www.rpacan.com www.rpacan.com Rock Solid Resources. Proven Advice. Rock Solid Resources. Proven Advice. www.rpacan.com Rock Solid Resources. Proven Advice. Overview of the 2019 Mineral Resource and Mineral Reserve Best Practices Guidelines CIM MES Group, January 29 2020 Reno Pressacco, P.Geo., Principal Geologist, RPA Inc. Toronto Denver London Vancouver Quebec City
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Overview of the 2019 Mineral Resource and Mineral …...5.5 Estimation Domains New 6.0 MINERAL RESOURCE ESTIMATION 6.1 Introduction Retained 6.2 Exploratory Data Analysis Retained
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• Peer review: 69 individuals were solicited for comments, 23 responses received. The group comprised respondents to the public Call for Volunteers (September & October 2018), and others who expressed interest in participating.
• Public Comment: Approximately 1,500 visits were made to the web page. A total of 40 responses received.
• Regulator Review and Comments: Canadian Securities Administrators (CSA) / Autoritès canadiennes en valeurs mobilières.
• The result is a document that is written by users, for users.
The majority of the responses were supportive of the proposed language.
Some were not ……….. .
In general, the responses suggested/requested additional guidance on specific topics.Source: http://www.easyblindsonline.co.uk/blog/wp-content/uploads/2014/10/darth-vader.jpg
• Historically, the RPEEE test has been achieved at the interpretation stage where the mineralized intervals were selected using strict criteria of “economic grades over mineable widths”.
• These criteria are being applied with less rigor in modern Mineral Resource estimates, leading to potentially misleading statements……… .
• Reminder that Qualified Persons are responsible for their opinions and statements, with the full understanding that they are subject to an enforceable code of ethics judged by your peers.
• Mineral Resource statements prepared using no minimum widths are often misunderstood, as the target audience has an expectation of “Reasonable Prospect for Eventual Economic Extraction.”
• For example, is a tonnage and grade statement such as provided above an accurate estimate of the potential tonnages and grades that can be reasonably excavated?
• “We’re modelling the geology” or “We report the in-situ tonnes and grades.” This often then leads to:
• “Yes, but if we have so many Mineral Resources, why don’t we have any Mineral Reserves?”
• It’s not just about geology. “Mining is the process of turning rock into money.”
• Practitioners are reminded that there is an expectation that Mineral Resources have considered and represented the practical limitations of mining (the “Reasonable Prospects” test).
• Open pit Mineral Resources are reported with a cut-off grade (or value), and a constraining surface.
• The use of these criteria demonstrate the technical and economic requirements of the “Reasonable Prospects” test for the declaration of a Mineral Resource (for an open pit scenario).
• The application of a constraining surface DOES NOT represent an attempt to estimate Mineral Reserves.
• Before computers, Mineral Resources were estimated by use of longitudinal projections or cross-sectional interpretations. Many “discussions” took place….
• In many cases the mineralization occurs in such a manner such that some of the non-mineralized material (waste) must be excavated along with the mineralization.
• Because the tabulation of the Mineral Resources were historically done by hand, the inclusion or exclusion of desired or undesired blocks was easily done.
• Mineral Resource statements for underground mining scenarios must satisfy the “reasonable prospects for eventual economic extraction” by demonstration of the spatial continuity of the mineralization within a potentially mineable shape.
• In cases where this potentially mineable volume contains smaller zones of mineralization with grades or values below the stated cut-off (sometimes referred to as “must take” material), this material must be included in the Mineral Resource estimate.
• At a minimum, these constraints can be addressed by creation of constraining volumes.
• Constraining volumes should be used in conjunction with other criteria for the preparation of Mineral Resource estimates.
• In many cases where the Mineral Resource estimate is prepared by digital methods, isolated and discontinuous blocks may be present that have grades or values above the stated cut-off grade or value.
• For underground mining methods, these blocks should be excluded from the Mineral Resource statement if their spatial continuity or their size is insufficient to achieve a potentially mineable shape above the nominated cut-off grade or value.
• We continue to learn some very hard lessons. The experiences are painful and expensive.
• Many of the shortcomings of modern MRMR statements are a result of poor practical judgement and/or a poor understanding of how the software programs function.
• “Although computers are fast and provide much more data, they are not a substitute for judgement.” (Clow, 1990)
• No amount of new technologies, elegant formulae or computational power can replace a practical understanding of the mineralization style under consideration and knowledge of appropriate mining and processing methods.
• The purpose of these Guidelines is to capture the lessons from our past experiences as well as propose solutions to the current challenges that
we face. “Only a fool learns by their own mistakes. The wise man learns from the mistakes of others.” (Otto von Bismark, 1815-
1898)
• The Guidelines are written by Practitioners who have learned these
lessons. “We stand on the shoulders of giants.” (Isaac Newton, 1675)