Journal of Mining Science, Vol. 46, No. 4, 2010

EFFICIENCY OF SINGLE PASS LONGWALL (SPL) METHOD IN CAYIRHAN COLLIERY, ANKARA/TURKEY

F. Şimşir and M. K. Özfırat Longwall mining is the underground coal mining method mostly used in Turkey. Most of the collieries in the country produce coal from thick coal seams. The three methods mainly used worldwide in thick coal seams are longwall top coal caving (LTCC), multi-slice longwall (MSL), and, single pass longwall (SPL) methods. As shearer-loaders and roof supports get larger in size, the SPL method has started to be used widely both in Turkey and all over the world. In Turkey, ParkTeknik Co., a private mining company, has an important place among the many collieries in Turkey as it is the first mine which started applying the SPL method in a thick coal seam having a total thickness of 4.2 m including a soft dirt band which is between 50 – 80 cm thick. In this paper, the performance of the longwall using the SPL method at the ParkTeknik’s Cayirhan colliery is examined for a period of six months. Face and overall productivities are analyzed by taking into account labor and breakdown figures. The results showed that the mine operates at the level, or even higher, of international standards. Single pass longwall, thick coal seam, colliery, efficiency INTRODUCTION

Most of the coal seams in Turkey mined out in underground are thick coal seams (e.g. Tuncbilek, Soma, Cayirhan lignite fields) and about half of the lignite reserves of the country constitutes of thick coal seams [1]. Coal seams which cannot be mined out at a single pass are to be defined as thick coal seams. In the 80’s and 90’s, this thickness was said to be about 4 m. As technology developed, it is now possible to extract thick coal seams of 5.5 – 6 m thickness at a single pass. The studies carried out in 2000 and 2002 [2 – 4] showed that it is possible to produce seams of 4.5 m thickness by single pass longwalling since there exist equipments higher than 4.5 m. The Lazy mine in Slovakia has a cutting thickness of 5.5 m and the mine operates by SPL with roof supports of 6 m height (Fig. 1a). Similarly, in South Africa, the height of roof support in Matla mine reaches up to 6 m (Fig. 1b) [5]. The first example of SPL in Turkey appears at ParkTeknik colliery’s sector C, in Cayirhan/Ankara (Fig. 1c). In this sector, the thicknesses of upper coal, lower coal and dirt band are 1.7 m, 1.9 m and 0.5 – 0.8 m, respectively. The overburden thickness amounts to between 150 to 250 m. To the west of the region, the thickness of the dirt band rises to 1.3 – 2 m, on the other hand, to the east of the region, it decreases to 0.5 – 0.8 m. Since in sector C the thickness of the dirt band is low enough, here, the upper and lower coal seams are mined, including the dirt band, together by SPL (Fig. 2) [6, 7]. In this study, the total working times, the coal cutting times, and the breakdown times in three shifts are examined for six months. Moreover, the face and overall efficiencies resulting from these examinations are computed and given in tables and graphs. DEU Engineering Faculty, Mining Engineering Department, Mine Mechanization and Technology Division, E-mail: [email protected], [email protected], Buca-İzmir, Turkey. Original article submitted May 6, 2006. 1062-7391/10/4604-0404 ©2010 Springer Science + Business Media, Inc. 404

Fig. 1. Equipments of thick coal seams operating by SPL: a, b — abroad; c — in Turkey

Fig. 2. Cross-section of longwall operating at ParkTeknik’s sector C 405

LOCATION OF STUDY AREA AND PANEL DATA

The mine lies about 125 km northwest to Ankara. It was run by the state-owned Turkish Coal Enterprises (TKI) until 2000, where it was privatized and handed over to ParkTeknik Co. (refer to Fig. 3). Today, coal production continues at 5 sectors, namely sectors A, B, C, F and G, the first one of which was taken into mining by TKI. The mining method utilized is retreating fully mechanized longwall with caving, whereby SPL is used at sector C, and separate faces for top and bottom coals at the other sectors. Coal mined out is fired at a nearby 620 MW power station. At sector C, an Eickhoff SL-500 double-drum shearer-loader is used for getting coal, that has 2×500 kW motors for the drums, 2×54 kW motors for advancing, and, a 35 kW motor for its hydraulic pump. Total installed power is about 1148 kW and the operating voltage is 3300 V. While cutting, it advances at a maximum speed of 10.07 m/min. The machine is 14.27 m long and has 76 cutting bits on each globoid-type drum, which rotates at 23 rpm. The diameter and width of the drums are 2300 mm and 900 mm, respectively, and the machine has a maximum cutting height of 5.09 m. The coal produced in the face is transported by a 2×400 kW double-drive double-chain AFC, manufactured by the German DBT, to the stage loader in the main gate, and from there onto the 1200 mm wide belt conveyor in the main gate. Both the AFC and the stage loader have a capacity of 2000 t/h, and chain sizes of 34×126 mm. The AFC operates at a speed of 1.11 m/s. As support units, SaarTech’s 25/50L type double-leg shields are used, opened height of which is 5 m. Each unit weighs 25.6 t and has a setting force of 3400 kN. At face ends, three STBS 27/50L type four-leg shield units are used, which weighs 38.3 t each. The panel length is set as 1700 m, and the face length as 220 m. To avoid spontaneous combustion, to increase recovery of coal reserve, and to use gate roads twice (each main gate is used as the tailgate of the next panel), a rib-side concrete packing of 3 m width and at coal seam height is used as part of gate road support.

Fig. 3. Location of the study area 406

WORKING TIMES AND EFFICIENCIES

Shift working times, face and overall efficiencies of sector C are examined for 6 months. Number of workers which are used in the determination of efficiencies are given in Table 1 by their works. TABLE 1. Distribution of Workers at Sector C Longwall by Their Works Shift 1

Work

Shearer operator + cable controller Shield operator Face end supports + concrete packing Return end supports + concrete packing Shield advancing team Monorail AFC driver Midstation for concrete packing Maintenance of shearer-loader Maintenance of support units Electrician for shearer-loader Electrician at stable-hole TOTAL

3 3 4 4 4 4 1 3 3 3 2 1 35

Shift 2

3 2 4 4 4 3 1 4 3 3 2 2 35

Shift 3

3 3 5 4 5 3 1 3 3 3 2 1 36

TABLE 2. Face and Overall Efficiencies Shift

Coal production, t

Number of work days

Number of face Number of Face efficiency, Overall efficiency, workers underground workers t/man-shift t/man-shift

April (1) Shift 1 Shift 2 Shift 3

18165.68 41385.16 28426.16

Shift 1 Shift 2 Shift 3

83229.57 80242.12 76983.31

26

19 18 21

24

19 18 21

35 35 36

12.26 29.47 17.35

6.65 15.16 10.12

35 35 36

60.84 61.91 50.92

33.03 31.84 29.70

35 35 36

62.69 69.97 62.12

34.03 35.98 36.24

35 35 36

71.75 71.16 64.27

38.95 36.60 37.49

35 35 36

62.90 54.45 56.37

34.15 28.00 32.88

35 35 36

52.07 52.10 40.70

28.27 26.80 23.74

May (2)

June (3) Shift 1 Shift 2 Shift 3

92902.2 98235.5 101756.3

26

19 18 21 July (4)

Shift 1 Shift 2 Shift 3

102244.7 96070.4 101230.9

Shift 1 Shift 2 Shift 3

93218.3 76450.2 92326.5

Shift 1 Shift 2 Shift 3

77172.0 73149.2 66664.8

25

19 18 21

26

19 18 21

26

19 18 21

August (5)

September (6)

407

Fig. 4. Face efficiencies

Fig. 5. Overall efficiencies

As it can be seen from Table 1, number of workers employed in moving face and face-end roof supports forward is greater than that used in other operations. This is because advancing roof supports forward consists of complex and hard operations. From the view of production efficiency, it is important to allocate a sufficient number of workers to face operations at every shift (Table 2). At fully-mechanized longwall mining, coal-getting, transportation of coal and advancing roof supports are carried out mechanically [8]. Therefore, allocating a sufficient number of workers to each operation could increase face and overall efficiencies (Figs. 4 and 5). As can be seen from Fig. 6, the highest percentage of time is allocated to coal cutting and to auxiliary operations of production in all three shifts. Mechanical and electrical breakdown durations do not exceed 10 % of total working time, which shows that production process continues without major problems (Table 3). Since SPL application at sector C of the mine is the first application in Turkey, efficiencies are important, and, this study shows that SPL is quite an efficient method for Cayirhan colliery’s sector C.

Fig. 6. Distribution of operation times by work type 408

TABLE 3. Works and Breakdowns in Shifts and Their Durations over a Period of 6 Months Shift, min

Breakdown reasons

1

2

3

11120 490 405 2380 945 340 170 365 — 1870 — 1895 845 30 16375 37230

8635 550 170 945 845 60 35 340 — 405 75 1260 530 185 23115 37150

— 150 — — 1975 50 275 — — 3660 6110

— 315 535 665 1475 225 420 — — 3525 7160

895 170 210 245 155 1675 49642 94657

510 70 85 105 370 1140 49875 95325

Auxiliary works Face-end support preparations Return end support preparations Replacing spare parts Filling stowe boarding Preparation of stowe boarding Blockages of chain conveyor Blockages of belt conveyor Overload of AFC Overload of belt conveyor Advancing support units Moving stowing bunker Advancing stage loader Preparation for advancing stage loader Controlling picks Other auxiliary operations Total

8790 125 230 1660 665 175 150 610 130 510 30 1045 675 — 20510 35305

Mechanical breakdowns Shearer-loader oil level control Winch maintenance Ranging arm maintenance Drum maintenance AFC maintenance Gear unit maintenance Chain repairs and maintenance Stage loader welding operations AFC welding operations Other mechanical breakdowns Total

15 150 — 755 405 145 375 65 65 3935 5910 Electrical breakdowns

Shearer-loader related AFC related Stage loader related Belt conveyor related Other electrical breakdowns Total Coal cutting duration Total working time

725 380 — 325 1070 2500 49760 93475

409

CONCLUSION

Throughout the study, it is seen that face and overall efficiencies increased for the first three months, then the efficiency figures started to deteriorate. But, still, both the face and overall efficiencies are quite high when compared to similar collieries. These figures can be improved even more by decreasing the mechanical and electrical breakdown durations and the duration allocated to auxiliary operations. Considering the technological development all over the world, it will soon be possible to extract coal seams over 6 m thickness by the SPL method, both in Turkey and all over the world. REFERENCES

1. H. Kose, S. Senkal, and A. Akozel, “Is the caving method application in longwall mining which are most commonly used in Turkish thick coal seams economical?” in: Proceedings of the 11th Turkish Scientific and Technical Mining Congress [in Turkish], Ankara (1989). 2. B. K. Hebblewhite, “Review of Chinese thick seam underground coal mining practice,” The Australian Coal Review, Issue 10 (2000). 3. (http://www.australiancoal.csiro.au/articles_mining.html) 4. B. K. Hebblewhite, A. Simonis, and Y. J. Cai, “Technology and feasibility of potential underground thick seam mining methods,” School of Mining Engineering, UNSW/CMTE ACARP Project C8009, Final Report UMRC 2/02, ISBN 0 7334 1945 3 (2002). 5. B. K. Hebblewhite, “Status and prospects of underground thick coal seam mining methods,” in: Proceedings of the 19th International Mining Congress and Fair of Turkey, IMCET 2005, Izmir, Turkey (2005). 6. Y. Aydin and Y. Kaygusuz, “Evaluation of single-slice and twin-face operations of Cayirhan lignite seams,” in: Proceedings of the 17th International Mining Congress and Exhibition of Turkey, IMCET 2001, ISBN 975395-417-4, Ankara, Turkey (2001). 7. S. Por, “Investigation of “C” sector of ParkTeknik Co.,” Undergraduate Thesis [in Turkish], D.E.U. Engineering Faculty Mining Engineering Department, Izmir (2002). 8. S. S. Peng and H. S. Chiang, Longwall Mining, John Wiley& Sons Inc. (1984).

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