Truck and shovel operation make up the majority of the surface operations worldwide, this is also the case here in Australia. However, considering high workforce cost and high focus on safety, one would expect the use of conveying systems to be a more popular option in Australia.
Both conveying and trucking systems have their advantages and disadvantages, below is a summary;
Advantages Conveying
- Lower energy consumption (when elevating material)
- Possible energy generation (when lowering material)
- Smaller Workforce required to operate
- Easier to automated
- High capacity
- Low operating cost
- Safe
Disadvantages Conveying
- High upfront capital cost
- Max particle size limited by belt
- Only accepts fragmented material (in pit crushing might be required)
- Inflexible
Advantages Trucking
- Lower upfront capital cost
- Accepts poorly fragmented material
- Very flexible
Disadvantages Trucking
- High energy consumption (caused by empty vehicle mass)
- Large workforce required
- Difficult to automate
- Unsafe (approximately 1 in 3 accidents in surface mines are vehicle related)
- High operating cost
High upfront capital costs is the most obvious reason for the unpopularity of in pit conveying systems. However, over the life of mine; especially for larger operations, the total capital cost for conveying systems will be lower than that of a conventional truck and shovel systems. This is caused by the relative short economic life of trucks and shovels, compared to conveyor systems which can generally be kept operational provided components like idlers, belts, drivers etc; are replaced as part of ongoing maintenance.
Inflexibility of conveying systems also attributes to their unpopularity, to overcome this detailed upfront planning and exploration is required to operate a conveying system effectively. The use of conveyor bridges and mobile modular conveyers can increase the flexibility of a conveying system. The increased focus on planning may require a change in the management approach and may not always be well understood.