POSTER PAPER PROCEEDINGS

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1 ITA - AITES WORLD TUNNEL CONGRESS April 2018 Dubai International Convention & Exhibition Centre, UAE POSTER PAPER PROCEEDINGS

2 Effect of Operational Parameters on the Performance of Raise Boring Machine During Pilot Drilling Aydin Shaterpour-Mamaghani 1, Hanifi Copur 2, Engin Dogan 3 and Tayfun Erdogan 4 1 Istanbul Technical University, Mining Engineering Department, Istanbul, Turkey, mamaghani@itu.edu.tr 2 Istanbul Technical University, Mining Engineering Department, Istanbul, Turkey, copurh@itu.edu.tr 3 Eczacibasi Esan, Balikesir, Turkey, engin.dogan@eczacibasi.com.tr 4 Sargin Construction and Machinery Industry Trade Inc., Ankara, Turkey, tayfun.erdogan@sargininsaat.com ABSTRACT Raise Boring Machines (RBMs) are the fast, safe and efficient drilling / boring machines are used for different purposes in mining and tunnelling especially for excavation of vertical and/or inclined shafts and drifts. The optimum raise boring system is designed or selected based on drilling / excavation performance, which depends mainly on mechanical (machine related), geological / geotechnical and operational parameters. This study aimed to investigate the effect of operational parameters (length of shaft and labor experience) on the performance of a RBM (machine utilization time, daily advance, net pushing force, instantaneous penetration rate, unit penetration, net cutting rate, consumed tricone bit torque as well as consumed tricone bit power, and field specific energy) during the pilot drilling of two shafts in the Balya lead-zinc underground mine. The lengths of first and second shafts were and m, respectively. The inclination of these shafts was 69o and 68o, respectively. The pilot drill diameter of the two shafts were both m. The field investigations indicated that increasing the length of shaft decreased the overall performance of raise boring operation. In addition, labor experience is one the important factors for higher daily advance rates and lower time-sink during the drilling operation. Key Words: Raise boring machines, Operational parameters, Pilot drilling, Performance evaluation 1. INTRODUCTION Mechanical excavation takes an important role in mining and tunnelling industries as a strong alternative to conventional drill and blast method. Design, selecting, performance prediction and optimization are important subjects in mechanical excavation machines for feasibility and planning purposes. Shaft construction is now safe and fast operation using the most modern methods. Raise Boring is a full-face excavation method that means whole cross section of the hole is drilled to the desired diameter with no use of explosive. A raise boring operation generally consists of two stages as pilot drilling and reaming. A RBM uses a small diameter drill rod, around mm to drill a pilot hole down to the required depth. Then, the pilot drill bit is removed and replaced with a large diameter reaming head. The reaming head is usually then pulled back up to the upper level, creating a round shaped shaft. In the pilot drilling, the cuttings are removed from the hole with the aid of flushing. However, in the reaming stage, excavated material fall by gravity to the bottom of the hole and from where the muck is continually are removed. 1

3 Access to both top and bottom locations of the hole is a prerequisite for conventional raise boring method. The flexibility in different angles/gradients/inclinations and diameters is a great advantage compared to drill and blast excavation method. In the raise boring method, continuous operation provides a faster advance rate than other methods. This method is suitable in both hard and soft rocks being usually in massive nature. A RBM creates a shaft with smooth walls that usually do not require lining. The hole is more stable than a drilled and blasted hole and has better airflow, making it ideal for ventilation purpose. Raise boring is convenient method in competent rock; however, several problems are faced in geological formations where geological discontinuities are dominant. In such cases, shaft-boring time extends for supporting shaft walls. Visser (2009) stated that rock formations having several geological discontinuities were risk factors prolonging the termination of shaft boring process. In such cases, a detailed geotechnical evaluation or raise bore rock quality assessment based on the McCracken and Stacey (1989) method was recommended in the case of deep and / or large diameter shafts (Peck and Lee, 2008). Moreover, assembly and disassembly time may be long in some cases. Machine specifications and excavated rock / rock mass properties are two crucial factors in performance estimation of mechanical miners. Quite limited studies have been published in the literature related to performance estimation for RBMs. Morris (1969) developed a semi-empirical method for estimation of boring rate and cutter life. In his method, button penetration index with the other factors were used to estimate the machine performance. Seiler (1972) developed a boreability index for sphero-conical tungsten carbide inserts used in shaft drilling machines. Calder (1972) suggested an empirical model to estimate boring rate from drilling studies. His rotary drilling model relates boring rate to uniaxial compressive strength of the rock, thrust force and hole diameter. Dollinger (1977) stated that the machine advance rate and cutter life had to be balanced to obtain optimum performance in RBMs. Bilgin (1989), Dollinger et al. (1998) and Bilgin et al. (2014) stated that, penetration index obtained from indentation tests could be used to estimate the RBM performance. Shaterpour-Mamaghani and his colleagues investigated RBM performance in different shaft projects in Turkey; and suggested some empirical models to estimate performance and operational parameters of RBMs (Shaterpour-Mamaghani and Bilgin 2016; Shaterpour-Mamaghani et al. 2016a; Shaterpour-Mamaghani et al. 2016b; Shaterpour-Mamaghani et al. 2017). Shaterpour-Mamaghani and Copur (2017) stated that, the parameters affecting selection, design and predicting performance of a raise boring machine can be classified into three general categories: mechanical (machine related) parameters, geological / geotechnical parameters and operational parameters. Operational parameters included site preparation, shaft dimension and inclination, bailing system, utility facility (power, water, and air), applied torque, pulling / pushing force, penetration rate, labor availability and quality. Increasing shaft diameter causes additional torque effort on drill string and reamer stem. In addition, with the increase in diameter, there is a greater potential for instability of the shaft walls and the advancing face of the shaft. 2 In this study, the Balya lead-zinc underground mine in Turkey was visited to record operational and performance parameters of a RBM for a pilot hole drilling operation. The recorded performance parameters included machine utilization time, daily advance, net pushing force, instantaneous penetration rate, unit penetration, net cutting rate, consumed tricone bit torque as well as consumed tricone bit power, and field specific energy. Then the effects of operational parameters (length of

4 shaft and labor experience) on the mentioned performance parameters during the pilot drilling of two shafts are discussed to provide useful guides for the future RBM applications. 2. DESCRIPTION OF THE PROJECT 2.1. General overview of the Balya lead-zinc underground mine and shaft projects Balya lead-zinc underground mine located in Balikesir province of Turkey (Figure 1). Eczacibasi Esan industrial group has been operating the Balya mine since The sublevel stoping method is used for extraction. An incline ramp with a slope of 14.5% is used as the mine main gallery to minimize the transportation distance from the ore production area to the main gallery. The ore deposit generally had formed in contact area of limestone-dacite and crack of limestone. The underground mine main gallery is 6500 m long, 5 m height and 5 m width in horseshoe shape. Paleozoic and Triassic rocks are characterized by recrystallized limestone, metasandstone, meta-clayey sandstone and chloritic clayey siltstone (Ciftci et al. 2013). Figure 1. Location of the Balya lead-zinc underground mine 3

5 The management of the Balya lead-zinc mine was decided to use A RBM for excavation of ventilation shafts in The main reasons for this decision were the cost-effective, safe and efficient operation, which would be provided by a RBM. In the same year, the first shaft with m length was excavated with RBM in 38 days (16 days for pilot drilling and 22 days for reaming). The second shaft with m length was excavated in 37 days (16 days for pilot drilling and 21 days for reaming) in the same year. After these successful operations, the management decided to continue use of RBM for excavation of another ventilation shafts. A general profile view of the excavated shafts and mine is given in Figure 2. As seen, the first and second shafts were excavated between the 1217 and 1010 m levels. Then, the third and fourth shafts were excavated between the 1010 and 810 m levels. However, in the excavation of the fifth shaft (RBM 5.1) in 2015, the operation was stopped due to a cavity between the 201 and 234 m levels. Later on, it took more than 6 months to fix this problem with an injection operation. Then, the mine management decided to excavate the shaft with 1.5 m shift from the initial point. Finally, the inclined fifth shaft was excavated between the 805 and 505 m levels (RBM 5.2) in The pilot diameter of all drilled shafts was m. In addition, the final diameter of all excavated shafts was 2.44 m. Figure 2. General view of Balya lead-zinc underground mine and ventilation shafts Specifications of RBM Sandvik Rhino 1088 DC raise boring machine was used to excavate the all ventilation shafts. The specifications of the RBM are summarized in Table 1. Figure 3 shows the photographs of the RBM, pilot bit and reamerhead. Pilot hole drilling was based on rotational methods using a tricone roller bit of 311 mm diameter. The reamerhead is equipped with 14 button cutters. Seven cutters consist of five rows of tungsten carbide bits and another seven cutters consist of four rows of tungsten carbide bits. 4

6 Table 1. Main specifications of Rhino 1088 DC raise boring machine. Parameters Excavation Length Excavation Diameter Thrust Break out Torque Reaming Torque Rotational Speed of Pilot Drilling Rotational Speed of Reaming Power Demand Mass (without crawler) Value 610 m m 4000 kn 300 knm 160 knm 0-60 rpm 0-21 rpm 400 kva 16,500 kg Figure 3. Photographs of Raise boring machine (left side), tricone bit (middle) and reamerhead (right side). 3. FIELD STUDIES The first shaft (Shaft 1) drilling was started on 20 October However, after the m, the pilot hole drilling operation was stopped on 20 November Figure 4 shows the daily and cumulative advance rate during this operation. The mean daily advance rate was 8.09 m/day. 16 Daily Advance Cumulative Advance 250 Daily Advance (m) Cumulative Advance (m) Date Figure 4. Daily and cumulative advance rate in pilot drilling of Shaft 1. 5

7 The machine commenced drilling pilot hole of Shaft 2, on 4 February 2017 and completed on 23 March. The total length of this hole was m. Figure 5 shows the daily and cumulative advance rate during this operation. The mean daily advance rate was 8.86 m/day. Daily Advance Cumulative Advance Daily Advance (m) Cumulative Advance (m) Date Figure 5. Daily and cumulative advance rate in pilot drilling of Shaft 2. The inclination of first shaft was 69o, and the inclination of second shaft was 68o. The working pattern was 12 h/shift, 1 shift/day and 6 day/week in both shafts. One operator, one chief and two workers were used for these operations. The mean measured values of RBM operational parameters (drilling time, rotational speed, consumed tricone bit torque and net pushing force) and calculated performance parameters (instantaneous penetration rate, unit penetration, consumed tricone bit power, net cutting rate and field specific energy) in pilot drilling of these two shafts are summarized in Table 2. It is should be noted that, the length of used drill string was m (the length of the stabilizer was 1.44 m). Table 2. Measured / calculated operational and performance parameters in pilot drilling. Parameters Shaft 1 Shaft 2 Drilling time (min.) Rotational speed (rev/min) Consumed tricone bit torque (knm) 6 8 Consumed tricone bit power (kw) Field specific energy (kwh/m 3 ) Instantaneous penetration rate (m/h) Unit penetration (mm/rev) Net cutting rate (m 3 /h) Net pushing force (kn)

8 4. EFFECT OF OPERATIONAL PARAMETERS ON PERFORMANCE OF THE RBM Length of shaft, shaft dimension and inclination as well as labor availability and quality (labor experience) are important factors in the operational parameters. In this section, the details of the effect of length of shaft and labor experience on the overall performance of the drilled pilot holes are discussed. It should be noted that there was only 1.5 m spacing between the two pilot holes. Labor experience is one of the vital factors in the obtaining optimum daily advance in the drilling operation. The first shaft (pilot hole) drilling was completed in 26 working days with average daily advance of 8.09 m/day. By consider this average daily advance; the second shaft (pilot hole) drilling should be completed in 42 days ( / 8.09 ~ 42). However, due to obtained experience from the first shaft drilling, the second shaft drilling was completed in 38 days with average daily advance of 8.86 m/day. As seen, the increasing experience of labor could decrease the shaft drilling time and this lead the cost reduction during the shaft construction. Machine utilization time (MUT) is another important factor in determining the drilling efficiency and economy. MUT is defined as the ratio of the net drilling time of the machine to the total working time. Advance rate is average machines advance rate per day, including all delays. Figure 6 shows the time distribution of different activities in the Shafts 1 and 2 during pilot hole drilling. As seen, in the first shaft drilling, the problem related to the water (water cut and tank cleaning) caused 3% delay during pilot drilling. However, the blasting operation in the other levels of mine caused 1% delay during pilot drilling of second shaft. The drill string attachment (tear down) time in both shafts was same as 10 minutes for each drill string (rod). Despite 2% difference between drilling operation of these shafts, it could not be concluded that the utilization time of the first pilot hole is more efficient than the second pilot hole. Because, the second pilot hole was 125 m longer than the first pilot hole. In addition, the other delays in the second shaft included bentonite injection that it has not been made in the first shaft. Figure 6. Time distribution of different activities during the shafts drilling (left side: Shaft 1 and right side: Shaft 2). 7

9 The field investigation showed the difference between the performance parameters of these two shafts. In the first shaft, after 200 m drilling, the operator saw an unusual change in the parameters that shown in the data acquisition system. In the drilling of the 207 m, the instantaneous penetration rate was 2.61 m/h; unit penetration was 3.9 mm/rev; net pushing force was 120 kn; consumed tricone bit torque was 9 knm, and field specific energy was kwh/m3. However, in the drilling of the 210 m, the mentioned parameters were changed to m/h, 60.8 mm/rev, 5 kn, 6 knm, and 2.27 kwh/m3, respectively. After this stage, the operator stopped the drilling operation. Then, the geological investigation showed the cavity between the 201 and 234 m levels. Later on, it took more than 6 months to fix this problem with injection. Finally, the mine management decided to drill the shaft with 1.5 m shift from the initial point. The experience obtained from the first shaft drilling, helped the operator to be familiar with the difficulties of the inclined shaft construction. To overcome these difficulties, the exploration borehole with 330 m length was drilled to detect the different geological zones. Due to this investigation, the m length of shaft was detected as the fault zone. The RBM performance parameters showed different manner between the zones. The upper level of the fault zone was named as limestone-1 zone. The RBM performance parameters between m drilling of limestone-1 were recorded as 2.28 m/h of the instantaneous penetration rate, 3.17 mm/rev of the unit penetration, 120 kn of the net pushing force, 9 knm of the consumed tricone bit torque, and kwh/ m3 of the field specific energy. However, these parameters in the fault zone were changed to 2.89 m/h, 16 mm/rev, 55 kn, 11 knm, and kwh/m3, respectively. The lower level of the fault zone was named as limestone-2. The RBM operational and performance parameters between m drilling of limestone-2 showed different values. In this depth interval, the instantaneous penetration rate was recorded as 1.22 m/h; the net penetration was recorded as 1.69 mm/rev; the net pushing force was recorded as 120 kn; the consumed tricone bit torque was recorded as 13 knm, and the field specific energy was recorded as kwh/ m3. As discussed, the instantaneous penetration rate in the fault zone was the highest value among the zones. The net pushing force was decreased in the fault zone (55 kn); however, this parameter increased again in the lower level of the fault zone (120 kn). On the one hand, the rotational speed, instantaneous penetration rate, and net pushing force parameters in the second shaft decreased to 12.2 rev/min, 1.44 m/h, and 122 kn, respectively. On the other hand, the consumed tricone bit torque, unit penetration, consumed tricone bit power, and field specific energy increased to 8 knm, 3.53 mm/rev, kw, and kwh/m3, respectively. It is obvious that, the operator decreased the two controllable parameters of RBM (rotational speed and net pushing force) to overcome the rod jamming and rod failure; however, in the 114th and 119th rods two jamming incidents occurred. The other reason for this difference is related to the drilled rocks. As stated, in the second shaft, the machine drilled different zones; especially in the transition zones, the machine performance parameters changed in wide range. Furthermore, it is known that there is a reverse relationship between instantaneous penetration rate as well as net cutting rate with field specific energy. Therefore, increase in the field specific energy is reasonable. 8

10 5. CONCLUSION The present study investigated the effect of length of shaft and labor experience (as operational parameters) on the performance parameters of RBM during the pilot drilling of two shafts in the Balya lead-zinc underground mine. The first shaft length was m and the second shaft length was m. Some of the results of the field studies are summarized as follow: In the first shaft, the instantaneous penetration rate was 1.54 m/h. However, this parameter in the second shaft was 1.44 m/h. The net pushing force values were recorded as 161 and 122 kn in the first and second shaft, respectively. In the first shaft, the consumed tricone bit torque was 6 knm. However, this parameter in the second shaft was 8 knm. This investigation showed that the labor experience is the key element in the daily advance. The second shaft was 125 m longer than the first shaft. Nevertheless, the daily advance of the second shaft (8.86 m/day) was higher than the first shaft (8.09 m/day). In addition, experienced labor could decrease the time-sink during the drill string attachments (tear down). Another conclusion drawn from this study is the decreasing the rotational speed, instantaneous penetration rate, and net pushing force parameters with increasing of the shaft length. The RBM gives an opportunity to the operator to change some controllable parameters such as rotational speed and net pushing force during drilling operation. As a conclusion remark, it is inevitable fact the other operational parameters such as different shaft inclinations and diameters, as well as other RBM types, should be included in the future investigation to improve the trustability of this research findings. ACKNOWLEDGEMENTS This paper summarizes some of the results of Ph.D. research work carried out by Aydin Shaterpour-Mamaghani. The authors are grateful to the support of Eczacibasi Esan lead-zinc underground mine and Sargin Construction and Machinery Industry Trade Inc.; this work would be impossible without their support. REFERENCES Bilgin N (1989) Applied Rock Cutting Mechanics for Civil and Mining Engineers. 1st ed. Birsen, Istanbul (In Turkish). Bilgin N, Copur H, Balci C (2014) Mechanical Excavation in Mining and Civil Industries. 1st ed. CRC Press, New York. Calder PN (1972) Rock Mechanics aspects of large hole boring machine design. In: 8th Canadian rock mechanics Symposium, pp Ciftci Y, Revan M.K, Sen P, and Zimitoglu O. (2013) The basic geological aspects of Eskisehir, Balikesir, Tepeoba, Izmir, and Usak ore deposits. International Workshop on Base and Precious Metals, Field Trip Guide Book, May 20-27, MTA, Ankara, Turkey. pp Dollinger G.L (1977) Choosing cutters for the best boreability. Compressed Air Magazine, Sept., pp

11 Dollinger GL, Handewith HJ and Breeds CD (1998) Use of the Punch Test for Estimating TBM Performance. Tunnelling and Underground Space Technology, 13 (4): McCracken, A., Stacey, T.R. (1989). Geotechnical risk assessment of large diameter raise-bored shafts. Shaft Engineering, Institution of Mining and Metallurgy, pp Morris RI (1969) Rock drillability related to a roller cone bit. In: Proceedings of society of petroleum Engineers of AIME. Paper No. SPE 2389, pp Peck, W.A., Lee, M.F. (2008). Application of the Q-System to Australian Underground Mines. In: Proceedings of the International Workshop on Rock Mass Classification in Underground Mines, U.S Department of Health and Human Services CDC/ NIOSH Office of Mine Safety and Health Services, pp Seiler WK (1972). Hard rock boring with tungsten carbide insert big cutters. In: 1st North American Rapid Excavation and Tunneling Conference, Chicago, Proceedings Volume 2, pp Shaterpour-Mamaghani A, Bilgin N (2016) Some contributions on the estimation of performance and operational parameters of raise borers A case study in Kure Copper Mine, Turkey. Tunnelling and Underground Space Technology, 54: Shaterpour-Mamaghani A, Bilgin N, Balci C, Avunduk E, Polat C (2016a) Predicting Performance of Raise Boring Machines by Using Empirical Models. Rock Mechanics and Rock Engineering, 49 (8): Shaterpour Mamaghani A, Erdogan T, Engin D, Bilgin N (2016b) Evaluation of the Performance of a Raise Boring Machine in Pb-Zn Underground mine, Balya, Turkey. World Tunnel Congress, San Francisco, USA. Shaterpour-Mamaghani A, Copur H (2017) Factors Affecting the Selection and Performance of Raise Boring Machines (RBMs) and Case Studies from Turkey. In: 26th International Symposium on Mine Planning & Equipment Selection Conference, Luleå, Sweden, pp (ISBN: ). Shaterpour-Mamaghani A, Copur H, Bilgin N, Kocbay A, Erdogan T (2017) Raise Boring Machine performance in the Yusufeli Dam and HEPP Project. World Tunnelling Congress (WTC2017), Bergen, Norway. Visser, D. (2009). Shaft Sinking Methods Based on The Townlands Ore Replacement Project-Rise Boring. In: The Southern African Institute of Mining and Metallurgy Shaft Sinking and Mining Contractors Conference, 13p. 10

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