2009 – ALTA, Perth WA


The metallurgical heart of the majority of copper oxide processes is the heap leaching
operation. The success of this unit operation is so important that operators need to
understand the ramifications of their decisions or non-decisions and how they could
affect the downstream processing.
Heap leaching is an operation that can be described as a scientific art whereby principles
of science can be used to guide experienced personnel in attaining their goals. Its success
or otherwise is dependent upon a number of factors, notably:

  • The type of ore to be treated
  • The extent of testwork needed to characterise the process
  • The interpretation of the testwork results
  • Ore preparation prior to stacking
  • Agglomeration requirements

and the list goes on.
Although many of these factors or issues can be, and are, scientifically interpolated and
used, their understanding alone does not guarantee a successful heap leaching operation.
Some of the issues to be discussed that can make or break an operation could relate to:

  • Compliance with the “smaller” requirements of environmental authorities
  • Adequate and timely drainage of solution from the base of a leaching lift.
  • The degree of saturation in the pads
  • Heap porosity. Coarser or finer ore, which is better?
  • Higher or lower irrigation rates. Which would produce a better result?
  • Laying out irrigation pipe work for ease of operation and maintenance
  • The addition of water, raffinate during agglomeration where needed.

These sorts of issues are generally personnel dependent and they have the capacity to
inflict unknowing harm on the operations if they are not addressed adequately and in a
timely manner.
Finally, regardless of the scientific principles used for ore preparation, stacking and heap
leaching, the success of this part of the project depends heavily on the personnel involved.

Read the paper here