Mine Geology and Geophysics for Mining Operations

Introduction

Mine geology and geophysics sit at the point where subsurface interpretation becomes an operational decision. Every tone scheduled, every dig line marked and every blast designed rests on a geological model that was built from imperfect data. Where that model is wrong, the cost is paid downstream in dilution, ore loss, misdirected material, unplanned ground failure and plant underperformance. This five-day course covers the full working chain from geological observation through drilling, sampling, geophysical survey and resource estimation, to grade control and reconciliation at the mine face. It gives equal weight to the two disciplines: geology as the framework of interpretation, and geophysics as the principal means of seeing beyond the drill hole. The emphasis throughout is operational — participants work with the data types, quality problems, decisions and trade-offs that arise on a producing mine, not with idealized examples. The programme is method-neutral and code-neutral. Reporting codes, software platforms and survey technologies are covered so that participants can judge which is appropriate to a given problem, rather than to promote any single system.

Objectives

By the end of this course, participants will be able to:

• Interpret geological maps, sections and drill logs and explain how each contributes to a three-dimensional geological model
• Describe the principal ore deposit types and relate deposit geometry to mining method and grade control strategy
• Select appropriate drilling and sampling methods for a stated objective and identify the errors each introduces
• Design, run and interrogate a QA/QC programme, and determine whether an assay batch is fit to be used
• Match a geophysical method to a target on the basis of physical property contrast, depth and required resolution
• Explain the principles of geophysical data processing and inversion, and recognise the limits of what an inverted model can prove
• Apply basic geostatistical concepts to assess grade continuity and estimation confidence
• Explain Mineral Resource and Ore Reserve classification and the responsibilities attaching to the Competent or Qualified Person
• Conduct a reconciliation analysis and diagnose whether variance originates in sampling, modelling or execution
• Identify geological and geophysical inputs to ground control, dewatering, void detection and environmental management

Training Methodology

The course is delivered as a mix of structured instruction and applied work, with roughly half of the contact time given to exercises, worked datasets and discussion. Methods used include:

• Instructor-led sessions supported by field photographs, sections and real survey products
• Hands-on exercises using supplied drill hole, assay, QA/QC, geophysical and reconciliation datasets
• Core logging and hand specimen identification exercises where materials are available at the venue
• Case study analysis drawn from published operational examples
• Small-group problem solving with structured feedback
• Facilitated discussion of participants' own operational issues, where these can be shared
• An end-of-course integrated case study combining geology, geophysics and grade control

Participants are encouraged to bring anonymised data or problems from their own operations. Where confidentiality permits, these can be substituted for supplied datasets in the workshop sessions.

Who Should Attend?

This course is designed for technical and supervisory personnel whose work depends on, or contributes to, the geological model of an operating or developing mine:

• Mine geologists, grade control geologists and exploration geologists
• Geophysicists and geophysical technicians supporting mining operations
• Mining engineers, mine planners and drill and blast engineers
• Geotechnical and hydrogeological engineers
• Resource and reserve estimation practitioners
• Metallurgists and processing engineers seeking to understand feed variability at source
• Survey, database and technical services personnel
• Technical managers and superintendents responsible for geology or technical services functions

Course Outline

The programme runs over five days. Each day is built around four sessions, with workshop or exercise work embedded in the final session.

Session 1 — The Mine Geologist in the Mining Value Chain

• Roles and accountabilities of the geology function from exploration through to closure
• Interfaces with mine planning, drill and blast, survey, geotechnical, processing and metallurgy
• The cost of geological uncertainty: how model error propagates into schedule, dilution and plant recovery
• Data ownership, version control and the single source of truth

Session 2 — Geological Fundamentals Refresher

• Rock-forming minerals and the identification of ore and gangue minerals in hand specimen
• Igneous, sedimentary and metamorphic rock classification relevant to mine settings
• Alteration assemblages and their use as vectors towards mineralisation
• Weathering profiles, regolith and the oxide–transition–fresh boundary

Session 3 — Structural Geology for Mining

• Folds, faults, joints, shear zones and their control on ore geometry
• Measuring and recording structural data: strike, dip, dip direction, plunge, lineation
• Stereonet interpretation and structural domaining
• Structural controls on both grade continuity and ground stability

Session 4 — Ore Deposit Models

• Classification of the principal deposit types: porphyry, epithermal, VMS, orogenic gold, sediment-hosted base metals, laterite, evaporite and industrial minerals
• Deposit geometry, zonation and its implications for mining method selection
• Using the deposit model to set exploration and grade control strategy
• Workshop: build a first-pass geological model from a supplied map and section set

Session 1 — Drilling Methods and Their Limitations

• Reverse circulation, diamond core, rotary air blast, auger and sonic drilling: selection criteria
• Sample recovery, contamination and down-hole smearing, and their effect on reported grade
• Collar surveying and down-hole survey tools; the consequences of undetected hole deviation
• Drill programme design: spacing, orientation and the drilling–confidence relationship

Session 2 — Logging Standards and Discipline

• Lithological, alteration, mineralisation and structural logging conventions
• Alpha, beta and gamma angle measurement on oriented core
• Geotechnical logging: RQD, fracture frequency, joint condition
• Building and enforcing a logging codes dictionary to keep data machine-readable

Session 3 — Sampling Theory and Practice

• Gy's sampling theory in practical terms: fundamental sampling error, sample support, correct sample delimitation and extraction
• Nugget effect and its consequences for sample mass and assay variance
• Sample preparation flowsheets: crushing, splitting, pulverising and the errors introduced at each stage
• Assay method selection: fire assay, aqua regia, four-acid digest, XRF, and where each is fit for purpose

Session 4 — QA/QC and Database Integrity

• Certified reference materials, blanks, field duplicates, coarse duplicates and pulp duplicates: insertion rates and placement
• Constructing and reading control charts; setting failure criteria and batch rejection rules
• Umpire laboratory check programmes and bias detection
• Database validation rules, audit trails and the handling of legacy and third-party data
• Workshop: interpret a QA/QC dataset and decide whether the batch is acceptable

Session 1 — Physical Properties: The Link Between Geology and Geophysics

• Density, magnetic susceptibility and remanence, electrical resistivity and conductivity, chargeability, seismic velocity, and natural radioactivity
• Why a target must contrast with its host rock to be detectable
• Petrophysical measurement programmes on core and their role in constraining interpretation
• Matching the physical property contrast to the survey method

Session 2 — Potential Field and Radiometric Methods

• Magnetic surveys: ground, airborne and drone platforms; data reduction and reduction to the pole
• Gravity and gravity gradiometry: applications to density contrasts, voids and massive sulphides
• Radiometrics for lithological mapping and uranium and rare earth targeting
• Interpretation products: derivatives, analytic signal, tilt derivative and depth estimation

Session 3 — Electrical, Electromagnetic and Seismic Methods

• Resistivity and induced polarisation for disseminated sulphides and alteration mapping
• Time-domain and frequency-domain electromagnetics: ground, airborne and down-hole EM
• Down-hole EM as a step-out targeting tool from existing drill holes
• Seismic reflection and refraction in hard rock and coal settings; limitations and cost drivers
• Borehole geophysical logging: gamma, density, sonic, calliper, resistivity and televiewer

Session 4 — Survey Design, Inversion and Integration

• Resolution, depth of investigation, line spacing and signal-to-noise trade-offs
• Processing workflow from raw data to gridded product
• Inversion fundamentals and the problem of non-uniqueness: why several models can fit one dataset
• Geologically constrained and joint inversion; integrating geophysics with drilling and mapping
• Workshop: select and justify a geophysical programme for a stated exploration or operational target

Session 1 — Grade Control in Open Pit and Underground Operations

• The grade control cycle: sampling, modelling, mark-up, execution and verification
• Blast hole sampling practice and its known biases; face and chip sampling underground
• Ore and waste delineation, dig line design and the practical limits of selectivity
• Quantifying and managing dilution and ore loss
• Sensor-based tools at the face and on the belt: portable XRF, PGNAA, on-line analysers and ore sorting

Session 2 — Introduction to Geostatistics

• Descriptive statistics, distribution shape and the treatment of extreme grades
• The variogram: range, sill, nugget and anisotropy, and what each tells you about continuity
• Estimation methods: inverse distance, ordinary kriging and indicator approaches
• Conditional simulation and its use in quantifying grade risk

Session 3 — Block Modelling and Resource Classification

• Domaining and the enforcement of hard and soft boundaries
• Block size selection and the information effect
• Density assignment and bulk density measurement methods
• Mineral Resource and Ore Reserve reporting under the CRIRSCO family of codes, including JORC, NI 43-101 and SAMREC; the role and obligations of the Competent or Qualified Person
• Modifying factors and the Resource-to-Reserve conversion

Session 4 — Reconciliation and Continuous Improvement

• Reconciliation factors between resource model, grade control model, mine production and plant feed
• The mine call factor and the diagnosis of persistent bias
• Root cause analysis: distinguishing sampling error, model error and operational execution error
• Workshop: analyse a reconciliation dataset and identify the dominant source of variance

Session 1 — Rock Mass Characterisation and Ground Control

• Rock mass classification systems: RQD, RMR, Q and GSI
• Laboratory and field testing of intrinsic rock properties
• Structural data in slope design: kinematic analysis of planar, wedge and toppling failure
• Underground ground support selection and the geologist's contribution to ground control management plans
• Monitoring technologies: slope stability radar, prisms, extensometers, InSAR and microseismic systems

Session 2 — Hydrogeology and Void Detection

• Aquifer types, hydraulic conductivity and the sources of groundwater inflow to pits and workings
• Dewatering strategy and the geological controls on its effectiveness
• Geophysical detection of water-bearing structures, karst features, old workings and voids
• Inrush risk assessment and the geologist's role in the permit and controls process

Session 3 — Environmental and Closure Applications

• Acid rock drainage and metal leaching: geological prediction, static and kinetic testing
• Waste rock and tailings characterisation and geochemical block modelling
• Geophysical monitoring of tailings storage facilities, seepage and containment integrity
• Geological inputs to closure planning and post-closure land use

Session 4 — Digital Integration and Course Consolidation

• The integrated 3D data environment: implicit modelling, block models and the role of common mine geology software platforms
• Automated logging, hyperspectral core scanning and machine-assisted interpretation: current capability and current limitations
• Communicating geological uncertainty to non-geologists in operations and management
• Course case study: an integrated geology-geophysics-grade control problem worked in teams
• Individual action planning and workplace application commitments