Developments in Heap Leaching as a Technology Choice for Value Extraction from Primary and Secondary Resources

Heap leaching is part of the group of “percolation leaching” processes that selectively remove metal values from an ore into a suitable aqueous leaching agent that seeps through a pile or mass of the ore. It has become well-established technology choice for the treatment of low-grade copper and gold ores and is also practiced for uranium ores and REE recovery from ion adsorption clays. Various other applications (Zn, Ni, PGMs) have been explored but not reached commercial significance as yet. 

Apart from the different chemistries and mineralogies, all these applications operate on very similar principles, which will be laid out in some detail in a keynote from Prof. Jochen Petersen, of the University of Cape Town, at Hydrometallurgy '27.

Selection of heap leaching as process technology is primarily driven by its ability to extract value from low-grade materials, as the need for high capital and operating expenditures, especially for intensive comminution processes to produce a concentrate material for further processing, is avoided. However, the relatively long time required to recover the metal value from larger particles, with overall poorer metal extraction achieved, imposes certain economic penalties which have resulted in heap leaching remaining limited to low-grade ores.

Nonetheless, ever-increasing energy costs and awareness of the associated carbon footprint have recently led to a re-evaluation of the technology for primary ores. At the same time the drive towards resource efficiency and the attainment of circular economies for many metals has also opened significant opportunities for the heap leaching of tailings and waste materials and thus a re-evaluation of the technology. Some examples of these developments will be discussed in Jochen's presentation.

Jochen holds a PhD in Chemical Engineering from the University of Cape Town, where he is now Full Professor after a research career spanning close on 30 years in hydrometallurgy. His research covers leaching and recovery of Cu, Ni, Zn, PGMs, Au and REEs from both primary minerals and secondary resources such as e-waste. His key field of expertise is heap leaching.

Jochen has co-authored over 150 peer-reviewed journal and conference papers and supervised 15 PhDs and 60 MScs to graduation. He was the Editor-in-Chief of the journal Hydrometallurgy 2011-2021 and held a prestigious South African Research Chair 2018-2022.

Jochen at Biohydrometallurgy '10 in Cape Town after
being appointed the new co-editor of Hydrometallurgy.
 He is with Dean Eastbury, his publishing manager at Elsevier

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