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Reconciliation – Harder than it looks!

Author: Mike O’Brien, Technical Director, Geology & Resources, P.Geo., Pr.Sci.Nat.

Reconciliation – Harder than it looks! – Presentation delivered at the CIM Convention 2018

Reconciliation involves the collection of tonnage, grade (quality) and contained metal (product) data from disparate and hopefully independent sources. These data may be compared by means of ratios, to relate short term (ore control) model to ore reserves depleted and to relate material received at mill (measured by the mill) to material delivered to the mill. (Paraphrasing H. Parker, 2012)


“The word ‘reconciliation’ can mean very different things to different people in the mineral industry. The views of an exploration geologist compared with the views of a process engineer, will be very different. The views off a mining economist will be very different from either of the previous persons. The processes constituting the mining value chain are an unholy amalgam of engineering, chemistry and geoscience. The philosophies of the disciplines contributing to mineral extraction are distinct and frequently not aligned. Little wonder that there are frequent disagreements on how to measure the effectiveness of the overall mineral exploitation process.

In addition to discipline-specific bias, there is psychology. The attitude of people participating in a reconciliation exercise is greatly influenced by their relative positions in the organization and vested interests. ‘Blame games’ are a frequent result as different people attempt to deflect any potential criticism, even if it means pointing a finger at some other hapless member of the team. The phrase ‘the search for the guilty and the punishment of the innocent’ is a cynical but real outcome of a situation where senior management demand ‘no surprises’ while the nature of most deposits results almost inevitably in some form of unpleasant surprise, the more data becomes available.

So how can the ‘surprises’ be minimized and reconciliation become a tool for process improvement rather than a blunt instrument to push the innocent and obscure the facts? An holistic approach must be harnessed to involve the key disciplines in an honest and fruitful dialogue to measure and improve the jobs that need to be done. Senior management need to commit to such a process and create secure environment where honesty trumps the search for scapegoats.

This is easier said than done, but from an early stage, break the silos of geoscience, mineral processing and mining engineering and create dialogue.” (Synopsis of the presentation on, rtrvd. 2018-09-30)

This presentation deals with:

  • What is Reconciliation?
  • Uses of reconciliation
  • Approach to reconciliation
  • Examples of reconciliation problems and solutions

Download the pdf of the presentation here.

About Mike O’Brien

Technical Director, Geology & Resources, P.Geo., Pr.Sci.Nat. Ausenco, Vancouver, Canada

For three decades Mike has been making a difference to Mineral Resources and mines. On the technical front, he has extensive experience in Mineral Resource estimation and geological modelling. He has managed technical teams to achieve results in mining companies and in consultancies. While the majority of his experience has been in gold deposits, he has expertise in the uranium, base metals and multi-product environment. A qualified geologist and geostatistician, he has been a team member and reviewer of due diligence and feasibility exercises in South Africa, Brazil, Ghana, Namibia, DRC, Russia, Kazakhstan, Uzbekistan, Colombia, Peru and the United States. Specialties: Mineral Resource estimation, geostatistics, Mineral Resource classification, Mineral Resource reporting codes, SAMREC, JORC.


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