AERIAL ROPEWAYS.pptx

Mining

1. AERIAL ROPEWAYS Sunday, February 06, 2011 1 AERIAL ROPEWAYS

2. Some Interesting Facts HAULAGE by rope and pulley has been known since the earliest days, and although no graphic record is available, the evidence has been furnished by wooden pulleys found during excavations in Egypt. These pulleys date from about 2600 B.C. The first practical aerial ropeway of which there is any definite evidence was devised by Adam Wybe , a Dutch engineer. During the construction of a fort at Danzig he used an aerial ropeway for the conveyance of earth from a hill outside the fortifications to the fort under construction. Sunday, February 06, 2011 2 AERIAL ROPEWAYS

3. An endless rope, attached to which was a number of small buckets, ran between the two terminal points and was supported by intermediate standards. The buckets were filled at the hill and travelled on one side to the fort, where they were emptied and returned on the other side back to the hill. The rope ran round pulleys at both terminals and was driven by hand Sunday, February 06, 2011 3 AERIAL ROPEWAYS

4. Definition: An aerial ropeway is defined as a transport system in which transit material is carried in purpose made cars suspended from over head ropes. Advantages: It can negotiate steep gradients upto 1 in 2 as there is independence of adhesion between rail and wheel. It can have shortest routes. In other transport systems, such luxury may not be possible because of terrain difficulties. Sunday, February 06, 2011 4 AERIAL ROPEWAYS

5. It has an ability to cross the land used by the owner for other purpose. It can work in fog, rain etc. without any difficulty. The power cost is estimated to be the least than any other alternative system for handling equivalent quantities on the same route. It can negotiate adverse terrain like mountainous regions, dense forests etc. Automation is easy. Sunday, February 06, 2011 5 AERIAL ROPEWAYS

6. Disadvantages: Difficult for supervision in case the infrastructural facilities are located in remote areas. Degradation of mineral takes place if the requirement is that of the coarse and impurities may get attached to the mineral fragments. Generation of dust can also be a menace. Sunday, February 06, 2011 6 AERIAL ROPEWAYS

7. Classification and Parts of aerial ropeways In general the ropeways can be classified as: Monocable aerial ropeways Bicable ropeways The parts of ropeway: Wire rope (s) Trestles Loading and unloading stations Angle stations Buckets Sunday, February 06, 2011 7 AERIAL ROPEWAYS

8. The Monocable aerial ropeway The monocable aerial ropeway employs a single endless wire rope for both supporting and transporting loaded and unloaded buckets. Each bucket is suspended by a hanger from a box head equipped with two clips at 430 mm centres from driving contact with the rope. Two 200 mm diameter wheels mounted on the box head are used for traversing on the rails. Sunday, February 06, 2011 8 AERIAL ROPEWAYS

9. Bucket and Hanger on a Monocable Aerial Ropeway Sunday, February 06, 2011 9 AERIAL ROPEWAYS

10. Salient Features of Monocable Aerial Ropeway It is used for relatively small capacities Lower capital cost as compared to Bicable aerial ropeway. The ropeway is not used on a gradient in excess of 1 in 5 because the box head clips cannot provide adequate driving force. Note: Capital cost of ropeway depends upon weight of individual buckets as the rope strength is controlled by the same. It has been observed that the reduction in the loading time can increase the capacity substantially without requiring increase in the rope speed and bucket capacity. Sunday, February 06, 2011 10 AERIAL ROPEWAYS

11. Wire Rope (s) Ropes for monocable ropeways The rope supports both the buckets (track) and carries them in the required direction (haulage). The selection of the rope is governed by: Bending stress: It is induced in the rope by the mass of the bucket. The mass depends upon the ropeway capacity and its speed. Tension: It is developed because of ropeway capacity and the route profile. Sunday, February 06, 2011 11 AERIAL ROPEWAYS

12. The approximate tension will vary from 30 kN to 100 kN. Round strand ropes of size 6 × 7 are used. The factor of safety is normally 5. In general the diameter of the ropes is either 16 mm or 32 mm. The diameter of the sheaves is 100 to 120 times the diameter of the rope to avoid the bending stress. Sunday, February 06, 2011 12 AERIAL ROPEWAYS

13. The Bicable aerial ropeway The bicable aerial ropeway employs two separate track ropes with which buckets are suspended. There is an endless haulage rope. Each of the track rope is anchored at one end and tensioned at other end. The haulage rope is of flexible construction. A 6 × 7 Lang’s lay rope with fibre core can be used as haulage rope. Spliced rope can be used as haulage rope. Sunday, February 06, 2011 13 AERIAL ROPEWAYS

14. Ropes for bicable ropeways It has two ropes one is track and other one is a haulage rope. The track rope is a locked coil rope. The tension in the rope is 60 to 70 × the individual wheel load. Wheel load is the mass of loaded bucket divided by the number of wheels. Usually the number is 2 or 4. Sunday, February 06, 2011 14 AERIAL ROPEWAYS

15. The track rope is a triangular strand or round strand rope. The determination of haulage rope diameter depends upon the capacity of the ropeway. Sunday, February 06, 2011 15 AERIAL ROPEWAYS

16. Sunday, February 06, 2011 16 AERIAL ROPEWAYS

17. Trestles They are usually fabricated from steel sections. The trestles are 6 to 10 m high. The maximum height of a trestle depends maximum sag. It is advantageous to have a trestle as low as practicable. Sunday, February 06, 2011 17 AERIAL ROPEWAYS

18. Monocable Trestles The top arms support 350 – 700 mm diameter rope carrying sheaves. The sheaves are so placed at a distance of 450 – 900 mm centre to centre. The figure shows the trestles used in Monocable aerial ropeways Sunday, February 06, 2011 18 AERIAL ROPEWAYS

19. Sunday, February 06, 2011 19 AERIAL ROPEWAYS

20. Trestles for Bicable Aerial Ropeways They do not need sheaves fixed to the trestles fitted to the upper works. In the upper part the telephone and signal wires are attached. Flying stays are provided for the rollers over which the rope can slide. The trestles are used on both sides of a bridge which is used when the aerial ropeway crosses a road. Sunday, February 06, 2011 20 AERIAL ROPEWAYS

21. Sunday, February 06, 2011 21 AERIAL ROPEWAYS

22. Angle Stations When the direction of the aerial ropeway is to be changed, the same has to be done at the terminal station. Sometimes we have to install angle stations for the purpose. Pulleys are mounted on vertical shafts. The vertical and horizontal deflection is achieved by suitably arranging the rope to pass over the pulleys. Sunday, February 06, 2011 22 AERIAL ROPEWAYS

23. Angle Station Sunday, February 06, 2011 23 AERIAL ROPEWAYS

24. Loading Station It consists of structure made up of steel. It supports the return sheave for the rope. The buckets get disengaged from the rope and run on the rail. The power for the movement is either by manual means (now obsolete) or by a chain haulage. When the bucket arrives at the selected feeder, it is placed on a weighment bridge. Sunday, February 06, 2011 24 AERIAL ROPEWAYS

25. The feeder loads a pre-set quantity in the bucket. After loading, the bucket is pulled by the haulage. The bucket later on catches on the rail. For high capacity, a rotary loader is used. The loader ensures continuous loading without any interruption. For small capacity, a hopper and chute arrangement is used. Sunday, February 06, 2011 25 AERIAL ROPEWAYS

26. Loading Station Sunday, February 06, 2011 26 AERIAL ROPEWAYS

27. Rotary Loading System Sunday, February 06, 2011 27 AERIAL ROPEWAYS

28. Carriers/Buckets Three types of buckets are used Simple rotating buckets. Bottom discharge buckets. Totally enclosed buckets. Simple rotating buckets: The bucket is locked in position by a simple catch gear. The catch is released at the unloading station. The bucket overturns its content and returns to the loading station in inverted position. They are unsuitable for the transportation of sticky materials. Used on Monocable ropeway. Sunday, February 06, 2011 28 AERIAL ROPEWAYS

29. Bottom discharge buckets They are widely used on bicable aerial ropeways. Suitable for the transportation of wet and sticky material. At discharge end the bottom door is opened and the material is discharged cleanly. The lids close automatically due to their weight. Sunday, February 06, 2011 29 AERIAL ROPEWAYS

30. Bottom Discharge Bucket Sunday, February 06, 2011 30 AERIAL ROPEWAYS

31. Totally enclosed buckets These buckets are used when When minerals reactive towards water are to be transported e.g. pyritic ores. Very fine materials are to be transported. The buckets are bottom discharge type Sunday, February 06, 2011 31 AERIAL ROPEWAYS

32. The Drive Terminal The drive terminal incorporates a discharge arrangements before the terminal. The drive arrangement consists of an arrangement similar to that of the endless haulage. The wheel has a brake path. Thruster brakes are provided to apply the brakes in case the motor rotates in opposite direction. Sunday, February 06, 2011 32 AERIAL ROPEWAYS

33. Drive Arrangement Sunday, February 06, 2011 33 AERIAL ROPEWAYS

34. Drive Arrangement Sunday, February 06, 2011 34 AERIAL ROPEWAYS

35. Discharge Stations There are basically three methods for consideration: Depositing between trestles: The trestles are 30-40 m high and are spaced at 90-100 m. Means are provided for the tipping the buckets. The material is deposited at its normal angle of repose along a convenient width. The disadvantage is that the trestles progressively get buried. Sunday, February 06, 2011 35 AERIAL ROPEWAYS

36. Tipping by means of a self advancing station: The buckets leave the ropeway. They travel on a rail arranged at right angles. The buckets move along a rail by a chain haulage system. The tipping can be arranged at any point along the rail. The entire station is mounted on a caterpillar. After the station has advanced a distance of 100 m; a new set of trestles is installed. The height of the muckpile that is obtained is 6-9 m. Sunday, February 06, 2011 36 AERIAL ROPEWAYS

37. Self Advancing Station Sunday, February 06, 2011 37 AERIAL ROPEWAYS

38. Extending frame ropeway: The system has the least cost amongst the all the three methods. The bucket coming from the ropeway discharges its content while passing round a sheave. The normal climbing angle is 20 . The last Tresle is lost as loading trestle. Sunday, February 06, 2011 38 AERIAL ROPEWAYS

39. ARERIAL ROPEWAYS CALCULATIONS Monocable aerial ropeway Static friction : 1.5 kW to 4 kW Effort to raise to load: CD/400 kW Line friction: CL/20000 kW Gearing losses: 80% Sunday, February 06, 2011 39 AERIAL ROPEWAYS

40. ARERIAL ROPEWAYS CALCULATIONS ( Contd. ) Bicable aerial ropeway Static friction : 1.5 kW to 4 kW Effort to raise to load: CD/300 kW Line friction: CL/13000 kW Gearing losses: 80% Where ‘C’ is ropeway capacity, teph ‘L’ is the total line length, m ‘D’ is the level difference between the loading and unloading station, m Sunday, February 06, 2011 40 AERIAL ROPEWAYS

41. For transporting uphill Power = 1.2 (a + b + c) For transporting downhill Power = 0.8 (a - b + c) Rope sag = w × S 2 /(0.7 × T) Load sag = W × S/(0.4 × T ) Distributed sag = R × S 2 /(0.7 × T) Where S is the horizontal distance between the trestles; T is the rope tension (N); w is rope weight (kg/m); W is the weight of loaded bucket (kg); R is the Bucket weight rate = loaded mass of the bucket/ bucket spacing Sunday, February 06, 2011 AERIAL ROPEWAYS 41

42. An aerial ropeway transports the mineral over a length of 6700 m. The delivery point is 58 m above the loading point. The ropeway capacity is 450 te /h and the speed is 245 m/min. The bucket capacity can be assumed to be 1650 kg. Solution = The bucket/h = 450/1.65 = 272.73 Allowable time per bucket = 3600/272.73 = 13.2 s Rope speed = 245 m/min = 4.08 m/s Load spacing = 4.08 × 13.2 = 53.9 m Sunday, February 06, 2011 42 AERIAL ROPEWAYS

43. Number of full buckets = 6700 / 53.9 = 125 (say) Power = 1.2 (4 + 87 + 232) = 1.2 (293) = 352 kW Sunday, February 06, 2011 43 AERIAL ROPEWAYS