Arch. Min. Sci., Vol. 61 (2016), No 3, p. 587600 Electronic version (in color) of this paper is available: http://mining.archives.pl DOI 10.1515/amsc-2016-0042 PAWEL WRONA*, JÓZEF SULKOWSKI**, ZENON RÓASKI*, GRZEGORZ PACH* PROBLEMATYKA I WYNIKI BADA WYPLYWU DWUTLENKU WGLA PRZEZ ZLIKWIDOWANE SZYBY KOPAL WGLA KAMIENNEGO Greenhouse gas emissions are a common problem noticed in every mining area just after mine closures. However, there could be a significant local gas hazard for people with continuous (but variable) emission of these gases into the atmosphere. In the Upper Silesia area, there are 24 shafts left for water pumping purposes and gases can flow through them hydraulically. One of them Gliwice II shaft was selected for inspection. Carbon dioxide emission with no methane was detected here. Changes in emission and concentration of carbon dioxide around the shaft was the aim of research carried out. It was stated that a selected shaft can create two kinds of gas problems. The first relates to CO2 emission into the atmosphere. Possible emission of that gas during one minute was estimated at 5,11 kgCO2/min. The second problem refers to the local hazard at the surface. The emission was detected within a radius of 8m from the emission point at the level 1m above the ground. These kinds of matters should be subject to regular gas monitoring and reporting procedures. Keywords: carbon dioxide emission, gas emission, gas hazard, greenhouse gas, abandoned mine, closed mine Emisja gazów cieplarnianych jest problemem dotyczcym wszystkich zaglbi górniczych wgla kamiennego na wiecie. Problem ten nie koczy si wraz z likwidacj zakladów górniczych. Jako najbardziej prawdopodobne ródla emisji metanu lub/i dwutlenku wgla ze zlikwidowanej kopalni uznawane s uskoki tektoniczne, zlikwidowane lub nieczynne szyby kopalniane, obszary wychodni pokladów wgla, krawdzie dawnej plytkiej eksploatacji itd. (Czaja, 2011; Dziurzyski et al., 2004; Sulkowski & Wrona, 2006). Wyplywy gazów cieplarnianych na powierzchni terenu po pierwsze oddzialuj negatywnie na stan atmosfery, a po drugie mog tworzy lokalne, tym niemniej przejciowe, zagroenie dla bezpieczestwa powszechnego. W pierwszym rozdziale artykulu przedstawiono obecny stan wiedzy na wiecie dotyczcy poruszanego zjawiska. Stanowilo to przeslank do podjcia bada, których rezultaty przedstawiono w kolejnych * ** SILESIAN UNIVERSITY OF TECHNOLOGY, 44-100 GLIWICE, UL. AKADEMICKA 2, POLAND. JAN WYYKOWSKI UNIVERSITY, 59-101 POLKOWICE, UL. SKALNIKÓW 69, POLAND. rozdzialach. Stwierdzono take, e w adnym kraju nie s prowadzone procedury pomiarów i raportowania emisji gazów cieplarnianych z obiektów tego typu. Nastpnie przedstawiono wyniki bada dotyczcych emisji dwutlenku wgla z wybranego, nieczynnego szybu górniczego oraz imisji tego gazu w otoczeniu szybu. Na obszarze Górnego lska pozostawiono 24 szyby kopalniane dla prowadzenia odwadniania. S to szyby aerodynamicznie drone. Do bada wybrano jeden z nich, nieczynny szyb ,,Gliwice II". Podczas bada wstpnych stwierdzono znaczce iloci wyplywajcego dwutlenku wgla przy braku obecnoci metanu w mieszaninie gazów. Jako, e emisja gazów ze zlikwidowanej kopalni ku atmosferze moe by porównana z emisj gazów ze zrobów do powietrza plyncego poprzez czynna kopalni (Krach, 2004; Drzewiecki, 2004), uznane jest, e zaley od wielu czynników (w tym glównie od waha cinienia atmosferycznego, ale take od rónicy gstoci gazów i powietrza atmosferycznego (Grzybek, 2012; Wrona et al., 2014). Harmonogram bada przewidywal okresowe pomiary od lutego do maja 2014r. glównie w trakcie zniek barycznych. Pomiary emisji prowadzono na trzech zidentyfikowanych otworach wylotowych w plycie zamykajcej szyb (Fig. 2-3). W kadym otworze przeprowadzono badania wstpne dotyczce okrelenia jednorodnoci koncentracji gazu w calym profilu. Do pomiarów prdkoci powietrza zastosowano metod trawersu ciglego. Stwierdzono, e najwiksza warto emisji dwutlenku wgla wyniosla 2,69 m3/min (Tab. 2), co przy uwzgldnieniu redniej gstoci tego gazu (1,9 kg/m3) odpowiada 5,11 kg/min. Otrzymany wynik jest wartoci chwilow, natomiast daje pogld na moliw skal maksymalnej emisji. Otrzymano take nowe wyniki dotyczce wplywu rónicy pomidzy temperatur gazu, a temperatur atmosfery na wielko emisji gazu. Dnia 14.03.2014 pomimo zniki barycznej o tendencji 0,53 hPa/h wielko emisji dwutlenku wgla dochodzila do 1,66 m3/min (Tab. 2). Natomiast 28.02.2014 pomimo spadku cinienia o mniejszej wartoci tendencji barycznej, wynoszcej 0,4 hPa/h, warto emisji byla najwiksza. Analizujc wyniki przeprowadzonych pomiarów psychrometrycznych powietrza atmosferycznego i gazu stwierdzono, e w pierwszym przypadku rónica temperatur gazu i atmosfery wynosila 0,1°C, natomiast w drugim przypadku 6,0°C. Pomiary imisji dwutlenku wgla wokól szybu ,,Gliwice II" prowadzono na poziomie gruntu i na wysokoci 1m nad gruntem w oparciu o zaloon siatk pomiarow (Fig. 3). W kadym z punktów pomiarowych pozostawiono detektor gazów MulitRae Plus (z automatycznym zapisem danych) na czas dwóch minut z ustawionym interwalem próbkowania 30 sekund. Otrzymane cztery wyniki dla kadego punktu nastpnie uredniono. Mapy izolinii stenia dwutlenku wgla wokól szybu Gliwice II wykonano w programie Surfer 8. Przyklad z 21.05.2014 przedstawiono na Fig. 5. Stwierdzono, e zasig podwyszonego stenia dwutlenku wgla moe siga 8 m od punktowego ródla emisji na wysokoci 1 m, a na poziomie gruntu moe t warto przekracza. Slowa kluczowe: emisja dwutlenku wgla, emisja gazu, zagroenie gazowe, efekt cieplarniany, zlikwidowana kopalnia, nieczynna kopalnia 1. Introduction The emission of greenhouse gases from abandoned mines is a common problem observed in every coal basin (Sulkowski & Wrona, 2006). In Poland, it was stated that closed shafts are the second most probable path of gas migration to the surface (Czaja, 2011) even though they are the most easily accessible places for possible emission detection. This thesis is the basis for the analysis and the results which are presented in this article. Experiences from other coal basins are summarized below. a) United States This problem was the point of research undertaken by the Environmental Protection Agency in 2004 (U.S Report, 2004).Their main conclusions are that annual methane emission from abandoned or closed mines can be estimated at 8-10% of the global value. Another significant point was that no country in the world leads official gas emission reporting of this type. It must be added that the work only referred to CH4 (without including CO2 emission). The estimated amount of CH4 emission from abandoned mines in the U.S in 2000 was 385 mln m3. b) United Kingdom This problem has been reported in United Kingdom for almost 30 years (Hall et al., 2006; Creedy, 1989). Almost 900 coal mines have been closed down and a gas hazard has been reported in 75 of them (Creedy, 1998). A gas hazard was connected with a person's death in the area of Northumberland and it resulted in the implementation of compulsory law regulations for gas measurement and classification. c) France In France, methane emission was detected coming from shallow goafs (Pokryszka et al., 2005) It was noticed that in the area of a children's playground, there was intensive methane emission (up to 85 cm3/min/m2). d) Germany In Germany the problem has been reported since 1976 (Eicker, 1987; Otto, 2010). Longterm research has indicated that when pressure falls, there is an increase in methane and carbon dioxide emission above abandoned shafts. Maximum concentration of CO2 measured in 1978 was up to 30%vol, and the total volume flow was up to 1000 m3/h. At the same time, oxygen concentration decreased to 5%vol. When considering methane drainage systems from closed mines, one can observe that methane emission has been decreasing in subsequent years. For example in 1980 the emission rate was 270 m3 CH4/h, and in 1983 was 50 m3 CH4/h. e) China Research into greenhouse gas emissions conducted by prof. Creedy (Creedy et al., 2003) stated that 50 coal mines out of a total number of 120 closed mines are a potential danger to the atmosphere. The average greenhouse gas emissions were computed at the level of 200 dm3/s and their annual emission was estimated as 4,4 * 106 Mg CO2, although one of the selected mines emitted about 420 mln m3 CH4 per year. Partial usage of methane drainage for energy purposes or partial flooding are recommended for emission prevention (Krause & Pokryszka, 2013). This statement contradicts conclusions drawn by J. Hall (Hall et al., 2006). He maintained the thesis that greenhouse gas emissions can be noticed even above flooded mines. f) Czech Republic The Upper Silesia coal basin is divided into the Polish and Czech parts. Czech closed many mines in the 90's and the problem of gas emission at the surface was detected at that time (Prokop, 2001; Novotny et al., 2001). As a result of methane migration to the surface in 1999, there was a methane explosion in one of the houses in the city of Ostrava and one person died. There were also many similar examples of methane or carbon dioxide presence in cellars, garages etc. g) Ukraine The most important cases of gas emission were noticed in the Stachanowskij area (Kasimov et al., 1999). According to research undertaken by Ukrainian authors, there were 73 cases of methane ignition and 3 cases of blackdamp in the houses. The total number of people injured by the presence of gas was 91. h) Australia In this region, research was carried out by L. Lunarzewski (Lunarzewski, 2009). The main research findings were: · Coal mine goafs in Australia have been classified in relation to the mining, hydrogeological and ownership conditions; · The amount of methane from coal mine goafs was estimated using emission decay curves and related mathematical formulae thus avoiding difficulties in identifying all gas sources and their magnitude; · The proposed coal mine goafs have been classified in relation to the case studies carried out on selected underground coal mines which defined eight various categories in relation to similar mining, gassy and geological conditions; · Where some typical data is lacking, site investigation may be required involving drilling, gas monitoring, water and gas pumping tests. i) Poland In the 90's in Poland, there were significant and dangerous examples of methane and carbon dioxide emissions from abandoned mines within The Upper and Lower Silesia coal basins (Kotarba, 2002; Szlazak et al., 2003). All coal mines in The Lower Silesia area were closed at once. The coal mines in The Upper part have been partly closed and that process is expected to continue in the future. The range of the restructuring process in Polish coal mining 1991-2008 is shown in Fig. 1. The number of active coal mines was reduced from 70 to 31, the amount of coal output was decreased from 140 to 83,4 mln Mg, and employment fell from 353 000 to 119000 people (Fig. 1). Fig. 1. The range of restructuring process in Polish coal mining 1991-2008 (WUG Report, 2009) In each case, a gas hazard was detected immediately after termination of mine ventilation. The results of research conducted in The Lower Silesia showed that main sources of methane and carbon dioxide migration were faults (46% of total number of cases), edge lines of shallow exploitation and shafts (about 30%), porphyry (about 15-20%) and outcrops (the rest). The maximum concentration of methane was 25,7%vol and the maximum concentration of carbon dioxide was 10,5%vol (Krzystolik & Kobiela, 2002; Czaja, 2011). Abandoned shafts, drifts, gaps and faults could be considered as possible sources of gas emissions. The kinds of gas flow are listed below (Grzybek, 2012; Kulczycki & Grzybek, 1999; Wrona et al., 2014): Diffusive caused by a gas concentration gradient which occurs between different elements of the coal matrix. Filter through a porous medium caused by gas pressure balancing in the gaps. Flow to the surface is the effect of pressure difference. Convective caused by the buoyancy phenomenon, including different densities of gases in underground conditions. Hydraulic taking place in empty excavations, drilling holes and gaps which have connections with the surface which are under the influence of external forces (atmospheric pressure changes and increase of underground water level). According to Table 1 in the Upper Silesia region, there are 24 shafts which are left for water pumping. They should be considered as sources of greenhouse gases emission with possible hydraulic flow. TABLE 1 The number of closed shafts and their total depth in Polish coal mines after 1990 (Czaja, 2011; WUG Report, 2009) No. Group of mines Closed shafts The number Summary depth[m] The coal mines belong to the coal company Kompania Wglowa S.A. (Upper Silesia) Other coal mines (Upper Silesia) Former independent mines (Upper Silesia) The coal mines in Lower Silesia Shafts which are left for underground water pumping Total: 34 339,5 16 135,5 55 947,0 35 550,0 13102,0 155074,0 According to the state of the art (Wrona, 2010), the process of gas flow through a shaft depends on: a) the gas bearing capacity of a seam (in the case of CH4 emission) (Grzybek, 2012), b) the goafs oxygen contact area, c) the geological structure, including height of overburden, d) the underground water level increase and CO2 saturation in water, g) the atmospheric pressure changes (Wrona, 2005). 2. The Measurements The measurements were based on Polish Standard PN-EN 15259 ,,Jako powietrza. Pomiary ze ródel stacjonarnych, Wymagania dotyczce odcinków pomiarowych, miejsc pomiaru, celu i planu pomiaru oraz sprawozdania z pomiaru" (Air quality. Measurement of stationary source emissions. Requirements for measurement sections and sites and for the measurement objective, plan and report) (PN-EN 15259). The plan of the measurements was based on the above mentioned standard, on Namieniak's Measuring Guide Book (Namieniak et al., 1995) and on (Górka et al., 2000) The maps of carbon dioxide concentration around the shaft were developed using Surfer Software and PN-Z-04008-02:1984 ,,Ochrona czystoci powietrza. Pobieranie próbek. Wytyczne ogólne pobierania próbek powietrza atmosferycznego (imisja)" (PN-Z-04008-02:1984) and (Juda & Chróciel, 1974). 2.1. The Measurement Location The closed shaft Gliwice II was selected as a working area for future investigation (Fig. 2). It is situated in the city of Gliwice, Bojkowska street 37. The shaft is left for water pumping purposes and belongs to Centralny Zaklad Odwadniania Kopal w Czeladzi (Central Plant of Water Pumping in Czelad). The area is presented in Fig. 2. Fig. 2. The area of Gliwice II shaft. 1 the building of Higher School of Economy in Gliwice, 2 two symmetrical points of emission, 3 pipelines for water pumps, 4 the outlet of the fan no. 1, 5 the outlet of the fan no. 2 2.2. The Methodology The process is considered as constant with different and variable factors (air pressure and temperature) influencing it. Four points were carried out for "in situ" emission measurements (Namieniak et al., 1995) during preliminary surveys (points no 2 (having 2 outlets), 4 and 5). The overview is presented in Fig. 2 and 3). Point 2 (Fig. 3) consists of two symmetrical outlets with dimensions 0,23 m × 0,68 m. The cross-section area of each outlet is 0,1564 m2. a) Point 4 is the outlet of the fan no.1 which allows for underground inspections. The crosssectional area equals 0,125 m2. b) Point 5 is the outlet of the fan no.1 which is also dedicated to ventilation purposes in the lower parts of the shaft. The cross- sectional area equals 0,125 m2. It was stated that there is significant concentration of carbon dioxide and the gas concentration is constant in the profile. As a result continuous traverse method to establish average velocity was selected (Waclawik, 2010). Measurements were planned each month, including collection of meteorological data. Fig. 3. Measuring mesh including location of measuring points no. 2, 4 and 5 2.3.The Instruments The following devices have been put into operation: a portable detector MultiRAE Plus, an Assmann's psychrometer, a digital anemometer AS (Fig. 4]), a gas detector WG-2M. General meteorological data has been collected from Central Mining Institute's meteorological station [internet source 1]. Pressure changes above the shaft have been measured with a portable barometer Barolux. Fig. 4. Air velocity measurements at point no. 2 3. The Results and The Discussion The results are divided into two sections: the first refers to carbon dioxide emission assessment and the second gives information about gas concentration above the shaft. 3.1. The emission Selected results from 02.2014 to 05.2014 are given in Table 2. The maximal value of CO2 emission was observed on 28.02.2014 at 10:36. It was 2,69 m3/min. The pressure fall lasted for 20 hours with average baric tendency 0,4 hPa/1h. The difference in temperature between gas and atmosphere was 5,4°C. On 14.03.2014 average baric tendency was higher than on 28.02.2014. It was 0,53 hPa/h, however, the emission rate was lower. It was 1,66 m3/min at 16:42. The reasons for this is that there was no difference in gas and atmospheric temperature (td = 0,1°C) and a shorter pressure fall time (8 h 12'). On 21.05.2014, the average baric tendency was 0,2 hPa and the pressure fall lasted for 5 h. The dry bulb temperature difference was 8,9°C. The emission was 0,36 m3/min at 15:00. The last test result example obtained during the pressure fall is from 23.05.2014. The baric tendency was low 0,16 hPa/h, it lasted for 12 h and the dry bulb temperature difference TABLE 2 The results of CO2 measurements from the points no. 2, 4 and 5 Date Hour VCO2 point 2 [m3/min] bt [hPa/1h] VCO2 point 4 [m3/min] VCO2 point 5 [m3/min] Total CO2 emission [m3/min] Pressure at the beginning of fall or increase [hPa] Pressure during the measurement [hPa] Time from the beginning of fall or increase td gasatmosphere [°C] td the result [°C] 28.02.2014 987,0 982,6 0,53 980,0 972,0 0,4 20h 8h12' 11,2- 5,2 12,4 7,0 12,0-12,1 6,0 5,4 0,1 9:15 10:36 10:20 15:22 16:42 10:00 15:00 982,7 981,7 0,2 0,08 977,6 975,7 0,16 1,13 1,42 0,34 0,58 0,73 0,11 0,24 1,98 2,69 0,80 1,61 1,66 0,21 0,36 5h 13,8-16,8 14,8-23,1 15,3-24,2 12h 14,2-24,3 3,0 8,3 8,9 10,1 0,08 12:00 0,0 0,15 0,15 978,5 + -- 14,9-27,1 -- 12,2 -- 0,0 0,28 0,34 0,14 0,45 0,39 0,05 0,07 -- (out of range) -- (out of range) 0,0 0,57 0,93 0,32 0,58 0,54 0,05 0,05 -- (out of range) -- (out of range) 0,0 bt -- average baric tendency, average change of pressure during 1h, hPa/1h, td -- dry bulb temperature difference, °C. TABLE 3 The results of CO2 measurements from the points no. 2, 4 and 5 including air velocities and CO2 concentration Date Hour w VCO2 point 2 point 2 [m3/min] [m/s] VCO2 point 4 [m3/min] VCO2 point 5 [m3/min] CO2 concentration point 2 [%vol.] w point 4 [m/s] w point 5 [m/s] CO2 concentration point 4 [%vol.] CO2 concentration point 5 [%vol.] Total CO2 emission [m3/min] 9:15 10:36 10:20 15:22 16:42 10:00 15:00 0,90 -- 0,30 -- 1,13 1,42 0,34 0,58 0,73 0,11 0,24 2,42 2,45 1,30 1,7 2,27 1,15 1,39 5,00 6,20 2,80 3,65 3,45 1,10 1,90 1,10 1,20 1,13 1,65 1,66 0,90 1,10 3,50 3,80 1,70 3,65 3,20 0,80 0,90 1,60 2,13 1,60 1,95 1,92 0,85 0,70 4,80 5,80 2,70 3,90 3,70 0,80 1,00 0,35 1,98 2,69 0,80 1,61 1,66 0,21 0,36 0,08 0,08 1,06 12:00 0,06 0,15 1,20 1,50 -- 0,90 0,06 -- 0,91 0,06 0,15 0,0 0,0 0,28 0,34 0,14 0,45 0,39 0,05 0,07 -- (*lack of data) -- (*lack of data) 0,0 0,57 0,93 0,32 0,58 0,54 0,05 0,05 -- (*lack of data) -- (*lack of data) 0,0 * unauthenticated data obtained with application of a vane anemometer, rejected for further analysis was 12,2°C. The total emission of CO2 was 0,15 m3/min at 12:00. However, it was not possible to detect CO2 emissions. Obtained data was unauthenticated and it was rejected for further considerations. On 30.05.2014 there was a pressure increase. No gas emission from the shaft was detected. It was observed that there was no gas flow into the air nor flow in the opposite direction. The results obtained contradict the German statement (Eicker, 1987) that gas emission from a shaft has a linear relation only to the pressure value and they match the results obtained during previous research undertaken within The Upper Silesia Coal Basin, e.g. (Sulkowski & Wrona, 2006). When considering CO2 it should be observed that the emission is a function (equation 1) of the following factors: the average baric tendency, (bt), the time of pressure fall, (t), the difference of gas ambient densities, () (which at first is represented by the dry bulb temperature difference and is followed by the individual gas constant etc. V = f(bt, t, ) (1) The significance of several factors should be further investigated. Using the results obtained, it is possible to make general estimations of possible carbon dioxide emissions from the shaft "Gliwice II' that could be observed during one day with meteorological conditions as described on 28.02.2014. According to Table 2 measured maximal rate of carbon dioxide emission is 2,69 m3/min. This result can be different from real values, although it gives general knowledge about the range of the emission and amount of emitted green house gas to the atmosphere. Knowing average density of carbon dioxide (1,9 kg/m3) it gives rate of emission equals 5,11 kgCO2 /min. This value should be documented and reported within frames of air protection programs with application of gas manual and automatic monitoring systems, e.g. (Wasilewski, 2008). 3.2.Carbon dioxide concentration map The following research has never been done before in Poland and the author doesn't know of any similar results following abandoned (closed) coal mine shafts.. According to the latest (in situ) experiments, the main aim of the measurements was to obtain preliminary results and develop a possible methodology for future analysis. The measurements were taken at ground level (0 m) and 1m level moving from point no. 1 to point no. D. A gas detector was left at each point for two minutes, the data login in the detector was set for 30 second intervals which gave a total of 4 results for the point. Then the value was averaged. The maps were produced on Surfer Software. The example of carbon dioxide concentration around selected shafts from 21.05.2014 is presented in Figure 5. The wind was from East direction, however during the measurements (9:00-12:00) the wind speed did not exceed 0,8 m/s. On the left side of figure 5, there is a CO2 concentration map which represents gas isolines at 0m level. Higher values of CO2 concentration are clearly visible in the area around point no. 2 (according to Fig. 3). Points 4 and 5 are represented by gas isolines 1,2%vol and 1,0%vol in the Fig. 5. The example of CO2 concentration in the selected area. On the left at the surface (level of the ground 0 m), on the right at 1m. Measurements were taken on 21.05.2014. The results are presented in %vol unit. Axis units are meters right-upper part of the figure. On the right side of Figure 5 the distribution of the gas isolines at the level of 1m is different. Although three points of emission can easily be detected by the gas isolines above point 2 and gas isolines in the right-upper part 0,16%vol. It can be observed that CO2 at the 1 m level is diluted but still noticeable. On 21.05.2014 the background level of CO2 was 600 ppm (0,06%vol) which leads to the conclusion that the area of higher gas concentration is detected even up to 8 m from the source of emission. 4. Conclusions 1. Each abandoned or closed coal mine shaft should be considered as a possible source of greenhouse gas emissions. The results presented in the article prove that carbon dioxide emission could be significant. Literature overview indicates that in other cases methane should be expected, too. 2. The maximal detected CO2 emission was 2,69 m3/min. Including carbon dioxide density it equals 5,11 kgCO2/min. According to USA research since 2004 (Report, 2004), no country in the world leads official gas emission reporting of this type. The results presented above show that the current situation should change and these subjects should be covered by regular monitoring and reporting in national air protection programmes. 3. Carbon dioxide emission can create local gas hazards above an abandoned or closed shaft. Maps of CO2 isolines at levels of 0 m and 1m show that the gas could be detected up to 8 m from the source of emission. It leads to the conclusion that each site of that type should have restricted access. Acknowledgments This research was carried out during the national project: "Eko-sta" no. (Ekosta/19/2014), titled: Klasyfikacja zlikwidowanych szybów kopal wgla kamiennego pod ktem emisji gazów cieplarnianych. Appreciations for GGS-PROJEKT Pracownia geologii i ochrony rodowiska Lukasz Gsior and for Mr. Dawid Malek for support during the project and for Mr. David Hudson for English correction.
Archives of Mining Sciences – de Gruyter
Published: Sep 1, 2016