Chapter No. 1 - Transport of ore Underground transport arrangements are divided into two categor: 1) MainHaulage/Underground to surface 2) Gathering haulage/ Underground to surface 3) Surface to surface Underground to surface/The main haulage arrangement is that which operates between winding shafvincline and the main underground loading points. At the main loading point, the loads are collected from one, two or more districts. ‘Underground to surface/The gathering haulage arrangement is that which operates between the working faces and the main loading points. In a large mine, where the working faces are far from the main loading point, an intermediate transport arrangement operates and it is known as secondary haulage. The main methods of transport are as follows: A) Rope Haulages B) Locomotive haulage 1) Direct ropehaukge 1) Diesel locomotive a) Sing: drum direct rope haulage 2) Blectric locomotive . a) Overhead wire locomotive b) Doubk drum direct rope haulage b) Trolky wire locomotive 3) Electric battery locomntive 2) Main & tail rope haulage 4) Compressed air locomotive Endless rope haulag 3) Endless rope haulage ©) Conveyor systemof haulage a) Under rope endkess rope haulage 1) Belt conveyor 2) Chain conveyor D) Arial Ropeway b) Over mpeendless rope haulage 3) Gravity rope haulage Scanned with CamScannerA) Rope haulage 1) Direct Rope Haulage a)Single Drums Direct Rope Haulage: run on inclines steeper than 1 in 12 & This is simplest system of rope the speed of the haulage is 8 - 12 haulage. It consists of one track, one km/h. rope & one drum which are connected to a motor through gears. One end of the rope is connected with the train of tubs on the track & another end of the rope is connected to the drum. When the drum rotates situated at the top of the incline, the loaded tubs moves upwards. But for the downward journey of the empty tubs it does not require any power because a tub moves downward due to their own weight. The system can Advantages of Single Drum Direct Rope Haulage . Simplein operation. . Only one brake is required. Extension is easy. . Branched roads can also be served, if gradient is suitable. Yawnp }. Can be used in narrow roads. Disadvantages of Single Drum Direct Rope Haulage 1. High power demands for upper journey of loaded tubs. 2. Efficient breaking system required for downward journey. 3. High speed haulage demands more maintenance of track. 4. Cannot be used for less incline roadways. 5. Aderailment is associated with heavy damages. Scanned with CamScanner6. Due to high speed more dust, more wear & tear. b)Double Drum Direct Rope Haulage: another drum. It can be used if Itconsists of two drums, two ropes & inclination is more than 1 in 12. The two tracks but only one driving speed of the system is 8 to 12 km/h. motor. One end of each rope is connected with two drums & another end of rope is connected with theset of tubs. In such a way that when one set of tub is at incline top, the other set is at incline bottom. The two drums are connected with each other. When drum rotates, the rope coils on one drum & uncoils from Advantages of Double Drum Direct Rope Haulage 1. Higher output. 2. Less power demand. 3. Branched roads can also be served, if gradient is suitable. Disadvantages of Double Drum Direct Rope Haulage 1. Wider roads required. 2. Efficient breaking system required for downward journey. 3. High speed haulage demands more maintenance of track. 4. Cannot be used for less incline roadways. 5. Aderailment is associated with heavy damages. 6. Dueto high speed more dust, more wear & tear. 2) Main & Tail Rope Haulage:- In this type of haulage engine is provided with two separate drums, one for main rope which hauls the loaded tubs, one for tail rope which hauls the tubs downward the gradient, when one drum is in gear the other drum revolves freely but controlled. The name implies the haulage has a main rope and a tail rope. Scanned with CamScannerThe engine being provided with two separate drums one for each rope. The main rope coils on a drum, is attached to the front end of the loaded drums to haul them out bye. The tail rope from a second drum, passing over a return pulley sheave in bye, is attached to the rare end of the full tubs .n the tail rope hauls the empty tubs in bye. brakes are fitted to each drum and the drums are so arranged that each may be driven independently through clutches when one drum is in gear other revolve freely but itis controlled , when necessary it is kept tight with the brake . The length of the rope needed is more than three times the haulage road ~ the main rope is equal to the length of haulage and the tail rope is twice the length of the main rope. This system can be operated 12-18 km or even up to 20 km per hour. This system needs only a single track except in the landings and pass byes, and can be employed in narrow road ways. The engineman has complete control of the train right throughout its journey. Motive power is used only when the train is making itsjourney. Special shackles are used to attach the tubs or set to. the rope. 3) Endless rope haulage: In this system an endless rope made up of several length spliced together , passes from the driving pulley at the out bye end of haulage plane to a return pulley the driving pulley also known as the surge pulley it is moved by electric power from the motor through number of gears wheel's turning through sustainable shaft . The rope may pass around pulley only 2 and a half- 3 and a half times and then Scanned with CamScannerreturn. The friction between the rope and the pulley surface prevent the rope slipping. But too few turns of the rope on the pulley might allow slip. Again too many turns might cause the rope to fasten itself on the pulley. Expect on very haulages itis necessary to have rope tensioning arrangements. The endless haulage speeds range about 2-5 km per hour this system is ideal for roadways 1 in 16 gradients. Two sets of rails are required for endless haulage system, one for the empties going in bye, one for the full tubs being drawn out bye. a)Under Rope Endless Rope Haulage Under rope haulage has the advantage that there is a more direct pull on the draw bars, the tubs may be fully loaded, curves are more easily worked, automatic detachment of clips can be readily arranged and the moving rope, being near the floor, is less liable to personal injury. The method is suitable for roadway of varying gradient b) Over Rope Endless Rope Haulage:-It requires fewer rollers the rope is not affected by wet floor and there is less friction and wear of rope and slippers. The rope is not liable to corrosion. The rope is at a better working height for person engage in attaching and detaching tub. The method is suitable for roadway of varying gradient. Scanned with CamScannerThe endless haulage is simple to work, effective on varying gradients and can negotiate curves usually at the cost of manpower: it can be readily extended and tubs taken right to their final destination. It is capable of hauling over long distances, the tonnages normally collected from a number a subsidiary haulages or conveyor loading points. further advantages of this method are : coping with larger outputs than other types of rope haulages , simple in layoutand operation : low speed , lowered risk of accident of accident and other damages : reduce liability to airborne and roadway dust, less wear and tear track and rolling stock ; applicable to level , undulating and inclined roadways, while negotiating bends of moderate nature , constant load imposed on motor: less maintenance on the hauler due to elimination of high speed revolving parts and simplified layout. Driving Pulley or Surge Wheel Pulleys or wheels which are used for driving purposes on haulages must haveits throatso shaped as to give the necessary grip to prevent jar and shock ypes of Driving Pulley & Surge Wheel 1.Clifton Pulley: This pulley has tapered throat lining of renewable cast iron or soft steel segment having a tape of about 1 in 8. These segments are bolting to the rim to protect the main pulley from wear. The ropeis coiled several times (3 % - 4 %) around the pulley & it enters the pulley at larger diameter & leave the pulley at smaller diameter. This pulley is commonly used in mines in endless haulages. Scanned with CamScanner2. _V-Grooved Pulley: A v grooved pulley or clip pulley is suitable for light haulages. A good grip fob the rope is obtained, thereby preventing slip. Both sides of the throat are made in segments and bolted to the rim of the wheel. These pulleys have a rim of the wheel. These pulleys have a tendency to flatten the rope by wedging and greater the load the greater the wedging. 3. Fowler’s pulley: This is a form of clip pulley, the throat of which is made in several segments. This is an improvement on the v- groove type and is designed to overcome the friction resisting the entrance to and resisting from the taper throat of the pulley. When the rope passes on to the open groove of the pulley, the segments are passed down and rotated about their pivots, thus increasing the grip on the rope. The segments are adjustable to allow for wear and ropes of different diameter. Scanned with CamScannerRope clips The endless ropes moves at a slow speed over pulleys or rollers situated between the rails in the haulage way. Special clips are used for detaching tubs or cars to the moving rope. The design of such clips depends on whether the rope travels under the tubs, or over the tubs. The clips used for under rope haulage are- 1.Screw clip or Hadfield clip 2. Small man clip 1, Screw clip:-The clip is tightened on the ropeby a handle and a screw. Itis coupled to the tub drawbar by a long steel rod hinged to the clip. Scanned with CamScanner2) Small man clip: - A small man clip consist of a pair of steel cheeks or side plates, loosely held together by an adjustable central bolt it has a spring surrounding it to keep the plates apart. The top of the clip is expanded by means of special designed operated lever wedge. When the lever I depressed, the wedge enters the narrower part of the space between the plates, so forcing them apart at the top, and at the same time causing the bottom jaws to grip the rope. When the lever is raised, the wedges move the wider part of the space between the plates so releasing the top from the jaws. The clip is provided with a coupling hook attached with the tubs. Small man clip can be automatically detached from the tubs by fixing a trip bar at a convenient height so that the lever of the clip strikes it to make the grip ineffective. Clips used for over-rope haulage 1) Lashing chain 2) Goose neck clip 3) Camelip 1) Lashing chai: Scanned with CamScanner3. Gradient operated tension: This is also a mobile tension where the gradient allows in vicinity of the haulage engine a bogie sheave can be placed on an inclined roadway which may be connected with loaded tubs with sufficient weights to move backwards and forwards in accordance with necessity. Where reverse gradient are met with it might be necessary to install a take up tension at each end of the haulage plane. Since slack rope would have to be taken up on both sides of engines. The correct places for the tension device is at the point where slack are mostlikely to occur. Scanned with CamScannerGravity haulage The gravity haulage or self-acting incline is adopted to transfer loaded Kid from one elevation to a lower one in mines. The system doesn't require any motor or any source that of power where the roadways are sufficiently steep and gradient uniform and in favor of the load. The gravity haulage of the full load is the power supplied to overcome the gravity load of the empty set and rope, together with friction of full tubs running downwards and empty tuba moving up. Itis usual to work the self-acting incline with a single rope -one end attach to the full set, The rope passes 1% times the around the cast iron pulley known as jig pulley or brake wheel 1.3 m to 2m diameter, with a Frodo - Line lever operated strap brake , firmly secured in an anchor prop in the top of the incline near the advancing coal face. A safety prop is placed in front of the pulley .The other end of the top passes to a bogie, around a pulley there on and so back uphill to a holding of prop where it is firmly secured by a clamp. Itis also secured to safety prop where it is firmly secured bay clamp. It is also secured to a safety prop and the surplus prop rope is coiled on a drum nearby in readiness for when the face advances. By operating the brake wheel, chitrolling the lever the loaded tubs may be automatically move downward pulling the balancing bogie up the track. Itis possible to maintain an ordinary double track in the gateway, the bogie may be dispensed with empty tubs pulled up by each descending full tubs. The system having a double track for the full tubs. The system having the double track for the Scanned with CamScannerfull length of the incline for a set or train of full tubs, in descending, pulling an equal number of the tubs is known as train incline. Such inclines call for a well - laid track, good rope and roller, and a strong brake wheel. Three rails may also be used in above meeting or pass byes having four rails or double track and an ordinary single track below. The least gradient for a gravity haulage depend on- The length of the plane. The size, capacity, weight, and conditions of tubs and their numbers. The state of the roadway in regard both of layout and maintenance Some authorities suggest 1in20 is being the least gradient, but each case requires its own diagnosis. Safety precautions: The safety measures to be taken for the gravity haulage include- |. Large roadways, adequate lightning, well- laid tracks with proper maintenance, strong and reliable couplings chains etc. ll, Backstays behind ascending tubs, and back catches or spring catches to prevent empty tubs running downwards down the incline. lll. Safety prop in the front if the jig wheel to hold the rope in the event of pulley anchorage failure. IV. Drop Warwick near the top of incline and a bottom to rests tub in case of forward runway. Runaway switch to derail tubs and arrest them for a same reason. V. Asecond brake on the brake wheel should be provided which acts directly ‘on the rope itself to prevent runaway of full tubs if they should be lowered into the incline without an empty set having been attached to the top at the bottom the brake wheel securely fenced and a guard erected to prevent men running into the handle of brake. Safety devices Apart from the falls of ground, haulage and transport operations have been responsible for a greater number of accidents involving deaths and Scanned with CamScannerinjuries than any other single cause. The major proportion of haulage and transport accidents results from runaways. The various safety devices used on haulage roadways are as follows: 1. Stop blocks 2. Buffers 3. Back catch 4. Pointer plate 5. Drop warrick 6. Age craft device 7. Back stays or drags 1.Stop_ blocks: A stop block is a common arrangement placed near the top of inclines. It consists of a stout beam or blocks lying across the rails, pivoted at one end and held against a pivoted side block at the other .the side —block may be straight cor bent, When it is desired to open the blocks, side block is opened and then the stop —block is turned as shown in the figure 2. BUFFERS: When any roadway or face is in direct line with a haulage track and persons may be exposed from runaway tubs, strong buffers is provided and maintained on haulage road to prevent danger. Buffers may be horizontal or vertical. 8. Runaway switches 9. Jazz rail 10.Retarders and stoppers 11 Approach warning devices 12.Signalling arrangements Scanned with CamScanner3. Back catches: These are made in different forms. It may consist of a pivoted piece of steel rail placed between the two rails as shown in figure. Tubs can move over it only in one direction. In case of backward runway it will catch the tub axel thus arresting the tubs. A shout wooden block pivoted at one end and passed over the rail by strong spring allows the tubs in one direction only and prevents runaway in case of spring catch. 4. Pointer plates: This is fitted on the main haulage track to deflect a backward runaway into the prepared side of the roadway. The derailed tubs may be automatically re-railed when drawn forward. 5. Dropwarrick: It consists of a girder hinged at one end to a specially set roof girder and held up at the other by an eye bolt and pin. The warrick is released when required in emergency by a haulage worker pulling the wire to withdraw the pin. It may also be operated automatically when the uncontrolled movement of tubs give a long swing to an operating handle. An obvious disadvantage is that excessive impact into the warrick may displace the roof support thus causing a roof fall if the warrick post is hinged to a roof bar. It is essential therefore to anchor the warrick to a girder not forming part of the roof support but firmly set into the sides of the roadway thought must also be given to the sitting of the warrick between refuge holes, avoiding possibility of accidents to persons sheltering therein. The automatic closing type of warrick are also used which are balanced by weights. The drop girder is slightly heavier than the weightof the rod attachment Scanned with CamScannerin this case. The moving tub itself strikes the weight rod to cause dropping of the girder at some distance. Such warricks can be operated by means of 1) a weight rod suspended from the roof 2) a side warrick in which a side arm is balanced to return to the closed position either by gravity or by asset of weights after alast tram has passed the type has the swinging movement controlled by balance weights and pulleys. Warricks can be arranged to have an automatic tripping device in corporate that comes in an operation when the normal speed is exceeded. This works on the principles that the trams travelling at normal speed move a pendulum without disconnecting the slip link which is holding the drop girder by means of a chain and cable. If the certain speed is exceeded the pendulum is struck a harder blow and the sufficient to release the slip link and thus causing the girder to drop to the closed position. 6. Age craft device: This is designed to arrest forward runways automatically. These work on the principle that the first axle of the tubs depresses the forked end to axle height. If the tub is passing on the normal speed, the forked and the drops before the back axle reaches it. Ifthe tub is moving fast, the back axel is held by fork and the tub is stopped. 7. Backstays: Any train of tubs ascending an incline shall have a drag or backstay attached to the rear tub so as to prevent the train fromrunning back. These may be attached to the tub axel or to the tub drawbar according to their types. Scanned with CamScanner8. Run Away Switch: This switch is normally kept open by a spring. When a lever handle is operated by an operator, the switch gets closed. And tubs can pass over it otherwise the tub derails when they pass over the runaway switch. It is used with direct rope haulage & main & tail rope haulage. 9. Runaway Switch & Stop Block: This safety device is situated at the incline mouth of direct or main & tail ropehaulage. In this safety device the stop block & the runaway switch are so interconnected that at any time one of them is working. The distance between stop block & run away switch should be more than the train length (train length + 4.5 meter). The stop block & the primary switch are connected by a lever. When the lever is operated to clear the track from the stop block the runaway switch is open. But as soon as the tubs crosses stop block the lever is again operated to close the runaway switch & at the same time it is on the stop block. Scanned with CamScanner10.Jazz rails: The principle of this device is that tubs travelling at normal speed passes over section of the jazz track negotiating the bend readily. Ifthe tubs travel at excessive speed, as in the case of the runaway. They will fail to get round the bend and a derailment occurs. Rails should be bent in the correct radius. 11. Retarders: Slowing down and stopping tubs are integral parts of haulage operation. A hand operated retarder consists of two planks, lined on the top with belting and mounted on cams. An end cover plank fastened to the inside faces of planks serves to hold the plank in position. They are operated by a single lever. When the cams are fully raised, the tub wheels are lifted clear to the rails and a braking action is provided on the axle. Scanned with CamScannerThe tub retarders represents waste of energy and should be avoided in planning. However, the speed movement of tubs required for quick turn over and higher rising may make its application essential at pit top, pit bottom haul brow heads etc. There are many types of elaborate designs and manually control. Smooth breaking may be affected by air or hydraulic breaking. Fully automatic retarders, which are released by pneumatic cylinder, are widely used. The device consist of two pairs of hinged bars faced with renewable skid plates and breaking action effected by movement of two opposing pistons of ina cylinder containing air. The bars are raised above the rail level and grip the wheels. When no braking is desired, the value releasing to the atmosphereis opened after cutting of compressed air supply. A spring draws back the breaking bars to normal Position, An automatic hydraulic tub retarder is suitable for locomotive haulage or ordinary rope haulage. The hydraulic pressure is supplied from 1-2 KW eclectically driven Scanned with CamScannerpump. The oncoming tramp is retarded by the tread of the leading wheels running fixed skids and an inclined hinged platform which acts as a wedge. 12. APPORACH WARNING DEVICE: Itis sometime necessary to warn man working or travelling in a haulage roadway. A simple way of operating a warning device in a rope haulage roads is an arm protruding into the path of oncoming trams which, when deflected closes an electric circuit connected to a signal lamp or a bell. The device is operated by a lever depressed by tram axle. 13. Spring Catch: It consists of a wooden block at one end & pressed sideways over the rail at the other end by a spring as shown in figure. The tub moving in proper direction pushes aside the wooden block & passes over it, but due to spring the wooden block at once returns to its original position to arrest a backward run away tub. It is used in endless rope haulage. 14, Manholes: Height should be more than 1.8 meter, depth should be more than 1.2 meter & width should be more than 0.7 to 1 meter. When person are allowed to work or pass through an incline, when the haulage is in motion, the manholes are made along the roadways so that person travelling can take shelter in the manholes. The interval between two manholes should not be more 10 meters, but if the gradient is less than 1:6 the interval may be up to 20 meter. If the roadways are less than 1.8 meter in height the manhole should be made up of full height of the roadway it is used in direct, main & tail & endless rope haulages. Scanned with CamScannerLOCOMOTIVES Main Parts of Locomotives 1) Chasis:Chesis is rigid frame work of steel section. 2) Driving wheels, axles, springs & brake blocks etc. mounted below the Chasis. 3) A_power Unit: it may be a diesel engine, an electric motor, a battery or compressed air. 4) Operator's Cabin: Having control panel with brakes, operating system, horn etc. 5) Lights at both ends. 6) Ascrew brake for emergency. 7) For large size locomotives an air compression for power brakes. Scanned with CamScannerLocomotive Haulage: In case of rope haulage the power to move the load is available from external fixed motor to the haulage. While in case of locomotive haulage the driving unit i.e. locomotive is coupled to a train due to which more safety can be attained. The locomotives are very flexible in nature & they can be used for men transport also. ‘Types of Locomotive Haulages are:- 1) Diesel locomotive 2) Electric locomotive 1) Over head wire locomotive 2) Trolley wire locomotive 3) Electric battery locomotive 4) Compressed air locomotive 1)Diesel Locomotive: Diesel locomotive are commonly used in number of mines. Their weight varies from 3 tonne to 15 tonne & power from 50kw to 75kw. The power unit is a diesel engine. The locomotives used in underground coalmines havea power unit in a flame proof enclosure asa safe guard against ignition of fire damp. In coal mines the diesel locomotives are notallowed where the percentage of inflammable gases is more than 1.25% in the general body of air. Hence these are generally used in intake roadways. The exhaust of the diesel engine includes oxygen, nitrogen, carbon dioxide & small quantities of oxides of sulphur & nitrogen & other aldehydes which smell badly &causes irritation of the nose, throat & eyes. To remove these oxides & aldehydes the locomotives are fitted with exhaust conditioner Advantages of Diesel Locomotives 1. Cheaper 2. Completely self-controlled Disadvantages of Diesel Locomotives 1. Danger of fire in handling the diesel. Le Scanned with CamScanner2. production of poisonous gasses 3. Adds heats to the atmosphere. 4. More maintenance required. 5. More employees required. Exhaust Conditioner & Flame Trap: The exhaust gases from the engine strikes on the surface of the water in the chamber A. This traps hot particles & washes out the sulphur oxides & aldehydes. The gases then rise through a flame proof slag wool which is kept moist by water & thereafter pass through second chamber. Similar chamber B, where gases are further cooled & filtered before passing through the flame trap. A flame arrester consists of a removable stainless steel plates 1/2mm apart. Finally gases are mixed with about 30 to 40 times their volume of fresh air before entering in the atmosphere. In chamber A, a water level indicator is installed in such a way that if water level falls below certain level, the brakes are applied automatically. The exhaust conditioner should be replaced by aclean set after every 24 hours. Eetnont Conarioner (1) Gryneerteen (2) Condivionng ehemtient, (2) Conte ‘valoe with Moat, (4) Water (6) Titer Box (0) Continone cham 1 (7) Fle trap 0) Fan, (8) Milking chamber (10) Exhaust ovtet stmamchere (A) iow water me (0) Bates (5) Stercer 2)Electric Locomotives: The electric locomotive is equipped with an electric motor which draws the current from the overhead wires through a pantograph or through a long pole which is kept pressed against the overhead conductor by spring tension. The DC supply to overhead wires is 250 volts. These locomotives Scanned with CamScannermay be used in degree | gassy mines. The overhead wires are suspended through insulators over the track at a height more than 2 meter. Advantages of Electric Locomotives 1) More reliable 2) Light weight 3) Less maintenance 4) Good control 5) Small size 6) No exhaust gases Disadvantages of Electric Locomotives 1. High initial investment 2. Danger of shock & fire 3. Derailment is major problem 3)Electric Battery Locomotives: The power unit of an electric battery locomotive is a DC electric motor which receives current froma storage battery carried in the locomotive itself. Such locomotives are for light & medium duties. The batteries are of lead acid type & each battery consists of a number of 2 volt cells & their no varies from 40 to 70. The capacity of the battery to work is 8 hours & its charging time is also 8 hour. Advantages of Battery Locomotives 1) Less maintenance. 2) No poisonous gases. 3) No overheads wire's problem. 4) Quite in operation. Disadvantages of Battery Locomotives . Hydrogen gas is liberated. . Flame proofing is not possible. |. Overheating of cell may cause sparking or fire. . Large cross section. . Expensive batteries & less life. Po Scanned with CamScanner wPwne6. Special charging stations involve more cost. 3) Compressed Air Locomotive: There are no compressed air locomotives in Indian coal mines, The source of power used in air locomotive is compressed air cylinder, installed over the locomotive. This cylinder supplies the required quantity of compressed air to the locomotive. These locomotives are very safe, reliable & very useful in hot & deep mines. Even though their working cost is very low, they are not used in Indian coal mines due to their high cost of installation. These locomotives are used for light duty work only. Advantages of Compressed Air Locomotives 1) Very safe. 2) Very reliable. 3) Less maintenance required. 4) Cooling effect of air. Disadvantages of Compressed Air Locomotives 2) Danger of pipe leakage. 3) Efficiency is less. Super Elevation/Cant: On a curve, centrifugal action creates a tendency for the train to leave the track & proceed along a line tangential tothe curve. This makes the wheel flanges very hard against the inner edge of the outer rail, causing more wear on wheels & rails. To counter act this; the outer rail should be raised above the inner one. This level difference between the inner rail & outer rail is known as super elevation. S.E. = AV2/g.r meter. Where, A= gauge width in meter. V= velocity in meter/sec. = acceleration due to gravity (9.8 meter/sec) Scanned with CamScannerr=radius of curvein meter. Ideal Gradient: If the Tractive force required to haul the loaded trail down the gradient is same as it is required to haul the empty train of the gradient with the same velocity, this gradient is known as ideal gradient Let, WL= Weight of loaded train. WE = Weight of empty train 1inn=Ideal gradient }.= coefficient of friction Case I: When loaded t moving downward GL=WLg.1/n FL=WLg. ( TF=FL-GL TF=WL. g. (-WLg 1/n- Case Il: When empty train is moving upward GE=WE.g.1/n FE=WEg TF =FEHGL TF =WEg (+ WE.g.1/n—--—-—---—--—--—-—- (ul) As per the definition equation (1) = (I!) WLg. (-WLg.1/n = WE g+WEg 1/n Scanned with CamScannerWL-WE = WE.1/n + WL.1/n ((WL-WE) = 2/n (WE+WL) n= (WL+WE)/ ((WL-WE) Drawbar Pull: This is that part of the Tractive force which remains available for pulling connected load, hence drawbar pull can be calculated after deducting from the total Tractive force, the Tractive force required to haul the locomotive itself. ‘TF=TM Wloco = kg TF=TM Wloco. g =N TM= Coefficient of adhesion Force = mass X acceleration (TF+GL+FL=mass X acceleration. C) Conveyor system of haulage 1) Belt conveyor 2) Chain conveyor 1) Belt conveyor The belt conveyor is basically an endless belt in a straight line stretched between two drums, one driving the system and the other acting as a return drum. In coal mines and other mines of stratified deposits, where the underground mineral if won by longwall method, the transport media which often consists of conveyor. Scanned with CamScannerA (7. - SVAN HAUAAGE TO PIT BOTTOM Layout of face, gate and trunk conveyors ina coal mine ‘The system of transport by belt conveyor consists of the following: 1.A flat endless belt which moves continuously and carries at its top surface the material to be conveyed. 2. The idlers which support the belt. 3. The structure of channel iron on which the idlers are mounted. 4. The tensioning arrangement for keeping the belt in proper tension. 5. The drums at the discharge and tail end over which the belt passes. 6. The drive head which comprises the electric motor, coupling, gearing and snub pulleys Scanned with CamScannerCross-section of belt for conveyor system Selection of belt conveyor: 1, Amount of material to be conveyed 2. Continuity of operation needed 3. Size of lumps 4. Distance of transportation 5. Environmental allowance 6.Gradient 7. Method of coal winning, i.e. Longwall or Bord and Pillar Scanned with CamScanner8. Capital Available Advantages: 1.A continuous supply of material. 2. Low operating cost than road transportation system. 3. High rate and speed of supply. 4. Bunding can be done to get fair grade. 5. More efficiency and low cost. Limitations: Belt convey 1. Cannot be used for long distances 2. Required high one time capital 3. Lumps should not be of big size. 4.Place should be dry enough and air velocity should not be high 5. Cannot be worked for high inclinations Factors for designing of belt conveyor: 1. The average tonnage (t/h), peak rate (t/min) and frequency of peak rates. 2. Characteristics of the material i.e. density, maximum lump size, nature of material-dry, wet, sticky, dusty, chemical action on belt. 3. Graphical layout of conveyor profile and motive power available (i.e. electric motor). 4. Operating conditions - hours of working, climatic conditions etc. 5. Suitability ofa belt conveyor & width and speed of belt Scanned with CamScanner6. Belt shape. 7. Power and layout required. Take- up arrangements (Tensioning device): Tensioning of the belt is necessary to prevent excessive sagging of the belt or belt in good contact with the driving drum. 1. Automatic take ups 2. Gravity take ups. 3. Take up pulley with counter weight. 4. Counter weighted loop take. 5. Counter weighted wheel mounted tail end pulley 6. Power take ups 7. Electric motorized winch and load cell loop take up. 8. Pneumatically operated take up 9. Hydraulically loop takes up. 10. Rigid or manual take ups 11. Screw take up 12. Jack take up 13. Winch take up Scanned with CamScannerpulley _ Driving Arrangement of a drive motor, loop take-up and tensioning weights on a belt conveyor discharging downhill uphill conveying) Arrangement of a driving gear and loop take- up for a belt conveyor on level or uphill 2) Chain conveyor Itis mostly used in the longwall face. The capacity of a commonly used scraper chain conveyor is 30 to 40 tph ona level roadway, nearly SO m long and the drive motor is of 12- 15 KW. The main application of scraper chain conveyors in Scanned with CamScannerunderground is transportation at the face and adjoining short workings, where they are ready to withstand mining condition. They are also used to haul the coal along gate roads over short distances before it is feed to gate belt conveyor. They are also used for transporting on inclines having an angle of inclination exceeding 180 where belt conveyors are not used. They are also used on the surface for Conveying coal from shaft to bunker as well as inscreening and washing plants. Scraper chain conveyor Different parts: 1. Trough: These arestationary things usually 2m long, and consisting of detachable section bolted together or joined by hooks, 2. Flights: An endless chain with flights movingin the troughs, which arenearly 450 mm wide at top and 300 mm at bottom. 3. Chain (endless): The chain of endless character is installed there. The chain consists of links and after 3-4 links a flightis provided so, that the flights are 2- 2.Sm apart. 4, Tensioning head: The return or, tail end of the conveyor with its totally enclosed sprocket drum, is provided with telescopic trough by which the tension of the chain can be adjusted through Sylvesterchain 5. Drive: For enabling movement a power arrangement with driving arrangement. Scanned with CamScanner6. Angle iron frame: to supportthe troughs. Types: On the basis of flexibility— 1. Rigid chain conveyor 2. Flexible / armoured chain conveyor On the basis of number of chains used — 1. Single chainconveyor 2. Double centered chain conveyor 3. Double outboard chain conveyor 4. Triple chain conveyor Rigid chain conveyor: A rigid chain conveyor essentially consists of stationary steel troughs, each usually 2m long, connected together end to end, and an endless chain with flights movingin the troughs. Troughs supported on angle iron frame work, slightly dished at one end. So, that the next one fixed in to forma flush point. Adjacent troughs are secured together and to the frame underway by both. This gives rigidity to conveyor. The return end is provided with a tensioning arrangement. The capacity is 30- 40 tph on a level roadway, nearly 50m long and 15KWmotor. Armoured chain conveyor: Used generally on long wall faces, it canbe advanced without dismantling, with hydraulic rams. They can work with lateral or, vertical undulations, and coal cutting machine and shearers can be mounted on them. Motor power varies between 30 to 185 KW.Pan width at top varies from 750 to 850mm and pan length from 1.3 to 1.8m. the vertical flexibility of pansis 3-40 and horizontal flexibility is 2-30.Limiting gradient with flights 1 in 1.5 and without flights 1 in 3.Length may be upto 360 mand capacity is upto 100 tph. Advantages: Scanned with CamScanner1.Can convey uphill against relatively steep (1 in 3 or more) gradient as well as of downhill gradient. 2. Much stronger and can be roughly handled. 3. Flexible so, asto dismantle, extended or shortened. Disadvantages: 1. High initial cost. 2. High power consumption 3. Wear and tear more 4. Highly noisy 5. Producing high percentage of fine dust D) Aerial ropeway An aerial ropeway is an installation in which transportation of material or men is effected by moving carriers pulled by ropes suspended above the ground. Types: On the basis of number of ropes and the mode of transportation, the ropeways are classified as: 1)Mono-cable Ropeway- the ropeway has a single running endless rope which both support and moves the carriers. 2) Bi-cable Ropeway- the ropeway has two fixed track ropes along which the carriers are hauled by an endless traction rope. 3) Twin-cable Ropeway- the ropeway has two pairs of track ropes to support the carriers and one endless traction rope. Applicability Scanned with CamScannerAerial ropeway provides the only economic means of lang distance transport over rough country, hilly and difficult terrain, even it can pass through the congested areas, marshy lands, nallahs, rivers, forests and important agricultural land. Aerial ropeways have found wide application in: 1)Transporting and conveying bulk materials between two fixed pts. 2)Aerial dumping of load at any point along the line of route 3)Stocking of materials 4)Dumping of waste materials 5)Transporting of persons in mountainous regions Advantages: 1)Arelatively high transport capacity (upto 500 t/hr) 2) Regularity of service and immunity to all weathers 3)Ability to overcome natural obstructions (rivers, marshy ground etc.) 4)Inherent ability to keep the ground free for other purposes 5) Ability of negotiating steep gradient (70% and over) 6) Possibility of using automation 7) Minimum time lost in transportation 8) Low initial and operating cost and short time for returnon capital Disadvantages: 1)Fixed location of loading station 2) Susceptibility to damage by string winds. 3) The length of the line and transport capacity is limited by economic and technical consideration. Scanned with CamScannerBi-cable Ropeway It has following components: 1. Two track ropes or cables stretched at required tension 2. An endless traction rope for handling the loads, 3. Carriers suspended from the track ropes and hauled by the traction rope 4.Machinery and other arrangements for loading and unloading carriers, suspending the track ropes and driving the traction rope. CARRYING ROPES way TENSION we oaive s ARRANGEMENT OF A BICABLE ROPEWAY WITH A CONTINUSLY CIRCULATING ROPE LOCKING FRAME 10. UNLOCKING OF CARS Bi-cable Ariel ropeway Scope of applicability and Limitations a.Bi-cable ropeways are suitable for capacities 100 to 400 Yhr. b. lengths up to 6 kmin one section of traction rope. c. For capacities less than 100 t/nr. and distances less than 300 m, bi-cable ropeway cannot providethe desirable economy. Scanned with CamScannerDifferent parts Ropes: Track ropes: 1.Track ropes are usually locked coil ropes made of large size wires in order to have longer life. 2. Locked coil ropes provide a smooth surfacefor the movement of carrier wheel and the surface wear of it is relatively uniform. 3. The factor of safety for track rope during installation should be 3 and must be withdrawn from service when it reduces to 2.5. 4. Average life of the rope is 5 to 7 years. ‘Traction rope: Traction ropes are Six-strand lang’ slay with fibre core. The rope diameter varies from 12 to 46 mm. The factor of safety should be S during installation and ropes should be withdrawn when it comes downto 4. Carriers: A carrier has the carriage, hanger, bucket and grip for traction rope. Carriage runs on track rope with wheels, and it runs onthe track rope, with the help of wheels (20 — 30 cm/diameter) mounted on it. The number of wheel is 2 for light loads and 4 for medium or heavy loads. The hanger is suspended from carriage to make its axis vertical. The bucket is supported by the hanger and grip on carriage. Three types of carriers are commonly used namely rotating carrier, bottom discharge carrier and fully enclosed bucket. Scanned with CamScannerCarrier of bi-cable ropeway Trestles: The trestles for bi-cable ropeways provide supportto both the track and traction ropes. As well as giving necessary profileto the ropeway. The track ropes rest onthe saddles at the top crossbeam and the traction rope on the sheaves at the cross beam below. Trestles are constructed either in steel, reinforced concrete / timber. The height of the trestles is usually in the shape ofa truncated pyramid. The ht. of the trestles is usually 8 to 12 mon level groundand spaced at intervals of 100-250 m. Butin a mountainous region, they must be as high as 100 mand spaced at 500 mor more. The trestles should be erected on firm ground. Scanned with CamScannerSteel trestles ofa Bi-cable aerial ropeway Saddles: These are rolled steel section bent along their longitudinal central line to allow rope curvature on the support. The upper part of the saddle is grooved to accommodate and support the track rope. For safety against unloading of the rope, the groove dia, should be 1.5 d and the depth of the groove 0.8d, whered is the diameter of the rope. Stations: Loading station: Station where carriers are loaded are called loading station and in bi-cable ropeway it is morecomplicated than mono cable ropeway. Atthe loading stations, the track rope tensioning device is avoided and the end of it is anchored instead. Howeverthe tensioning of the traction rope may be incor porated. At the entry to station, the carrier leaves the track ropeand rides on the station rail and while leaving it, rides back on the rope. To facilitate those, rope deflecting saddles are put at the transition point. The carriers passes through Scanned with CamScannerthe arrangement of releasing and gripping of the traction rope movement of the carrieris controlled manually or by running chain at automatic station. Unloading station: Itis the discharged end of the rope way. The unloading station should be sufficiently high enough above the ground level to make possible unloading by gravity. Intermediate station: Whena bi-cable ropeway has morethanone section, intermediate stations are provided where it passes from one section to another. Arrangements are there for tensioning. Angle station: When it is not possibleto take a straight line route, angle station are provided to change the direction of route. Here the track ropes of adjacent arms terminate by means of anchorage or tensioning arrangement. Scanned with CamScanner