Heap leach performance depends on more than metallurgy and irrigation. Before solution is applied, the ore must be prepared, transferred and placed in a manner that supports permeability, stability and operational efficiency. This combination of ore preparation and material handling is often referred to as the heap leach stacking system.
What is a heap leach stacking system?
A heap leach stacking system is the collection of equipment used to move conditioned ore from the preparation stage to final placement on the heap leach pad. Modern systems are designed to maintain continuous material flow while allowing the heap to advance, expand or retreat as operations progress.
A typical system includes:
- Ore preparation and, where required, agglomeration
- Ramp Conveyor
- Grasshopper Conveyor string
- Transverse Conveyor
- Horizontal Index Conveyor
- Radial Stacker
Why stacking systems matter
The stacking system influences:
- Ore placement
- Segregation behaviour
- Heap geometry
- Operational flexibility
- Equipment utilisation
- Access to future lift development
The objective is not simply to move ore. The objective is to place ore consistently while supporting long-term heap performance.
The material handling sequence
Agglomeration
Where required, ore is conditioned to bind fines to larger particles and support permeability.
Ramp Conveyor
Provides transfer across changes in elevation or ramped approaches.
Grasshopper Conveyors
Form the mobile transfer string across the pad.
Transverse Conveyor
Provides the handoff between the Grasshopper string and
Horizontal Index Conveyor
.Horizontal Index ConveyorActs as a mobile bridge conveyor during retreat stacking operations.
Radial Stacker
Places ore across the heap and creates the required stacking profile.
Advance stacking versus retreat stacking
Two common stacking approaches are used:
Advance stacking moves progressively forward as ore is placed.
Retreat stacking places ore while the stacking system retreats across the pad.
Many large heap leach operations favour retreat stacking because it integrates effectively with mobile conveyor arrangements and expanding heap geometry.
Why mobile systems are common
Mobile conveyor systems provide flexibility as the heap develops over time. Equipment can be relocated, repositioned and reconfigured without constructing entirely new fixed infrastructure.
Potential advantages include:
- Reduced dependence on truck haulage at the active placement face
- Flexible pad development
- Continuous ore flow
- Compatibility with multiple lift strategies
Key design considerations
Designers typically evaluate:
- Ore characteristics
- Throughput requirements
- Pad geometry
- Lift heights
- Stacking strategy
- Mobility requirements
- Irrigation philosophy
No single stacking arrangement is suitable for every project.
Frequently Asked Questions
Here are some common questions we get asked at Carmaky.
What is a heap leach stacking system?
A collection of conveyors and stackers used to move ore from preparation through final placement on the heap leach pad.
What equipment is used in a heap leach stacking system?
Ramp Conveyors, Grasshopper Conveyors, Transverse Conveyors, Horizontal Index Conveyors and Radial Stackers are common components.
What is retreat stacking?
A stacking method where the equipment progressively retreats while maintaining ore placement.
Why are mobile conveyors used?
They provide flexibility as pads expand and operating conditions change.
Conclusion
Heap leach stacking systems form the connection between ore preparation and metal recovery. The design of the material handling system influences ore placement, operational flexibility and the ability to build and expand leach pads efficiently. Understanding how each piece of equipment contributes to the overall process helps operators and project teams select a configuration aligned with their production and development objectives.
Related resources: heap leach stacking systems · Heap Leach Resource Centre