With heap leaching, the only preparation required is crushing and agglomeration prior to stacking of the ore onto the pad. For a more elaborate system to recover the intended mineral, crushing and milling would be required. The milling aspect is energy intensive and requires expensive equipment. With fewer steps in the preparation process, heap leaching also offers major time efficiencies and reduced operating costs.

Since the early 1990s, SENET has delivered leading engineering, procurement, and construction/construction management (EPC/EPCM) contractors for entire heap leach plants. This offering evolved from its initial development of a range of proprietary Heap Leach Stacking and Agglomeration Equipment.

So how has SENET evolved from an equipment supplier to an expert in heap leaching – all while maintaining its position of global success for more that 30 years?

According to Philemon Bundo, Senior Vice President- Process at SENET, a DRA Global Group Company, this success lies in a dedication to catering to each client’s specific requirements, while fostering ever improving heap leach capabilities across the board.

Why Choose Heap Leaching?

Bundo confirms that heap leaching is the process of choice when the metal content in the ore is sufficiently oxidised to warrant heap leaching. It offers a highly profitable method to extract or beneficiate the metal. This method is mostly used for the extraction of Gold, Copper, Uranium, and Silver.

What Makes Heap Leaching So Cost Effective?

“The associated equipment and techniques employed to recover the metal from the ore through heap leaching is far more affordable than other more elaborate processes,” adds Bundo.

With heap leaching, the only preparation required is crushing and agglomeration prior to stacking of the ore onto the pad. For a more elaborate system to recover the intended mineral, crushing and milling would be required. The milling aspect is energy intensive and requires expensive equipment. With fewer steps in the preparation process, heap leaching also offers major time efficiencies and reduced operating costs.

A Steppingstone in the Establishment of Elaborate Mining Operations

Bundo notes that this approach can result in less metal being recovered than with other intricate processes. While heap leaching allows for the recovery of about 75 to 85% of the metals, more advanced processes recover between 90 and 95%.

“As a result, heap leaching is often used as a starter process for mining operations to generate sufficient income to implement more complex processes, which will result in a higher yield. As such, it offers the extraction of good enough quality metals to generate funds for reinvestment into more elaborate systems or the next phase of development.”

The Role of Labs and the Heap Leaching Process

 

“The whole process starts in the lab where we investigate whether a particular type of ore is amenable to heap leaching. Once that has been established, we take the required parameters into the design of a production plant,” confirms Bundo.

He adds that this is the point when the heap leaching process itself begins, in the following sequence:

  • Ore preparation by way of crushing
  • Where the ore contains a lot of fines, it is agglomerated to bind the fines to the coarse material (this ensures that when the solution is sprayed on the heaped ore, the solution can percolate through the ore)
  • The ore is then stacked into heaps
  • A solution containing chemicals to dissolve the metal is sprayed onto heaps (the type of chemical used depends on the metal being extracted)
  • The solution then percolates or runs down the heap, dissolving the metal
  • A collection system at the bottom collects the enriched solution which flows into a storage facility; usually a pond
  • The contents of the pond is then pumped into the next stage for further metal recovery

Then and Now: SENET’s Heap Leach Capabilities Continue to Grow

 

SENET’s first major installation was the 1,2 Mt/a plant at Cluff’s Ayanfuri gold mine in Ghana in 1994. “This was a proud moment for our team, being the first heap leach facility to be provided by any South African company,” concludes Bundo.

“Having started predominantly in Gold, today SENET’s heap leach expertise extends to large Copper projects within Africa and abroad; including the engineering, construction, and commissioning of the 25Kt/a copper cathode, Kipoi Heap Leach mine in the Democratic Republic of the Congo (DRC).”

For more information from SENET’s heap leach experts, contact Philemon Bundo (p.bundo@senet.co.za).

 

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