Some background...Heap Leach: Mining’s breakthrough...

Some background...

Heap Leach: Mining’s breakthrough technology

Amid turmoil on commodity markets and a relentless drive by mining companies to increase efficiencies, heap leaching has emerged as a breakthrough technology experiencing stunning growth over the past decade

Generally, the HL process involves the following steps:

1. Mine the ore
2. Crush the ore (if necessary)
3. Agglomerate the ore (if necessary)
4. Place the ore on a lined pad
5. Irrigate the ore with the appropriate lixiviant to dissolve the metals (leachate)
6. Collect the leachate in a pond or tank (pregnant or value bearing solution)
7. Process the pregnant solution to recover the metals
8. Recycle the barren solution (with additional lixiviant) back to the heap.

Figure 2. Simplified general HL scheme.

The main advantages of HL technology are, as follows:

• lower CAPEX and OPEX
• rapid payback
• no tailings disposal
• simple design and equipment
• less environmental concerns
• quick construction phase
• lower energy and water requirements
• applicable to low-grade ore, tailings and waste stockpiles

Trends in Heap Leaching

Due to abovementioned economic benefits, the number of HL operations has experienced an impressive and sustained growth over the last decades, with precious metal operations benefitting the most from the technology.

The recent commodity market downturn has spurred further commissioning of new HL projects throughout the world (Figure 3).

Figure 3. Start-up of currently operating major Heap Leach mines, # mines.Source:IntelligenceMine.

HL operations are located in wide variety of geographical conditions, and succeed in all types of climate, from the Arctic Circle to the Tropics.

According to theIntelligenceMine’s database, there are 235 active major HL operations worldwide, as well as 39 projects in development and 133 in evaluation phases (Figure 4).

Figure 4. HL projects by status and commodity.Source: IntelligenceMine.

Metal production from HL operations reached considerable proportions since their inception in the 1950s.

https://www.mining.com/heap-leach-minings-breakthrough-technology/