughs in all coal faces. The article contains the calculation of the volume of methane emitted as a result of excavation, determining methane concentration during excavation, lowering the hazard of methane layers being formed, and finally evaluating the suitability of the proposed system of the coal face ventilation.

Innovation in dewatering process of flotation tailings by study of particle interaction in colloidal environment

Summary Many mining operations produce tailings that dewater very slowly under self-weight consolidation. On way of reducing the water content of such tailings is by coagulation/flocculation processes (C/F processes). This paper describes a study using aluminium chloride and pre-hydrated aluminium salts as aluminium chlorohydrate – ACH (F1.2A, F1AM, FD15, FDM17H, F1S) and polyaluminium chloride – PACl (PAX-18) in dewatering of flotation tailing slurries, resulting from coal flotation in the coal preparation at the Paskov Mine (Czech Republic). Experiments were conducted at different temperature and mixing conditions to simulate full-scale conditions. The results point to a potentially technique for reducing the water content of tailings streams, thus increasing storage space, improving economic and environmental aspects.

Source reverberations, near-surface resonances, or Q? Comment on “The peak frequency of direct waves for microseismic events” (Leo Eisner, Davide Gei, Miroslav Hallo, Ivo Opršal, and Mohammed Y. Ali, Geophysics, 78, no. 6, A45–A49)

In a recent Geophysics Letter, Eisner et al. (2013) measure peak frequencies in velocity spectra of direct waves from microseismic events. The authors interpret these peak frequencies as being caused by attenuation and use them for estimating the effective Q -factor of the medium. Nevertheless, I point out a significant problem with these results, namely, that the authors’ model for the earthquake source is not accurate enough to allow the determination of Q for the surrounding medium. This can be seen by considering the following question: Do the Q values reported in Eisner et al. (2013) characterize the medium, the source model, or the spectral data for direct arrivals? Eisner et al. (2013) assume the first of these answers to be correct; however, careful analysis shows that the correct answer is actually the last one. In answering the above question, note that the Q and t * values measured by this method are not unique physical properties of the medium because they change whenever a different source model is used. The flat plateau at f f c in the Eisner et al. (2013) source spectrum is unrealistic, and yet this plateau is the principal tool of the authors’ method for Q estimation. If we use, for example, Brune’s (1970) model as a more accurate one, then the Q would be much larger than the values reported by Eisner et al. (2013) (see the subsection “Meaning of Q ” below). Thus, the inferred Q s follow from the assumed source model. However, these Q values still cannot be viewed as corrections to the source model because even after these corrections, the model fits the observations very poorly (see the subsection “Data fit”). Therefore, the Q values proposed by Eisner et al. (2013) can only be interpreted as the observed spectral-peak frequencies heuristically multiplied by traveltimes: …

Current induced seismic activity in the Paskov mine field (Ostrava region)

The aim of this paper is to present the results of an investigation of induced seismic events which occurred during mining in the coalfields of Plants Paskov and Stařic of the Paskov Mine which belong to the southern part of the Ostrava-Karvina coal mines. Some results obtained in the time period January 1992 – December 2002 have already been published, and therefore, are mentioned here only briefly. The paper is based on new results of seismological observations at the OKC, KLOK, STEB seismic stations operated by the Institute of Geonics AS CR and stations of the Green Gas DPB, a.s., Paskov. A total of 26 seismic events were monitored from January 2008 to February 2012, most of them were localized into the area under study. As for the energy span of individual events according to the energetic classification of the Geophysical Centre of the Green Gas DPB, a.s., Paskov, all seismic events in Table 1 were estimated within the limits E(J) .

Reducing Carbon Dioxide Emissions by Underground Storage in an Abandoned Coal Mine - an Initial Study/ Snižování Emisí Oxidu Uhličitého Ukládáním Do Opuštěných Podzemních Uhelných Dolů - Základní Studie

Abstract This article is a basic study dealing with the issues of underground storage of carbon dioxide generated from different kinds of activities. Carbon dioxide can be stored underground as a free gas; gas dissolved in water, or can be adsorbed in the rock mass and in the remaining seams. The technology for processing and storage of carbon dioxide is known as Carbon Capture & Storage (CCS). The article focuses on the possibility to store CO2 underground at the Paskov Mine in the Czech Republic.

Evolution of Microclimatic Conditions in Paskov Mine / Ewolucja Warunków Mikroklimatycznych W Kopalni Paskov

Abstract The main subject of this paper focuses on scientific and research activities conducted in the Institute of Mining Engineering and Safety of the VŠB-Technical University of Ostrava. Cooperation between the VŠB-Technical University of Ostrava and OKD A.S., the only representative of coal mining in the Ostrava-Karviná coal basin, has recently begun to develop again. This paper describes an example discussed in a certain study, which has been undertaken for the Paskov mine, OKD a.s., dealing specifically with the evolution of microclimate parameters in mines that depend on the progress of mining activity at deeper levels over a period of several years. To this end, a special program, aimed at determination of the necessary refrigerating capacity, was established at the VŠB-Technical University of Ostrava.

An indicative method for determination of the most hazardous changes in slopes of the subsidence basins in underground coal mining area in Ostrava (Czech Republic)

Considering growing population and decreasing mineral resource reserves, the issue of undermining has been and shall remain very topical. This study aims to identify the mutual connections between mined out panels of a deposit and the final manifestations on the ground surface related to deep black coal mining. On the grounds of the identified connections, the study describes a method to simplify a common evaluation of undermined areas according to building site categories. Within the study, a demarcation of the areas was conducted in two localities in Czech Republic influenced by the effects of undermining in the Upper-Silesian Basin. In the allotment of the CSM Mine, an area unsuitable for founding structures was defined from the centre of the worked out workings to the distance of 175 m from the panel's edge, for which the corresponding break angle is 78.3°. Similarly, in the allotment of the Paskov Mine, an area unsuitable for founding structures was determined to the distance of 500 m from the panel's edge, for which the corresponding break angle is 50.2°. This demarcation may be implemented prior to deposit mining being aware of several physical-mechanical parameters of rocks in the deposit's overburden. Having mined out a particular section of a deposit, it is recommended to verify the values of break angle using the method described herein. The study may be applied as a relatively fast and effective method to evaluate future land use for planning.

Determination of actual limit angles to the surface and their comparison with the empirical values in the Upper Silesian Basin (Czech Republic)

This study deals with the determination of the actual limit angles in the long-term formed subsidence basin in the Czech part of the Upper Silesian Basin (the remaining part lays in Poland). Here there was the most extensive underground exploitation of black coal in the north-east of the Czech Republic. A limit angle is absolutely decisive in the determination of deep mining influences in relation to the current and future utilisation of this territory. The two CSM and Paskov mine localities on the edge of the subsidence basin were selected for this study, since they could not have been affected by mining in neighbouring mines. On the grounds of the long-term levelling monitoring of points on the surface which started prior to mining, the horizontal distance between the mined out area and the undisturbed ground surface was identified. The impact of limit angle on the surface was calculated by means of the horizontal distance and the established mining depth. Such identified actual limit angles reached the values of 36° at the CSM Mine and 25° for the Paskov Mine. The calculated values are significantly lower when compared with the currently applied empirical values of 57° for the CSM Mine and 56° for the Paskov Mine. This means that the extent of the undermining effects is unambiguously wider by 611 m at the CSM Mine and by 883 m at the Paskov Mine. This study thus establishes the existence of a significantly vaster area influenced by coal deep mining than previously expected. The identified facts lead to the conclusion that regular revisions and follow-up updates of the empirically determined parameters are recommended.

Method of drilling of coal pillar

One of outputs of the research project of the Czech Mining Office “Protection of Employees against Consequences of Rock and Gas Outbursts” was the application of yet not used methods of coal mining in the conditions of the Czech Republic. The aim of these methods is an increase in the recovery of coal reserves blocked in residual pillars left. For the conditions of Paskov Mine (Ostrava-Karvina Mines company) [1], the method of mining by means of long large diameter boreholes was chosen. The contribution provides information on the application of this mining method abroad and in the Czech Republic in the Paskov Mine.

Reflotation of Coal Flotation Tailings using Foam Separation / Reflotace Černouhelných Flotačních Hlušin Pomocí Pěnové Separace

Abstract Froth separation is one of the new methods of flotation process in mineral treatment. This method allows a substantial increase in the size upper limit of separated grains. The contribution deals with the verification of the possibility of using the froth separation for retreatment of flotation tailings. For laboratory research samples of flotation tailings from the Paskov Mine treatment complex were used. The results confirmed the ability of froth separation to convert coarse coal grains into a concentrate. Grains with a grain size of 0.5 mm were successfully reflotated.

Engineering-geological conditions of the effect of a landslide from mining activity

Engineering-geological conditions of the effect of a landslide from mining activityThe paper deals with a slope deformation in Řepiště (Paskov), which is located between the towns of Ostrava and Frýdek Místek; Řepiště is situated in the Ostrava-Karviná District within the reach of the effects of mining activity. The deformation involves the Paskov Mine, which is the only active mine in the Ostrava section of the district. The study included mapping complemented with a geophysical survey using resistance tomography; along with the information obtained from the inspection, it provided an overview of the engineering-geological conditions of the slope deformation. The interpretation of the data obtained identified a very complicated structure, including several levels of slip surfaces. The landslide is thus a textbook example of slope movements with a very complicated geological structure occupying an extensive spatial area in the mining landscape and affecting the stability of a road running directly through its body.