​​ ENMIN 5140 Materials Handling and Hoisting Course Question Sheet 1) A Shuttle car travels at an average velocity of 1.5 m/s from a loading machine to a conveyor belt where it will discharge its payload. If the travel time is 70 seconds, what will be the distance between the loading point and the dump? 2) If a surface haulage truck accelerates at a uniform rate of 0.2m/s 2 from rest, what will be its velocity after 25 seconds? 3) A 20 tonne mine locomotive is travelling at 45 km/hr. Determine the retarding force of the brakes required to stop it in 250m on a level track. 4) A mine utilises a 60 tonne locomotive. On clean dry rails the adhesion factor is 0.2 for braking. In these circumstances what is the tractive effort in kg? 5) For the locomotive in question 4, if the locomotive resistance is 14 kg/tonne determine the drawbar pull. 6) An open-pit copper mine uses one 19 m 3 loading shovel to load 170 tonne capacity haulage trucks. Usually it takes four passes with the shovel (cycle time: 40 s per pass) to load each truck. The average load per truck is 61.2 m 3 . The copper ore has a density of 2258 kg/m 3 (bank), and the ore has a swell factor of 0.67. The following times have been projected: haul time, 18 min; spot time, 0.5 min; dump time, 1.0 min; return time, 12 min. determine the production in tonnes per hour for each truck. 7) An evacuation hoist is to be installed for an underground coalmine. The vertical hoist will evacuate 5 miners at one time every 4 minutes. The depth of the overburden is 200 m. Determine if a 0.625 in 6 x 19- haulage rope would be adequate for this application? The following may be assumed, the escape capsule weighs 907.2 kg, the total weight of the miners is 680.3 kg and the maximum rope velocity is 1.524 m/s. For the rope the weight per m of rope is 0.1 kg/m, minimum factor of safety for man riding is 9, breaking strength is 11287 kg. 8) For a hoisting system with a 3 period Trapezoidal speed time diagram determine the hoisting capacity of a shaft if the skip payload is 22 tonnes, hoisting distance is 800m, maximum rope speed is 10 m/s, acceleration and deceleration are 1.5 m/s 2 and the rest time between winds is 10 s. 9) For the following winding conditions determine if a rope with a minimum breaking force of 10 MN gives a satisfactory factor of safety for the winding of ore? Depth of wind = 850m Mass of skip and attachments = 15 tonne Mass of ore wound per wind = 22 tonne 1 Mass of rope/100m = 750 kg/100m Note for ore hoisting using a drum winder minimum factor of safety = 7.0 10) A 70 tonne locomotive is used to haul coal from a loading sidetrack to an unloading centre 2000m distant. The trips are designed to accelerate at a rate of 0.24 kphps on a level grade. If 10 tonne capacity cars with a tare weight of 5 tonnes are used. Determine the number of locomotives required to haul a shift tonnage of 7000 tonnes. It can be assumed that the locomotives average a speed of 16 kph with a 5 minute turnaround at each end . Roller bearings are used throughout and an adhesive factor of 25% is to be used. Operating time per shift is 8 hours. 11) Determine the size of locomotive required to pull a 400 tonne train from a level siding at a maximum acceleration of 0.3 kphps if antifriction bearings with an F = 0.1 kg/tonne are used on all equipment. An adhesive factor of 25% should be used. 12) For the locomotive in problem 11, determine the maximum grade against which the locomotive can pull the train without decelerating, using the same adhesive factor. 13) For the situation in problem 12, if the adhesive factor is 35% what is the maximum grade the locomotive can pull the train without decelerating? 14) Design a conveyor belt to haul mineral, density 1200 kg/loose m 3 , 1500 m on the level in an underground mine. Peak capacity is to be 2500 tonne/hr, belt speed is advised to be 4 m/s. Assume that the drive has automatic take-up, lagged pulley and a 270° arc of contact. Motor drive efficiency is 0.83. 15) Design a conveyor belt for the same situation as problem 17, except the belt is hauling the coal up a 10° slope whose slope distance is 1507.5m. 16) Two 5 tonne shuttle cars operate at an average speed of 2 m/s during the development phase of a panel. The loading machine has a rate of 2.5 tonnes/min. loader/ change out distance is 30m. If each shuttle car incurs a wait at the change out point of 0.5 min and the shuttle car discharge time is 0.45 min what is the haul distance from the change out point to the dumping point? 17) Estimate the cycle time and production of a 72 tonne GVW off highway truck with 41 tonnes on its rear wheels when loaded to its rated capacity, operating on a level haul road of 1500m length. The road is a rutted dirt roadway with no maintenance and no stabilisation, tyre penetration is 3 cm. The following can be assumed; a) Loading time 1.4 min b) Manoeuvre and dump time 0.8 min c) Truck hauls 40 tonnes of ore each trip d) Job efficiency of 0.8 18) For the situation in question 17, determine the cycle time if road conditions were improved to a rolling resistance of 20 kg/tonne. 19) For the problem in question 18 the engineer at the site is considering the use of a shorter, 1000m, haul road that has a slope of 4% adverse. If all other factors remain the same which haul route should be selected on the 2 basis of shortest cycle times? What are the cycle times and hourly productions? 20) For a standard load haul dump situation drawing ore from an open stope and dumping to an ore pass, describe the factors that make up the cycle time for the unit. Also to achieve a desired production rate detail the method you would use to select the required bucket size and number of units to be used. 21) What is the difference between a drum hoist winding system and a koepe winding system? What factors influence the application of each system? 22) In a conveying system what is the impact of changing the troughing angle of the conveyor?. 23) What guide arrangements can be employed in a shaft winding system and why are guiding systems required? Describe one method of guiding in greater detail. 24) What type of unloading arrangements are there for skips in a shaft hoisting system?. 25) What factors should be taken into account when selecting an excavatorl for an open pit mining operation? 26) A shaft winding system is made up of a number of principal components, list each of these. 27) Discuss the relative advantages and disadvantages of rubber tyred and tracked machinery for earthmoving. 28) An off highway truck weighs 23 t empty and carts a payload of 35 t up a 6% grade. The RR factor is 50 kg/tonne. Calculate: a) The total resistance (kg) b) The effective grade (%) 29) a rubber tyred scraper unit weighing 50 t is towed by a crawler tractor weighing 40t up a 6% grade. The RR factor is 40kg/t. Calculate: a) The rolling resistance (kg) b) The grade resistance (kg) c) The total resistance (kg) 30) A Caterpillar D30D articulated dump truck has the rim pull curve in figure 1. (Gross weight 21.9 t empty, 49.117 t loaded). If the truck ascends a 7% grade with a rolling resistance of 40 kg/t, find the following: a) Total resistance (kg) b) The required rim pull (kg) when loaded c) The maximum speed of the truck when loaded (km/h)