When people first encounter heap leaching, they are often confronted by specialised terminology covering metallurgy, hydrology, geotechnical engineering and material handling. Understanding these terms improves communication between mine operators, engineers, metallurgists, project teams and equipment suppliers.
This article explains the most important heap leach terms and provides a downloadable terminology guide.
Why terminology matters
Heap leaching combines mining, crushing, agglomeration, conveying, stacking, irrigation and metallurgical recovery. Misunderstanding a technical term can result in confusion during project development, equipment selection and operational planning.
Key Terms Every Heap Leach Professional Should Know
Agglomeration
The process of combining fine particles with moisture and, where required, a binder to form larger, more permeable aggregates.
Agglomeration Drum
A rotating drum used to mix ore, moisture and binders prior to stacking.
Heap Leaching
A hydrometallurgical process where ore is stacked on a lined facility and irrigated with a solution that dissolves valuable metals.
Dump Leaching
A leaching method using largely uncrushed run-of-mine material, generally with lower cost but slower extraction and lower recovery potential.
Permeability
The ability of ore to allow solution flow through the heap. Permeability is one of the most important factors influencing heap performance.
Percolation
Downward solution movement through the heap after irrigation.
Pregnant Leach Solution (PLS)
The metal-bearing solution collected from the heap after leaching.
Raffinate
Solution returned to the heap after metal recovery.
Lixiviant
The chemical solution used to dissolve valuable metals from ore.
SX/EW
Solvent Extraction and Electrowinning, commonly used in copper recovery circuits.
Grasshopper Conveyor
A mobile transfer conveyor used to move ore through a stacking system.
Transverse Conveyor
A transfer conveyor feeding material toward the placement equipment.
Horizontal Index Conveyor
A tracked bridge conveyor used in retreat stacking systems.
Radial Stacker
The final placement machine used to distribute ore across the heap.
Leach Pad
The engineered structure where ore is stacked and irrigated.
Lift
A layer of ore placed during heap development.
Cell
A defined operating section within a leach facility.
Most searched heap leach terms
Based on industry usage, several topics are searched more frequently than others:
- Agglomeration
- Heap Leaching
- Dump Leaching
- PLS
- SX/EW
- Permeability
- Percolation
- Raffinate
- Leach Pad
- Radial Stacker
Download the Complete Terminology Guide
For a more comprehensive list of heap leach terminology, including over sixty industry terms covering metallurgy, process operations and heap construction, download the Carmaky guide.
Frequently Asked Questions
Here are some common questions we get asked at Carmaky.
What is PLS?
Pregnant Leach Solution is the solution containing dissolved metals collected from the heap.
What is the difference between permeability and percolation?
Permeability describes the ore's ability to allow flow, while percolation describes the movement of solution through that ore.
Why is agglomeration important?
Agglomeration may help maintain permeability and reduce fines migration in suitable ores.
What does SX/EW stand for?
Solvent Extraction and Electrowinning.
Conclusion
Understanding heap leach terminology creates a common language for project development, operations and equipment selection. As heap leach projects become larger and more integrated, clear communication between technical disciplines becomes increasingly important.
Related resources: heap leach stacking systems · Heap Leach Resource Centre