Predicting the behaviour of smaller mining units from larger block estimates

Snowden is presenting its newest professional development course, Change-of-Support – getting to the high grade, at its UK office in Weybridge on September 12-13.

Change-of-support is a group of geostatistical tools that allows the user to predict the behaviour of smaller mining units from larger block estimates. This process is required if the available data does not have the spatial resolution to directly estimate into mining blocks. If this issue is ignored, the resource estimate could be fatally flawed. It is therefore important for all resource geologists to understand when the application of change-of-support is required and how to select and apply the appropriate method.

This course details the theoretical background and provides practical examples, as well as software, for change-of-support tools and methods for estimation of future high grade resources. Participants will learn about:

  • The three key statistics you need to understand all geostatistics
  • How to decluster your data to estimate the underlying true grade of a deposit using a freely available declustering programme
  • In an Excel spreadsheet, the simple explanation of dispersion variance and how it applies to change-of-support
  • The background to why semivariograms describe estimation errors inherent in using your data and how (in a simple spreadsheet) dispersion variance is estimated from the semivariogram
  • How to estimate correction factors for change-of-support between point data and resource panels using your data, semivariograms and freely available software
  • The basis of the three main methods (Affine, Lognormal, Hermite) of global change-of-support with the basis of each explained in Excel
  • How to use the course software to carry out global change-of-support and compute grade-tonnage curves of future recoverable resources for a range of cutoff grades
  • The simple basis of local change-of-support methods in an Excel spreadsheet and the balance of variability between point, panels and selective mining units
  • How kriging quantifies grade smoothing and the intuitive meanings of regression slope and kriging efficiency
  • How to model the information-effect of future data
  • The background to Uniform Conditioning (UC) and Indicator Kriging (IK) as tools for constructing recoverable resource estimates
  • Example application of these methods to model validation and mine scheduling.

This two-day course includes:

  • Review of key statistics and geostatistical concepts
  • Global change-of-support methods (Affine, Lognormal, Hermite)
  • Local change-of-support methods (UC and IK)
  • Specialist software developed by Snowden for implementation of Hermite global change-of-support and UC
  • Detailed documentation and explanations of key concepts

Each aspect of the course is presented in a modular manner involving explanation, demonstration, and active experimentation. This course has been designed for resource modelling geologists and mining engineers interested in recoverable resource estimation. The content assumes a good working knowledge of resource estimation and some familiarity with advanced geostatistical concepts.

Presenter: Mark Murphy, Group Geostatistician, BAppSc (Hons) Geology, Grad.Dip.Education, MSc Mathematics and Planning, Member AIG(RP Geo). Murphy has more than 18 years experience in the mining industry working in senior exploration and mining roles. He has specific expertise in grade control (both open pit and underground), geostatistical resource estimation, risk-based resource classification, sampling, beneficiation studies and GIS applications.

All Snowden’s courses are available as on-site/in-house training.

Contact Diana Titren, Training Coordinator
[email protected]