Loading Equipment Comparison…..
Conclusions
1. Cable Shovels:
a. High capital cost (based on the dipper size)
b. Little mobility (low maneuverability)
c. Relatively high productivity (low cycle time)
2. Front End Loaders
a. High mobility: several loading sites feasible
b. Low initial cost (based on bucket size)
c. Relatively low productivity (cycle time)
Comparison, cont….
1. Selectivity of mining:
a. Cable shovel: bench = three dipper heights rule
b. Hydraulic shovel: bench = one bucket height
c. Hydraulic shovel: bucket positioning control
2. More selectivity has a measurable benefit
a. Less ore dilution, means:
b. Less material handling and processing
c. Higher recoveries and plant throughput
Conclusions
1. Cable shovels need high benches
a. Little selectivity
b. Bucket fill low on low benches
c. Need support equipment to clean bench floor
2. Hydraulic shovels & FELs can operate efficiently at low benches
a. High selectivity
b. Limited ability to clean pit floor
Comparison, cont…..
1. Cable shovels: two dipper movements:
a. hoist and push (forces fighting each other)
b. eg. “raking” action of dipper
2. Hydraulic shovels and FELs: three bucket movements:
a. lift, push and twist
b. eg. bucket movement in three dimensions
3. Hydraulic shovels:
a. backhoe vs. front-end attachment
Conclusions
1. Cable shovel requires well blasted material
2. Hydraulic shovel (and FEL?) can handle poorly shot material
3. Hydraulic shovel has very high selectivity
4. Hydraulic shovel has high digging forces
5. Backhoe can work from the top of the bench
pit bottom problems, very high selectivity
Comparison, cont…..
1. Dimensions:
a. Cable shovels are large (mass, dimensions)
b. Existing front end loaders are small
2. Conclusions:
a. FEL has problem with loading large trucks
3. Undercarriage:
a. FEL mounted on tires: rocks hurt
Cable Shovel Applications
1. A 15 year or longer mine life
2. A 30 ft ( 10 m) or higher mining benches
3. Solid, level floor
4. Fairly well blasted material
5. Adequate and cheap electric power
6. Minimal movement
7. Clean-up support equipment required
Hydraulic Shovel / Backhoe Applications
1. Hard digging
2. Poorly shot material
3. Selective loading / excavation
4. Wet, jagged, uneven floor
5. Pitching floor
6. Single face operation
Wheel Loader Applications
1. Mobility and versatility
2. Well fragmented material
3. Low pile profile
4. Smooth, level floor
5. No clean-up support equipment
Summary
Electric shovel and mass excavator
well blasted material, high benches, little mobility, low unit operating cost
Hydraulic shovel and selective excavator
highest digging forces, high selectivity (low benches)
Front end loader and loading tool
high mobility, low piles, reasonable selectivity, low digging forces