MATERIAL HANDLING 2011 CHAPTER 1 INTRODUCTION 1.1 PROBLEM DEFINITION SHOVEL TRUCK HAULAGE Tarkwa Rocky Gold Mining Company is proposing to develop a new open pit mine. Overburden will initially be removed by scraper and is therefore not the subject of this problem. The remaining oxidised ore must be drilled, blasted and transported to a crusher dump point, where it will be dumped for a front-end- loader to rehandle into the crusher. The anticipated haul profile for the first five years is given in Table 1. Speed limit is 44 kmph. Table 1 Haul Profile from Mining Face to Crusher Haul Segment Length (ft) Rolling Grade (%) Remarks Resistance (%) 1 400 (122m) 3 0 Pit Bottom 2 1700 (518.2m) 2 8 3 800 (243.8m) 4 3 4 2800 (853.4m) 2.5 8 5 900 (274.3m) 3 8 6 1600 (487.7m) 3.5 -2 7 300 (91m) 4 0 Crusher Approach 8500 1 MINI PROJECT GROUP 12
To determine the shovel model (size) and the truck model (size) and the corresponding shovel and truck fleets that will be required to meet production target, taking into consideration both technical and economic factors.
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MATERIAL HANDLING 2011
CHAPTER 1
INTRODUCTION
1.1 PROBLEM DEFINITION
SHOVEL TRUCK HAULAGE
Tarkwa Rocky Gold Mining Company is proposing to develop a new open pit mine. Overburden will initially be removed by scraper and is therefore not the subject of this problem. The remaining oxidised ore must be drilled, blasted and transported to a crusher dump point, where it will be dumped for a front-end-loader to rehandle into the crusher. The anticipated haul profile for the first five years is given in Table 1. Speed limit is 44 kmph.
The ore material is quite hard and fragments badly upon blasting and therefore management has recommended the use of diesel powered hydraulic front shovels for the excavation. However, the best shovel (model) is to be investigated and selected. Since Tarkwa Rocky Gold Mine has got a long-standing relationship with Caterpillar, it intends to consider only Caterpillar shovels. They are considering two models of hydraulic shovels. Table 2 presents some details on the shovels and their specifications.
Table 2 Shovel Data Model 5110 5130Bucket Capacity 7.8 m3 9.5m3
The loose density of blasted ore = 2.2t/m3 (141.63 lb/ft3)Material swell = 20%Size range = Run-of-mineClimate = TropicalAltitude = 200m (656ft)Quantity of material to be hauled per year = 12000000 tonnes
The company is considering a selection of two types of rear dump trucks manufactured by Euclid: EUR50C (50 ton capacity), EUR100C (100 ton capacity)
Table 3 presents data on each of these trucks.
Table 3 Data on Trucks
Truck Type EUR100C EUR50CManoeuvre and Dump time (min) 1.2 1.0Spot time (min) 0.55 0.45Availability 0.87 0.87Economic life (hr) 30000 30000
1. Determine the shovel model (size) and truck model (size) and the corresponding shovel and truck fleets that will be required to meet production target, taking into consideration both technical and economic factors.
Make assumptions where necessary, justify your assumptions. Make use of the Terex Vehicle performance and retarder charts and speed factors.
2. Present your results in the form of a report Each member of a group should actively participate in the work. This will be ascertained
during an oral defense at the end of the semester. Make use of all recommended textbooks and class notes. Consult lecturer for clarification
when necessary.
1.2 OBJECTIVES OF PROJECTTo determine the shovel model (size) and the truck model (size) and the corresponding shovel and truck fleets that will be required to meet production target, taking into consideration both technical and economic factors.
1.3 SCOPE OF WORKThis project work is limited to the process involved in the selection of Model Trucks and caterpillar Shovels for the most economic and optimum production of Gold at Rocky Gold Mining Company, Tarkwa.
2MINI PROJECT GROUP 12
MATERIAL HANDLING 2011
CHAPTER TWO
COMPARING ECONOMIC LIFE OF EACH SHOVELWITH THE ANTICIPATED HOURS OF THE MINE.
Anticipated years of operation = 5 years
Number of days of working = 304 days
(Taking into consideration 52 Sundays of not working plus 10days considered as holidays by management)٭
Number of effective hours of working per day = 21 hours (One hour delays for each of the 3 shifts)
Quantity of material to be hauled per year = 12000000 tonnes
Quantity of material to be hauled per day = 12000000
304 = 39473.68 tonnes / day
Quantity of material to be hauled per hour =39473.68
21 = 1879.70 t/hr
Number of hours the shovel would be put to work in a day = 20 hrs ٭
Number of hours the shovel would be put to work in a year = 20× 300 = 6000 hrs
Number of hours the shovel would be put to work in five years = 6000× 5 = 30000 hrs
From our result above, it is clearly seen that it is not advisable to go in for the shovel model 5110 unless two of them is to be purchased since it has a lesser economic life hours (25000 hrs) than -anticipated.
However, this may not warrant rejection since it may make it up for the other factors of much importance.
Please note: all remarks with symbol ٭ are assumptions.
3MINI PROJECT GROUP 12
MATERIAL HANDLING 2011
2.1 Considering Truck Model EUR 100C
Travel Time
Truck gradeability when loaded:
Gradeability = GrossVehicle Weight (GVW )
Horse Power( Hp)
= 3489001050
= 332.29 1bs/hp
This lies between 300 – 380 1bs/hp
2.2 Travel Time
Table 2.1 Travel Time When Loaded
Haul Seg. Length in (ft). RR (%) GR (%) TR (%) Max Vel.(Km/hr)
Please Note; The original Mean Vel. of haul segments; 6, 5, 4 and 2 are 54.0km/hr (15.00m/s), 46 .98km/hr (13.05m/s), 55.68km/hr (15.47m/s) and 52.78km/hr (14.66m/s) respectively but have been reduced to 44km/hr which is the speed limit.
Some of the interpolations made:
S.F of haul seg 7 = 400−201300−201 =0.51−0.40
x−0.40
x=0.45
Total Travel Time = 502.83 + 220.02
= 722.85 seconds
= 12.04 minutes
3.3 Cycle Time with Shovel Model 5110
12MINI PROJECT GROUP 12
MATERIAL HANDLING 2011Cycle Time = Spot & Load Time + Travel Time + Turn & dump Time
For The Spot and Load time Payload of Truck (50c) = 50 ton
= 100,000 lbs
Tonnage per pass = dipper volume x loose density x (Assumed) fill factor = 7.8m3 x 2.2t/m3 x 0.9 = 15.44 t = 34029.76 lbs
Number of Pass, Pt = payload
tonnage / pass=¿
100,000lbs34029.76lbs
= 2.94
= 3 passes
Actual Payload of Truck = 3 x 15.44 t = 46.32 t
Spot Time = 0.45 min > shovel cycle Time = 0.43 min
Table 4.1.4 Calculated result on Truck EUR 50CType of Shovel Number of passes Tonnage per hour Number of shovels Number of truck to shovelModel 5110 3 164.62 1 11Model 5130 2 137.44 1 15
It is also observed that both Shovels satisfy the recommendation that three to six (3 to 6) passes
should fill truck except for Shovel Model 5110 when matched with Truck Model EUR100C.
From Table 4.1.3 and Table 4.1.4, Truck Model EUR100C is observed to check well with Shovel
Model 5130 and Truck Model EUR50C is observed to check well with Shovel Model 5130
respectively.
Table 4.1.5 Comparing EUR100C & 5130 with EUR50C & 5110
Selection FactorsNumber of
Passes
Tonnage per
Hour (t/hr)
Number of
Trucks
Number of
trucks to
Shovel
Shovel Capacity
And Economic
Life
EUR100C with
51305 287.05 8 6
9.5m3
40,000hrs
EUR50C with
51302 137.44 16 15
9.5m3
40,000hrs
From Table 4.1.5, it can be observed that considering the various selection factors considered
Shovel Model 5130 offers the highest hourly tonnage matched with Truck Model EUR100C with
a lower truck fleet (8 trucks) and this also checks well.
Since both trucks and shovels have the same shovel capacity, same number of shovels, the same
dipper volumes, then we consider the number of trucks for economic reasons.
18MINI PROJECT GROUP 12
MATERIAL HANDLING 20114.2 Conclusion
Based on the above observation, Shovel Model 5130 and Truck Model EUR100C have been
selected since this match gives;
Higher tonnage rate per hour
Reduced logistic trouble (less truck fleet)
4.3 Recommendations Berms and escape lanes should be provided to improved safety. Traffic signs should be postal for velocity limits stops and intersection warnings. To avoid road damage, appropriate drainage ditches should be constructed,
a curve, the necessary super – elevation should be constructed to counteract the effect of centrifugal forces.
FIG 4.1 A Picture of a truck loading under a shovel
References
19MINI PROJECT GROUP 12
MATERIAL HANDLING 2011Cummins A. & Given I. (1973): SME Mining Engineering Handbook, Vol. 1. Port City Press,
New York.
Temeng, V.A. (2010): Lecture Notes on Material Handling (Unpublished). University of Mines