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Fire Prevention in Coal Waste Dumps
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CHAPTER 13
Fire Prevention in Coal Waste Dumps: Exemplified by the Rymer Cones, Upper Silesian Coal Basin, Poland
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CHAPTER CONTENTS
13.1 Coal Waste Dump Fires Introduction Fire Prevention 13.2 Technology for Fire Prevention and Reclamation Introduction Rymer Cones Dump 13.3 Monitoring Rymer Cones and Implementing Fire Mitigation Introduction Rymer Cone No. 1 in a coal waste dump, Upper Silesian Coal Basin, Poland. The height of the cone is 23 m. The dump includes two other cones (not visible here) that were combined during redevelopment. Photo by Adam Tabor, 2007.
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Coal and Peat Fires: A Global Perspective Edited by Glenn B. Stracher, Anupma Prakash and Ellina V. Sokol Copyright © 2015 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/B978-0-444-59509-6.00013-2
13.1 Coal Waste Dump Fires Magdalena Misz-Kennan Mariusz Gardocki Adam Tabor
Photos by Adam Tabor, 2007 (top) and 2008.
Smoke exhaled from the SE part of the Rymer Cones waste dump and burnt plants at the dump. The horizontal fields of view are 40 m (top) and 3 m.
Introduction The problem of fires in coal waste dumps has existed throughout the history of organized coal mining. Dumps adjacent to coal mines were typically formed as cones from the beginning of the 1890s. In building the dumps, old techniques were used, which actually promoted the self-heating processes leading to endogenic fires. The processes of self-heating of coal waste has been investigated for many years (Beamish et al., 2001; Brooks et al., 1988; Clemens and Matheson, 1996; Hull et al., 1997; Itay et al., 1989; Kaji et al., 1985; Krishnaswamy et al., 1996a,b; Pone et al., 2007; Wang et al., 2003a,b). They are still not fully explained, although a number of hypotheses have been proposed. At present, it is believed that the oxidation of organic matter of coal waste is the precursor to the ignition of the waste (Krishnaswamy et al., 1996a; Lu et al., 2004; Singh et al., 2007). This hypothesis is based on the complex phenomenon of the sorption of oxygen in coal in contact with atmospheric air. In the 1980s, some rules were developed for the construction of coal waste dumps so as to inhibit fires. These rules were based on the widely accepted premise that self-heating and fire are possible only when three conditions are fulfilled at the same time (Urbański, 1983; Szafer et al., 1994; Tabor, 1999, 2002; Barosz, unpublished data; Pone et al., 2007). First, the deposited waste material must contain some combustible coaly material of the appropriate activity. The content of this coaly matter is variable, usually 5–20%, depending on the type of coaly matter (petrographic composition and coal rank), the technology of coal exploitation, and the coal enrichment processes. Second, there must be access to air into the interior of the dump, which must be conical and be composed of loose material. Third, there must be the possibility of heat accumulation within the dump. The exclusion of any one of these conditions will make the occurrence of endogenic fire unlikely if not impossible.
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Fire Prevention In the past, fires in coal waste dumps were a common phenomenon. Almost all dumps (typically cones) were subject to self-heating and combustion. Material deposited in these dumps was usually completely transformed. Dump combustion is a long-term process. Large dumps in which several million cubic meters of waste material may have been deposited will maintain high temperatures for a long time, even after completely burning out. During the extraction of burnt-out waste material for building roads, dumps that had not shown any evident thermal activity on the surface were discovered to have interior temperatures exceeding 400 °C. Such old and still thermally active dumps are sources of air and water pollutants resulting from the transformation of organic and mineral matter in the waste. The efficient and complete extinction of the fires is possible only by digging trenches or completely dismantling the dumps. New coal waste dumps should fulfill the fire prevention conditions. In these, the waste material is deposited in 0.5–1.0 m thick layers and compacted with vibrating rolls, slopes are properly formed, and the dumps are periodically monitored. In this way, the danger of fire is minimized. Elimination of air access into the interior of the dump is accomplished through good sealing. Any rise in temperature that occurs will be limited and will not lead to ignition. A temperature below 60 °C is considered safe. Higher temperatures are dangerous. The curve of temperature increase rises sharply to reach the temperature of ignition for bituminous coal at about 200 °C (Sawicki, 2004). A different situation can be observed when a new dump is located in contact with an old, burnt-out dump that is still thermally active. An old dump, partly or completely burnt out, is usually cold outside, hot inside, and in thermal equilibrium with its surroundings. The heating limit lies somewhere inside the old dump. The addition of fresh waste to the side of the dump causes disruption of the thermal equilibrium; the heating limit moves toward the outer parts of the old dump. In some unfavorable situations, it can reach the recently deposited material, and if the temperature exceeds 60 °C, it can rise further very rapidly to initiate endogenic fires in the new material.
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13.2 Technology for Fire Prevention and Reclamation
Photo by Adam Tabor, 2007.
Burnt plants on the southern slope of the Rymer Cones waste dump. The city of Rymer is in the background.
Introduction New fire prevention techniques utilize trenches filled with an inert incombustible material such as clay or fly ash. The purpose of such techniques is to prevent the transfer of fire from heated parts of the old dump into unaffected parts that are composed of new waste. This solution was proposed by the Central Mining Institute in Katowice (Poland) and was used for the first time when the older parts of the Rymer Cones in Rybnik (Upper Silesian Coal Basin, Poland) were surrounded by new waste material.
Rymer Cones Dump The Rymer Cones were formed in the early 1900s as three cones some 60–65 m in height located close to the Rymer Coal Mine (now closed) and, incidentally, very close to blocks of flats in the district of Rybnik town (Figures 13.2.1 and 13.2.2). At present, the dump occupies an area of 13 ha and its capacity is 2 million cubic meters. Over many years, these cones were almost completely burnt out. The thermal activity of varying intensity was a great environmental nuisance for people living in the nearby blocks of flats. At the end of the 1980s, an attempt was made to reclaim the dump. A new method to extinguish the fires was developed based on cutting off the access of air into the dump interior. The old waste dump was surrounded by new waste rocks using appropriate compaction and sealing material. It was planned that the cones were to be lowered and combined into one feature and its top prepared for sealing. Cone No. 1 was to remain as a view point. It was also planned that the border between the old and new material be surrounded by a moat (Figure 13.2.3) filled with inert incombustible material, mostly clays and fly ash from the power station. In 1995–1999, the reclamation works were carried out (Figures 13.2.3–13.2.7). The dump was rebuilt and cone No. 1 was retained (Figure 13.2.8). The highest point of the dump is 323 m above sea level. The cone showed no signs of heating. The formation of the top of the dump was a difficult undertaking due to the presence of numerous very large sinters in the former cone Nos 2 and 3 (Figures 13.2.3, 13.2.4 and 13.2.7). This was the end of the first stage to extinguish the fires in the Rymer Cones dump.
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Figure 13.2.1. Rymer Cones Nos 2 and 3 in 1996. Photo by Adam Tabor, 1996.
Figure 13.2.2. The beginning of the enclosure of Rymer Cone No. 2. Photo by Adam Tabor, 1996.
Figure 13.2.3. Formation of the moat filled with fly ash and clay surrounding Rymer Cone No. 3. The width of the road is about 5 m. Photo by Adam Tabor, 1996.
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Figure 13.2.4. Formation of the moat filled with fly ash surrounding Rymer Cone No. 3. The vertical field of view is about 35 m. Photo by Adam Tabor, 1996.
Figure 13.2.5. Formation of the moat filled with fly ash surrounding Rymer Cones Nos 2 and 3. Photo by Adam Tabor, 1996.
Figure 13.2.6. The beginning of the enclosure of Rymer Cone No. 1. The width of the road is about 5 m. Photo by Adam Tabor, 1996.
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Figure 13.2.7. Advanced works on the enclosure of Rymer Cone No. 3. Photo by Adam Tabor, 1996.
Figure 13.2.8. A general view from Wodzisławska Street of the eastern part of the Rymer Cones dump after reclamation. Photo by Adam Tabor, 2001.
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13.3 Monitoring Rymer Cones and Implementing Fire Mitigation
Photo by Adam Tabor, 2007.
SE part of the Rymer Cones waste dump, locally covered with fly ash (gray blocks). The vertical field of view is 10 m.
Introduction The first signs of reheating in the dump appeared in 2000. The former authorities at the mine implemented additional sealing of the dump. The hot parts of the dump were covered with concrete panels and fly ash making a concrete-like cover (Figures 13.3.1–13.3.4). These actions proved sufficient only for a short period. Cracks appeared in the new cover. The area of heating and combustion spread, initially in the higher parts of the western and eastern parts of the dump (Figures 13.3.5 and 13.3.6) and later at the top (Figures 13.3.7 and 13.3.8) and in the southern part. The signs of heating were most evident in the western part as this part is most exposed to the dominant winds from the west. The signs of heating were best seen during winter after snowfalls (Figures 13.3.9–13.3.17).
Figure 13.3.1. Western side of the Rymer Cones sealed with concrete panels and fly ash after the first signs of heating after reclamation of the dump. The height of the trees is 5 m. Photo by Adam Tabor, 2002.
Figure 13.3.2. Eastern side of the dump covered by concrete panels and sealed with fly ash, as it appears today. The height of the trees is 5 m. Photo by Adam Tabor, 2002.
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Figure 13.3.3. The western side of the dump covered with concrete panels and sealed with fly ash. The height of the poles is about 0.5 m, and they are used to support the concrete panels. Photo by Adam Tabor, 2002.
Figure 13.3.4. The western side of the dump covered with concrete panels and sealed with fly ash, showing the border between the enclosed and unenclosed parts of the dump. The height of the poles is 0.5 m, and they are used to support the concrete panels. Photo by Adam Tabor, 2002.
Figure 13.3.5. Visible heating on the SW slope, prior to redevelopment. The width of the road is 6 m. Photo by Adam Tabor, 2002.
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Figure 13.3.6. Burnt plants on the SW slope of the dump. The height of the pole is 1 m. Such poles are used to support concrete panels. Photo by Adam Tabor, 2004.
Figure 13.3.7. Gas emissions and cracks in fly ash covering the top of the dump. Photo by Adam Tabor, 2004.
Figure 13.3.8. View of the remains of Rymer Cone No. 1 and the top of the dump covered with a 1 m layer of fly ash. The height of the trees is 5 m. Photo by Adam Tabor, 2006.
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Figure 13.3.9. View of the western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2003.
Figure 13.3.10. The central part of the western side of the dump prior to redevelopment. The height of the trees is 5 m. Photo by Adam Tabor, 2003.
Figure 13.3.11. Hot spot without snow, on the western slope below the concrete panels and fly ash cover. The vertical field of view is 50 m. Photo by Adam Tabor, 2004.
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Figure 13.3.12. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The height of the trees is 5 m. Photo by Adam Tabor, 2006.
Figure 13.3.13. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The horizontal field of view is about 25 m. Photo by Adam Tabor, 2006.
Figure 13.3.14. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2006.
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Figure 13.3.15. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2006.
Figure 13.3.16. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The remains of Rymer Cone No. 1 are visible. Photo by Adam Tabor, 2006.
Figure 13.3.17. Southern side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The remains of Rymer Cone No. 1 are visible. Photo by Adam Tabor, 2006.
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Monitoring and Mitigation The whole dump was and is regularly monitored with regard to its thermal state. A few tens of measurement points were located in places where indications of heating were observed on the surface of the dump. Monthly measurements of CO, CO2, and O2 contents are carried out at the depth of 0.8–1.0 m and of temperature at the same depth and on the surface, following a methodology elaborated at the Central Mining Institute in Katowice. The experience gained from similar monthly monitoring carried out in the dumps of Marcel, Anna, Chwałowice, and Rydułtowy coal mines led to modifications in fire prevention methods in these and the Rymer Cones dumps— dumps where there is the possibility of heat transfer between old and new waste material. Further observations and monitoring in recent years has changed opinions. Based on recent experience, it was concluded that the problem of the fire prevention centered on the transfer of heat within the dump. This resulted in further changes in ways of fire prevention, new technologies, and the formation of new dumps abutting old dumps. The most basic element in the changes implemented in the Rymer Cones dumps was the excavation of the heated sites to cool them. These works were undertaken in 2004 and continue to the present day with positive results (Figures 13.3.18–13.3.38). The disadvantage of these excavations is the formation of dust, which leads to negative reactions from the people living in the nearby blocks of flats. The final results of these excavations was liquidation of the fire spots and the relatively rapid (several hours to several days) cooling of the adjacent areas in the dump (Figures 13.3.39–13.3.43). One of the undertakings was the removal of the concrete-like cover in the western part of the dump. The slope of the dump was made less steep. The result of the rebuilding of the western and southern parts of the dump was elimination of the active fire spots. Unfortunately, the entire western site of the dump is still heated as shown by the brown spots of venting hydrocarbons on the dump surface (Figures 13.3.44–13.3.47) as well as the steaming of the dump surface after rain. Such heating is relatively minor with temperatures on the surface higher by 10–20 °C than
Figure 13.3.18. The first excavations on the western slope of the dump, to eliminate the hot spots shown in Figures 13.3.9 and 13.3.10. Photo by Adam Tabor, 2004.
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Figure 13.3.19. The first excavated hot spot in the SW corner of the dump. The trenches shown are from where Figure 13.3.7 was taken. The height of the poles is about 1 m, and they are used to support concrete panels. Photo by Adam Tabor, 2004.
Figure 13.3.20. Western part of the dump and excavation of the heated area in the lower part of the dump. The length of the poles is about 1 m, and they are used to support concrete panels. Photo by Adam Tabor, 2006.
Figure 13.3.21. Western part of the dump and excavation of the heated area in the lower part of the dump near the pipes. The diameter of the pipes is 0.8 m. They are used to transport hot water from the Chwałowice Coal Mine to homes in Rymer, a district of Rybnik town. Heat energy from the water is then used to heat apartments in Rymer. Photo by Adam Tabor, 2006.
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Figure 13.3.22. Southern part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.23. A view of the SE part of the dump during reclamation. Photo by Adam Tabor, 2009.
Figure 13.3.24. SE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.25. SE part of the dump. The horizontal field of view is 25 m. Photo by Adam Tabor, 2009.
Figure 13.3.26. SE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.27. SE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.28. South-south east (SSE) part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.29. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.30. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.31. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.32. SSE part of the dump. The gray blocks on the right are the remains of a fly ash cover. The horizontal field of view is 20 m. Photo by Adam Tabor, 2009.
Figure 13.3.33. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.34. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.35. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.36. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.37. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.38. SSE part of the dump. The horizontal field of view is 10 m. Photo by Adam Tabor, 2009.
Figure 13.3.39. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.40. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.41. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.42. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.43. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.44. Brown staining from hydrocarbons on the western side of the dump. Photo by Adam Tabor, 2006.
Figure 13.3.45. Brown staining from hydrocarbons on the southern side of the dump. Photo by Adam Tabor, 2006.
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Figure 13.3.46. Brown staining from hydrocarbons on the western side of the dump. Photo by Adam Tabor, 2006.
Figure 13.3.47. Brown staining from hydrocarbons on the southern side of the dump. Photo by Adam Tabor, 2006. those of the surrounding air. The western slope is mostly covered by plants throughout the year. The elevated temperatures, and the snowfall and rainfall, create a microclimate. During springtime and summertime, plant growth there is especially luxuriant with some plants reaching sizes much greater than normal (Figures 13.3.48–13.3.61). The result of these remedial actions was a reduction of the influence of the Rymer Cones dump on the environment. The whole dump is still heated. Its interior, mostly completely burnt out, still maintains high temperatures. Drillings carried out on the top of the dump in 2007 showed temperatures of about 300 °C at the outlet of the drill hole. As a result of these high interior temperatures, areas of smoking and gas exhalation have reappeared in various places on the dump (Figures 13.3.62–13.3.64). The thermally active sites are being excavated and cooled now. The eastern side of the dumps is interesting (Figures 13.3.65–13.3.76). On this leeward side, the upper parts of the dump have shown elevated temperatures at an almost constant level over several years. This part of the dump was not rebuilt. At the depth of about 1 m, the temperature is 65–75 °C and the CO content is 0.02 vol.%. Although dried out in several places, most of the slope is covered by low-level, evergreen plants. This slope is a nesting site for partridge and pheasant, and rabbits are common. In the past several months, the heating has moved into lower parts (Figures 13.3.62–13.3.64). As mentioned in the beginning, the rebuilding of the three cones proved very difficult due to the presence of largesize sinters similar to rock towers in the upper part of the cones. The crushing of the sinters required a lot of effort, which included even the use of explosives. Cones Nos 2 and 3 were leveled by about 20 m. The highest parts of the cones were moderately heated. After preliminary flattening, the top was leveled using waste rocks from the current coal mining and with humus soil before being sown with grass. After the reclamation of the dump, the first signs of heating appeared in 2000. The top was then covered with a layer of fly ash that in places exceeded 1 m in thickness. The present experiences show that this was a mistake. It is impossible to completely seal a dump, and the screens of clay and fly ash did not prevent the transfer of heat. As a result, fire spots appeared in the newly formed surface, cracks developed, and gas and smoke emissions of varying
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Figure 13.3.48. Plants migrating onto the western side of the dump. The height of the trees near the top of the cone in the background is 5 m. Photo by Adam Tabor, 2006.
Figure 13.3.49. Plants migrating onto the western side of the dump. The height of the plants is 0.7 m. Photo by Adam Tabor, 2006.
Figure 13.3.50. Plants migrating onto the western side of the dump. Photo by Adam Tabor, 2006.
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Figure 13.3.51. Plants migrating onto the western side of the dump. The height of the plants is 0.7 m. Photo by Adam Tabor, 2006.
Figure 13.3.52. Plants migrating onto the southern part of the western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.53. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
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Figure 13.3.54. Plants migrating onto the southern part of the western side of the dump. The horizontal field of view is 20 m. Photo by Adam Tabor, 2008.
Figure 13.3.55. The western side of the dump below the remains of Rymer Cone No. 1. Photo by Adam Tabor, 2008.
Figure 13.3.56. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
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Figure 13.3.57. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
Figure 13.3.58. Abundant plants on the northern part of the western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.59. Abundant plants on the southwestern side of the dump. Photo by Adam Tabor, 2008.
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Figure 13.3.60. The western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.61. The western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.62. The southern part of the dump during reclamation work. Photo by Adam Tabor, 2009.
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Figure 13.3.63. The recent hot spot in the eastern part of the dump. The width of the road is 5 m. Photo by Adam Tabor, 2009.
Figure 13.3.64. The recent hot spot in the eastern part of the dump. The horizontal field of view is 4 m. Photo by Adam Tabor, 2009.
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Figure 13.3.65. Concrete panels and fly ash in the eastern part of the dump. Temperatures have remained constant (75–80 °C at 1 m depth) here for many years. The height of the poles is about 0.5 m, and they are used to support concrete panels. Photo by Adam Tabor, 2001.
Figure 13.3.66. Concrete panels and fly ash on the eastern side of the dump, below Rymer Cone No. 1. Photo by Adam Tabor, 2002.
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Figure 13.3.67. Concrete panels and fly ash on the eastern side of the dump, below Rymer Cone No. 1. The horizontal field of view is 10 m. Photo by Adam Tabor, 2002.
Figure 13.3.68. View of the southern part of the dump, from the eastern slope. Photo by Adam Tabor, 2002.
Figure 13.3.69. The east-south east (ESE) part of the dump. Photo by Adam Tabor, 2003.
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Figure 13.3.70. The ESE slope of the dump. The horizontal field of view is 2 m. Photo by Adam Tabor, 2006.
Figure 13.3.71. The ESE part of the dump. The same area as in Figure 13.3.70. Photo by Adam Tabor, 2006.
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Figure 13.3.72. The eastern slope of the dump. The horizontal field of view is 2 m. Photo by Adam Tabor, 2006.
Figure 13.3.73. Camomile growing on the eastern slope of the dump. Photo by Adam Tabor, 2008.
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Figure 13.3.74. Fly ash and the remains of concrete panels on the eastern slope of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.75. Fly ash and the remains of concrete panels on the eastern slope of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.76. Fly ash and the remains of concrete panels on the eastern slope of the dump, below Rymer Cone No. 1. The height of the trees on the cone in the background is 5 m. Photo by Adam Tabor, 2008.
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intensity occurred (Figures 13.3.7 and 13.3.8). However, with the passage of time, the intensity of the heating in the upper part of the dump decreased and, now, steam and smoke emissions are to be seen only in places. The top of the dump is now covered by plants that migrated naturally into the dump (Figures 13.3.77 and 13.3.78).
Figure 13.3.77. The top of the dump covered with fly ash and a view of the remains of Rymer Cone No. 1. Photo by Adam Tabor, 2006.
Figure 13.3.78. A part of the top of the dump with the remains of Rymer Cone No. 1. The height of the trees on the cone is 5 m. Photo by Adam Tabor, 2008.
Conclusions The future of the Rymer Cones dumps depends on the future decisions of the owner of the dump—currently the coal company (Kompania Węglowa S.A.). The entire dump contains about 2 million cubic meters of partly burntout waste material with potential for use as aggregate. Dismantling of the whole reflects the necessity to maintain standards of environmental protection, mostly with regard to dust formation, which is impossible to avoid. However, the nearby blocks of flats, the necessity for complete reclamation of the dump after possible exploitation as aggregate, and high indirect costs make dismantling impossible at present. The dump interiors are heated, and there is a periodic necessity to extinguish active fire sites. A good solution would be to open the top of the dump to lower the temperature. This relatively easy means of cooling would inhibit the migration of hot spots within the dump and limit or even eliminate the thermal activity on the slope of the dump.
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Important Terms coal waste combustion Rymer Coal Mine Rymer Cones self-heating
References Barosz, S., unpublished data. Technical, economical and environmental conditions of management of coal waste dumps using the mines from the Rybnik Coal District as examples (in Polish). Ph.D., Academy of Mining and Metallurgy in Cracow, 221 p. Beamish, B.B., Barakat, M.A., George, J.D.St, 2001. Spontaneous-combustion propensity of New Zealand coals under adiabatic conditions. International Journal of Coal Geology 45, 217–224. Brooks, K., Svanas, N., Glasser, D., 1988. Evaluating the risk of spontaneous combustion in coal stockpiles. Fuel 67, 651–656. Clemens, A.H., Matheson, T.W., 1996. The role of moisture in the self-heating of low-rank coals. Fuel 75, 891–895. Hull, A.S., Lanthier, J.L., Chen, Z., Agarwal, P.K., 1997. The role of the diffusion of oxygen and radiation on the spontaneous combustibility of a coal pile in confined storage. Combustion and Flame 110, 479–493. Itay, M., Hill, C., Glasser, D., 1989. A study of the low temperature oxidation of coal. Fuel Processing Technology 21, 81–97. Kaji, R., Hishinuma, Y., Nakamura, Y., 1985. Low temperature oxidation of coals: effect of pore structure and coal composition. Fuel 64, 297–302. Krishnaswamy, S., Bhat, S., Gunn, R.D., Agarwal, P.K., 1996a. Low-temperature oxidation of coal. 1. A singleparticle reaction–diffusion model. Fuel 75, 333–343. Krishnaswamy, S., Agarwal, P.K., Gunn, R.D., 1996b. Low-temperature oxidation of coal. 3. Modelling spontaneous combustion in coal stockpiles. Fuel 75, 353–362. Lu, P., Liao, G.X., Sun, J.H., Li, P.D., 2004. Experimental research on index gas of the coal spontaneous at lowtemperature stage. Journal of Loss Prevention in the Process Industries 17, 243–247. Pone, J.D.N., Hein, K.A.A., Stracher, G.B., Annegarn, H.J., Finkelman, R.B., Blake, D.R., McCormack, J.K., Schroeder, P., 2007. The spontaneous combustion of coal and its by-products in the Witbank and Sasolburg coalfields of South Africa. International Journal of Coal Geology 72, 124–140. Sawicki, T., 2004. Spontaneous combustion in stock piles as the cause of fire. Karbo 1, 56–59 (in Polish). Singh, A.K., Singh, R.V.K., Singh, M., Chandra, H., Shukla, N.K., 2007. Mine fire gas indices and their application to Indian underground coal mine fires. International Journal of Coal Geology 69, 192–204. Szafer, M., Urbański, H., Tabor, A., 1994. Rules for the Re-cultivation of Coal Waste Dumps Using Modern Techniques (in Polish). Central Mining Institute, Katowice 63 p. Tabor, A., 1999. Technical–ecological problems in coal waste collection (in Polish): IV Conference Conditions in the local plans for land development in towns and communes of the Rybnik Coal Area, Rybnik, pp. 195–202. Urbański, J., 1983. Technical Re-cultivation of Mine Waste Dumps with Particular Reference to Fire Protection. Training Materials (in Polish). The Association of Mining Engineers and Technics, Katowice 61 p. Wang, H., Dlugogorski, B.Z., Kennedy, E.M., 2003a. Coal oxidation in low temperatures: oxygen consumption, reaction mechanism and kinetic modeling. Progress in Energy and Combustion Science 29, 487–513. Wang, H., Dlugogorski, B.Z., Kennedy, E.M., 2003b. Analysis of the mechanism of the low-temperature oxidation of coal. Combustion and Flame 134, 107–117.
CHAPTER 13
Fire Prevention in Coal Waste Dumps: Exemplified by the Rymer Cones, Upper Silesian Coal Basin, Poland
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CHAPTER CONTENTS
13.1 Coal Waste Dump Fires Introduction Fire Prevention 13.2 Technology for Fire Prevention and Reclamation Introduction Rymer Cones Dump 13.3 Monitoring Rymer Cones and Implementing Fire Mitigation Introduction Rymer Cone No. 1 in a coal waste dump, Upper Silesian Coal Basin, Poland. The height of the cone is 23 m. The dump includes two other cones (not visible here) that were combined during redevelopment. Photo by Adam Tabor, 2007.
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Coal and Peat Fires: A Global Perspective Edited by Glenn B. Stracher, Anupma Prakash and Ellina V. Sokol Copyright © 2015 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/B978-0-444-59509-6.00013-2
13.1 Coal Waste Dump Fires Magdalena Misz-Kennan Mariusz Gardocki Adam Tabor
Photos by Adam Tabor, 2007 (top) and 2008.
Smoke exhaled from the SE part of the Rymer Cones waste dump and burnt plants at the dump. The horizontal fields of view are 40 m (top) and 3 m.
Introduction The problem of fires in coal waste dumps has existed throughout the history of organized coal mining. Dumps adjacent to coal mines were typically formed as cones from the beginning of the 1890s. In building the dumps, old techniques were used, which actually promoted the self-heating processes leading to endogenic fires. The processes of self-heating of coal waste has been investigated for many years (Beamish et al., 2001; Brooks et al., 1988; Clemens and Matheson, 1996; Hull et al., 1997; Itay et al., 1989; Kaji et al., 1985; Krishnaswamy et al., 1996a,b; Pone et al., 2007; Wang et al., 2003a,b). They are still not fully explained, although a number of hypotheses have been proposed. At present, it is believed that the oxidation of organic matter of coal waste is the precursor to the ignition of the waste (Krishnaswamy et al., 1996a; Lu et al., 2004; Singh et al., 2007). This hypothesis is based on the complex phenomenon of the sorption of oxygen in coal in contact with atmospheric air. In the 1980s, some rules were developed for the construction of coal waste dumps so as to inhibit fires. These rules were based on the widely accepted premise that self-heating and fire are possible only when three conditions are fulfilled at the same time (Urbański, 1983; Szafer et al., 1994; Tabor, 1999, 2002; Barosz, unpublished data; Pone et al., 2007). First, the deposited waste material must contain some combustible coaly material of the appropriate activity. The content of this coaly matter is variable, usually 5–20%, depending on the type of coaly matter (petrographic composition and coal rank), the technology of coal exploitation, and the coal enrichment processes. Second, there must be access to air into the interior of the dump, which must be conical and be composed of loose material. Third, there must be the possibility of heat accumulation within the dump. The exclusion of any one of these conditions will make the occurrence of endogenic fire unlikely if not impossible.
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Fire Prevention In the past, fires in coal waste dumps were a common phenomenon. Almost all dumps (typically cones) were subject to self-heating and combustion. Material deposited in these dumps was usually completely transformed. Dump combustion is a long-term process. Large dumps in which several million cubic meters of waste material may have been deposited will maintain high temperatures for a long time, even after completely burning out. During the extraction of burnt-out waste material for building roads, dumps that had not shown any evident thermal activity on the surface were discovered to have interior temperatures exceeding 400 °C. Such old and still thermally active dumps are sources of air and water pollutants resulting from the transformation of organic and mineral matter in the waste. The efficient and complete extinction of the fires is possible only by digging trenches or completely dismantling the dumps. New coal waste dumps should fulfill the fire prevention conditions. In these, the waste material is deposited in 0.5–1.0 m thick layers and compacted with vibrating rolls, slopes are properly formed, and the dumps are periodically monitored. In this way, the danger of fire is minimized. Elimination of air access into the interior of the dump is accomplished through good sealing. Any rise in temperature that occurs will be limited and will not lead to ignition. A temperature below 60 °C is considered safe. Higher temperatures are dangerous. The curve of temperature increase rises sharply to reach the temperature of ignition for bituminous coal at about 200 °C (Sawicki, 2004). A different situation can be observed when a new dump is located in contact with an old, burnt-out dump that is still thermally active. An old dump, partly or completely burnt out, is usually cold outside, hot inside, and in thermal equilibrium with its surroundings. The heating limit lies somewhere inside the old dump. The addition of fresh waste to the side of the dump causes disruption of the thermal equilibrium; the heating limit moves toward the outer parts of the old dump. In some unfavorable situations, it can reach the recently deposited material, and if the temperature exceeds 60 °C, it can rise further very rapidly to initiate endogenic fires in the new material.
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13.2 Technology for Fire Prevention and Reclamation
Photo by Adam Tabor, 2007.
Burnt plants on the southern slope of the Rymer Cones waste dump. The city of Rymer is in the background.
Introduction New fire prevention techniques utilize trenches filled with an inert incombustible material such as clay or fly ash. The purpose of such techniques is to prevent the transfer of fire from heated parts of the old dump into unaffected parts that are composed of new waste. This solution was proposed by the Central Mining Institute in Katowice (Poland) and was used for the first time when the older parts of the Rymer Cones in Rybnik (Upper Silesian Coal Basin, Poland) were surrounded by new waste material.
Rymer Cones Dump The Rymer Cones were formed in the early 1900s as three cones some 60–65 m in height located close to the Rymer Coal Mine (now closed) and, incidentally, very close to blocks of flats in the district of Rybnik town (Figures 13.2.1 and 13.2.2). At present, the dump occupies an area of 13 ha and its capacity is 2 million cubic meters. Over many years, these cones were almost completely burnt out. The thermal activity of varying intensity was a great environmental nuisance for people living in the nearby blocks of flats. At the end of the 1980s, an attempt was made to reclaim the dump. A new method to extinguish the fires was developed based on cutting off the access of air into the dump interior. The old waste dump was surrounded by new waste rocks using appropriate compaction and sealing material. It was planned that the cones were to be lowered and combined into one feature and its top prepared for sealing. Cone No. 1 was to remain as a view point. It was also planned that the border between the old and new material be surrounded by a moat (Figure 13.2.3) filled with inert incombustible material, mostly clays and fly ash from the power station. In 1995–1999, the reclamation works were carried out (Figures 13.2.3–13.2.7). The dump was rebuilt and cone No. 1 was retained (Figure 13.2.8). The highest point of the dump is 323 m above sea level. The cone showed no signs of heating. The formation of the top of the dump was a difficult undertaking due to the presence of numerous very large sinters in the former cone Nos 2 and 3 (Figures 13.2.3, 13.2.4 and 13.2.7). This was the end of the first stage to extinguish the fires in the Rymer Cones dump.
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Figure 13.2.1. Rymer Cones Nos 2 and 3 in 1996. Photo by Adam Tabor, 1996.
Figure 13.2.2. The beginning of the enclosure of Rymer Cone No. 2. Photo by Adam Tabor, 1996.
Figure 13.2.3. Formation of the moat filled with fly ash and clay surrounding Rymer Cone No. 3. The width of the road is about 5 m. Photo by Adam Tabor, 1996.
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Figure 13.2.4. Formation of the moat filled with fly ash surrounding Rymer Cone No. 3. The vertical field of view is about 35 m. Photo by Adam Tabor, 1996.
Figure 13.2.5. Formation of the moat filled with fly ash surrounding Rymer Cones Nos 2 and 3. Photo by Adam Tabor, 1996.
Figure 13.2.6. The beginning of the enclosure of Rymer Cone No. 1. The width of the road is about 5 m. Photo by Adam Tabor, 1996.
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Figure 13.2.7. Advanced works on the enclosure of Rymer Cone No. 3. Photo by Adam Tabor, 1996.
Figure 13.2.8. A general view from Wodzisławska Street of the eastern part of the Rymer Cones dump after reclamation. Photo by Adam Tabor, 2001.
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13.3 Monitoring Rymer Cones and Implementing Fire Mitigation
Photo by Adam Tabor, 2007.
SE part of the Rymer Cones waste dump, locally covered with fly ash (gray blocks). The vertical field of view is 10 m.
Introduction The first signs of reheating in the dump appeared in 2000. The former authorities at the mine implemented additional sealing of the dump. The hot parts of the dump were covered with concrete panels and fly ash making a concrete-like cover (Figures 13.3.1–13.3.4). These actions proved sufficient only for a short period. Cracks appeared in the new cover. The area of heating and combustion spread, initially in the higher parts of the western and eastern parts of the dump (Figures 13.3.5 and 13.3.6) and later at the top (Figures 13.3.7 and 13.3.8) and in the southern part. The signs of heating were most evident in the western part as this part is most exposed to the dominant winds from the west. The signs of heating were best seen during winter after snowfalls (Figures 13.3.9–13.3.17).
Figure 13.3.1. Western side of the Rymer Cones sealed with concrete panels and fly ash after the first signs of heating after reclamation of the dump. The height of the trees is 5 m. Photo by Adam Tabor, 2002.
Figure 13.3.2. Eastern side of the dump covered by concrete panels and sealed with fly ash, as it appears today. The height of the trees is 5 m. Photo by Adam Tabor, 2002.
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Figure 13.3.3. The western side of the dump covered with concrete panels and sealed with fly ash. The height of the poles is about 0.5 m, and they are used to support the concrete panels. Photo by Adam Tabor, 2002.
Figure 13.3.4. The western side of the dump covered with concrete panels and sealed with fly ash, showing the border between the enclosed and unenclosed parts of the dump. The height of the poles is 0.5 m, and they are used to support the concrete panels. Photo by Adam Tabor, 2002.
Figure 13.3.5. Visible heating on the SW slope, prior to redevelopment. The width of the road is 6 m. Photo by Adam Tabor, 2002.
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Figure 13.3.6. Burnt plants on the SW slope of the dump. The height of the pole is 1 m. Such poles are used to support concrete panels. Photo by Adam Tabor, 2004.
Figure 13.3.7. Gas emissions and cracks in fly ash covering the top of the dump. Photo by Adam Tabor, 2004.
Figure 13.3.8. View of the remains of Rymer Cone No. 1 and the top of the dump covered with a 1 m layer of fly ash. The height of the trees is 5 m. Photo by Adam Tabor, 2006.
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Figure 13.3.9. View of the western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2003.
Figure 13.3.10. The central part of the western side of the dump prior to redevelopment. The height of the trees is 5 m. Photo by Adam Tabor, 2003.
Figure 13.3.11. Hot spot without snow, on the western slope below the concrete panels and fly ash cover. The vertical field of view is 50 m. Photo by Adam Tabor, 2004.
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Figure 13.3.12. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The height of the trees is 5 m. Photo by Adam Tabor, 2006.
Figure 13.3.13. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The horizontal field of view is about 25 m. Photo by Adam Tabor, 2006.
Figure 13.3.14. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2006.
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Figure 13.3.15. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. Photo by Adam Tabor, 2006.
Figure 13.3.16. Western side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The remains of Rymer Cone No. 1 are visible. Photo by Adam Tabor, 2006.
Figure 13.3.17. Southern side of the dump prior to redevelopment. The dark areas on the slope are where snow has melted. The remains of Rymer Cone No. 1 are visible. Photo by Adam Tabor, 2006.
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Monitoring and Mitigation The whole dump was and is regularly monitored with regard to its thermal state. A few tens of measurement points were located in places where indications of heating were observed on the surface of the dump. Monthly measurements of CO, CO2, and O2 contents are carried out at the depth of 0.8–1.0 m and of temperature at the same depth and on the surface, following a methodology elaborated at the Central Mining Institute in Katowice. The experience gained from similar monthly monitoring carried out in the dumps of Marcel, Anna, Chwałowice, and Rydułtowy coal mines led to modifications in fire prevention methods in these and the Rymer Cones dumps— dumps where there is the possibility of heat transfer between old and new waste material. Further observations and monitoring in recent years has changed opinions. Based on recent experience, it was concluded that the problem of the fire prevention centered on the transfer of heat within the dump. This resulted in further changes in ways of fire prevention, new technologies, and the formation of new dumps abutting old dumps. The most basic element in the changes implemented in the Rymer Cones dumps was the excavation of the heated sites to cool them. These works were undertaken in 2004 and continue to the present day with positive results (Figures 13.3.18–13.3.38). The disadvantage of these excavations is the formation of dust, which leads to negative reactions from the people living in the nearby blocks of flats. The final results of these excavations was liquidation of the fire spots and the relatively rapid (several hours to several days) cooling of the adjacent areas in the dump (Figures 13.3.39–13.3.43). One of the undertakings was the removal of the concrete-like cover in the western part of the dump. The slope of the dump was made less steep. The result of the rebuilding of the western and southern parts of the dump was elimination of the active fire spots. Unfortunately, the entire western site of the dump is still heated as shown by the brown spots of venting hydrocarbons on the dump surface (Figures 13.3.44–13.3.47) as well as the steaming of the dump surface after rain. Such heating is relatively minor with temperatures on the surface higher by 10–20 °C than
Figure 13.3.18. The first excavations on the western slope of the dump, to eliminate the hot spots shown in Figures 13.3.9 and 13.3.10. Photo by Adam Tabor, 2004.
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Figure 13.3.19. The first excavated hot spot in the SW corner of the dump. The trenches shown are from where Figure 13.3.7 was taken. The height of the poles is about 1 m, and they are used to support concrete panels. Photo by Adam Tabor, 2004.
Figure 13.3.20. Western part of the dump and excavation of the heated area in the lower part of the dump. The length of the poles is about 1 m, and they are used to support concrete panels. Photo by Adam Tabor, 2006.
Figure 13.3.21. Western part of the dump and excavation of the heated area in the lower part of the dump near the pipes. The diameter of the pipes is 0.8 m. They are used to transport hot water from the Chwałowice Coal Mine to homes in Rymer, a district of Rybnik town. Heat energy from the water is then used to heat apartments in Rymer. Photo by Adam Tabor, 2006.
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Figure 13.3.22. Southern part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.23. A view of the SE part of the dump during reclamation. Photo by Adam Tabor, 2009.
Figure 13.3.24. SE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.25. SE part of the dump. The horizontal field of view is 25 m. Photo by Adam Tabor, 2009.
Figure 13.3.26. SE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.27. SE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.28. South-south east (SSE) part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.29. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.30. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.31. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.32. SSE part of the dump. The gray blocks on the right are the remains of a fly ash cover. The horizontal field of view is 20 m. Photo by Adam Tabor, 2009.
Figure 13.3.33. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.34. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.35. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.36. SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.37. SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.38. SSE part of the dump. The horizontal field of view is 10 m. Photo by Adam Tabor, 2009.
Figure 13.3.39. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.40. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.41. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.42. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
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Figure 13.3.43. The relocation of waste material used for cooling the SSE part of the dump. Photo by Adam Tabor, 2009.
Figure 13.3.44. Brown staining from hydrocarbons on the western side of the dump. Photo by Adam Tabor, 2006.
Figure 13.3.45. Brown staining from hydrocarbons on the southern side of the dump. Photo by Adam Tabor, 2006.
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Figure 13.3.46. Brown staining from hydrocarbons on the western side of the dump. Photo by Adam Tabor, 2006.
Figure 13.3.47. Brown staining from hydrocarbons on the southern side of the dump. Photo by Adam Tabor, 2006. those of the surrounding air. The western slope is mostly covered by plants throughout the year. The elevated temperatures, and the snowfall and rainfall, create a microclimate. During springtime and summertime, plant growth there is especially luxuriant with some plants reaching sizes much greater than normal (Figures 13.3.48–13.3.61). The result of these remedial actions was a reduction of the influence of the Rymer Cones dump on the environment. The whole dump is still heated. Its interior, mostly completely burnt out, still maintains high temperatures. Drillings carried out on the top of the dump in 2007 showed temperatures of about 300 °C at the outlet of the drill hole. As a result of these high interior temperatures, areas of smoking and gas exhalation have reappeared in various places on the dump (Figures 13.3.62–13.3.64). The thermally active sites are being excavated and cooled now. The eastern side of the dumps is interesting (Figures 13.3.65–13.3.76). On this leeward side, the upper parts of the dump have shown elevated temperatures at an almost constant level over several years. This part of the dump was not rebuilt. At the depth of about 1 m, the temperature is 65–75 °C and the CO content is 0.02 vol.%. Although dried out in several places, most of the slope is covered by low-level, evergreen plants. This slope is a nesting site for partridge and pheasant, and rabbits are common. In the past several months, the heating has moved into lower parts (Figures 13.3.62–13.3.64). As mentioned in the beginning, the rebuilding of the three cones proved very difficult due to the presence of largesize sinters similar to rock towers in the upper part of the cones. The crushing of the sinters required a lot of effort, which included even the use of explosives. Cones Nos 2 and 3 were leveled by about 20 m. The highest parts of the cones were moderately heated. After preliminary flattening, the top was leveled using waste rocks from the current coal mining and with humus soil before being sown with grass. After the reclamation of the dump, the first signs of heating appeared in 2000. The top was then covered with a layer of fly ash that in places exceeded 1 m in thickness. The present experiences show that this was a mistake. It is impossible to completely seal a dump, and the screens of clay and fly ash did not prevent the transfer of heat. As a result, fire spots appeared in the newly formed surface, cracks developed, and gas and smoke emissions of varying
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Figure 13.3.48. Plants migrating onto the western side of the dump. The height of the trees near the top of the cone in the background is 5 m. Photo by Adam Tabor, 2006.
Figure 13.3.49. Plants migrating onto the western side of the dump. The height of the plants is 0.7 m. Photo by Adam Tabor, 2006.
Figure 13.3.50. Plants migrating onto the western side of the dump. Photo by Adam Tabor, 2006.
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Figure 13.3.51. Plants migrating onto the western side of the dump. The height of the plants is 0.7 m. Photo by Adam Tabor, 2006.
Figure 13.3.52. Plants migrating onto the southern part of the western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.53. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
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Figure 13.3.54. Plants migrating onto the southern part of the western side of the dump. The horizontal field of view is 20 m. Photo by Adam Tabor, 2008.
Figure 13.3.55. The western side of the dump below the remains of Rymer Cone No. 1. Photo by Adam Tabor, 2008.
Figure 13.3.56. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
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Figure 13.3.57. The western side of the dump below the remains of Rymer Cone No. 1. The height of the plants is 1 m. Photo by Adam Tabor, 2008.
Figure 13.3.58. Abundant plants on the northern part of the western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.59. Abundant plants on the southwestern side of the dump. Photo by Adam Tabor, 2008.
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Figure 13.3.60. The western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.61. The western side of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.62. The southern part of the dump during reclamation work. Photo by Adam Tabor, 2009.
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Figure 13.3.63. The recent hot spot in the eastern part of the dump. The width of the road is 5 m. Photo by Adam Tabor, 2009.
Figure 13.3.64. The recent hot spot in the eastern part of the dump. The horizontal field of view is 4 m. Photo by Adam Tabor, 2009.
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Figure 13.3.65. Concrete panels and fly ash in the eastern part of the dump. Temperatures have remained constant (75–80 °C at 1 m depth) here for many years. The height of the poles is about 0.5 m, and they are used to support concrete panels. Photo by Adam Tabor, 2001.
Figure 13.3.66. Concrete panels and fly ash on the eastern side of the dump, below Rymer Cone No. 1. Photo by Adam Tabor, 2002.
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Figure 13.3.67. Concrete panels and fly ash on the eastern side of the dump, below Rymer Cone No. 1. The horizontal field of view is 10 m. Photo by Adam Tabor, 2002.
Figure 13.3.68. View of the southern part of the dump, from the eastern slope. Photo by Adam Tabor, 2002.
Figure 13.3.69. The east-south east (ESE) part of the dump. Photo by Adam Tabor, 2003.
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Figure 13.3.70. The ESE slope of the dump. The horizontal field of view is 2 m. Photo by Adam Tabor, 2006.
Figure 13.3.71. The ESE part of the dump. The same area as in Figure 13.3.70. Photo by Adam Tabor, 2006.
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Figure 13.3.72. The eastern slope of the dump. The horizontal field of view is 2 m. Photo by Adam Tabor, 2006.
Figure 13.3.73. Camomile growing on the eastern slope of the dump. Photo by Adam Tabor, 2008.
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Figure 13.3.74. Fly ash and the remains of concrete panels on the eastern slope of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.75. Fly ash and the remains of concrete panels on the eastern slope of the dump. Photo by Adam Tabor, 2008.
Figure 13.3.76. Fly ash and the remains of concrete panels on the eastern slope of the dump, below Rymer Cone No. 1. The height of the trees on the cone in the background is 5 m. Photo by Adam Tabor, 2008.
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intensity occurred (Figures 13.3.7 and 13.3.8). However, with the passage of time, the intensity of the heating in the upper part of the dump decreased and, now, steam and smoke emissions are to be seen only in places. The top of the dump is now covered by plants that migrated naturally into the dump (Figures 13.3.77 and 13.3.78).
Figure 13.3.77. The top of the dump covered with fly ash and a view of the remains of Rymer Cone No. 1. Photo by Adam Tabor, 2006.
Figure 13.3.78. A part of the top of the dump with the remains of Rymer Cone No. 1. The height of the trees on the cone is 5 m. Photo by Adam Tabor, 2008.
Conclusions The future of the Rymer Cones dumps depends on the future decisions of the owner of the dump—currently the coal company (Kompania Węglowa S.A.). The entire dump contains about 2 million cubic meters of partly burntout waste material with potential for use as aggregate. Dismantling of the whole reflects the necessity to maintain standards of environmental protection, mostly with regard to dust formation, which is impossible to avoid. However, the nearby blocks of flats, the necessity for complete reclamation of the dump after possible exploitation as aggregate, and high indirect costs make dismantling impossible at present. The dump interiors are heated, and there is a periodic necessity to extinguish active fire sites. A good solution would be to open the top of the dump to lower the temperature. This relatively easy means of cooling would inhibit the migration of hot spots within the dump and limit or even eliminate the thermal activity on the slope of the dump.
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Important Terms coal waste combustion Rymer Coal Mine Rymer Cones self-heating
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