Identification and Management of Dispersive Mine Spoils
Validation of a Risk Assessment Model for Tunnel Erosion on Waste Rock Dumps
Identification and Management of Dispersive Mine Spoils
Background
Dispersive spoils are an important cause of waste dump instability, due to large-scale piping failures, extreme unsuitability for revegetation, or relatively localised piping failures of constructed drainage systems. Waste dumps constructed of dispersive spoils are typically unstable for very long periods (often for the life of the dump), representing a significant ongoing cost for repair that is typically ineffective.
Dispersive materials occur in a number of mining areas, with well-known examples including the dispersive Tertiary spoil common through the central Queensland coal fields, and highly sodic paleochannel clays through the West Australian goldfields.
Despite a plethora of research on measurement of dispersion, attempts to relate dispersion measurements to erosion potential are relatively few, typically dealing with erosion processes of limited field relevance. None have considered potential for tunnel erosion, and current tests of dispersion have poor ability to predict erodibility.Objectives
Develop, for mine sites with dispersible soils and spoils, procedures to improve the identification and management of these materials.
Outcomes
- Procedures for identification of dispersive spoils which can preferably be applied to drill core samples;
- Methods for prediction of potential erosion risks for various degrees of dispersion;
- Recommendations for placement of dispersive materials so that waste dump stability is not compromised; and
- Recommendations for management of existing dumps of dispersive material.
Methodology
- Evaluate erosion mechanisms on dispersive materials, to obtain a realistic measure of erodibility of a range of materials of varying properties and dispersion, and to develop methods of assessing erosion risk;
- Evaluate methods for measuring dispersion, and the identification and/or development of a method that correlates strongly with field and laboratory measured erodibility and erosion risk;
- Investigate methods for dealing with dispersive materials, including design/construction of new waste rock dumps, and stabilising existing dumps; and
- Determine the microstructural, mineralogical and physico-chemical properties of dispersive materials.
Project Team
- Dr Rob Loch (Landloch Pty Ltd) (Project Leader)
- Dr Steve Raine (University of Southern Queensland)
- Prof Bob Gilkes (University of Western Australia)
- Assoc Prof David Williams (University of Queensland)
Project Duration
2002 - 2004
Project Sponsors
- Australian Premium Coals Pty Ltd
- Newcrest Mining Limited
- Newmont Australia Limited
- St Ives Gold Mine Co Pty Ltd
- Resolute Mining Limited
Project Report
More Information
Risk Management Strategies for the Surrender of Open-Cut Coal Mine Spoil Areas in the Bowen Basin Coalfields
The economic component of this project was undertaken by a University of Queensland postgraduate student, Assoc Prof Barry Golding, who was supported by a postgraduate scholarship made available by ACMER through the Queensland Coal Mine Rehabilitation Fund. This component addressed the cost-effectiveness of rehabilitated mined land in the Bowen Basin.
The project, supported by ACARP and directed by Assoc Prof David Williams, Centre for Mined Land Rehabilitation, University of Queensland and Mr Mike Gowan of Golder Associates Pty Ltd, addressed the need for a systematic process for selecting and supporting the most environmentally and economically effective strategies for the rehabilitation and future land uses of open-cut coal mine spoil areas in the Bowen Basin.The final report for this project is available from ACARP (C8039).
Validation of a Risk Assessment Model for Tunnel Erosion on Waste Rock Dumps
Background
Dispersive spoils are an important cause of waste dump instability, due to large-scale piping failures, extreme unsuitability for revegetation, or relatively localised piping features of constructed drainage systems. Waste dumps constructed of dispersive spoils are typically unstable for very long periods (often for the life of the dump), representing a significant ongoing cost for repair that is typically ineffective.
Dispersive materials occur in a number of mining areas, with well-known examples including the dispersive Tertiary spoil common through the central Queensland coal fields, and highly sodic paleochannel clays through the West Australian goldfields.
An ACMER project entitled "Identification and Management of Dispersive Mine Spoils" completed in 2004 developed improved procedures for identification of overburden that is prone to tunnel erosion and provided recommendations for management of such materials. A logical extension of that project is to develop and validate a risk assessment model for tunnel erosion on waste dumps.Objective
- Develop and validate a risk assessment model for tunnel erosion and waste dumps.
Outcome
- A practical risk assessment model that can be used to assess risks associated with various spoil types and landform design options.
Methodology
- Develop preliminary risk assessment model based upon results of Stage 1 project
- Sampling of approximately 15-20 additional tunnel-eroded sites and a similar number of "stable" sites
- Characterisation using the protocols developed in the Stage 1 project
- Validate risk assessment model using wide range of data from 30-40 sites
Project Team
- Dr Rob Loch (Landloch Pty Ltd) Project Leader
- Mr Cameron Vacher (Landloch Pty Ltd)
Project Duration
October 2005 - June 2006
Project Sponsors
Barrick Gold of Australia Limited
Macarthur Coal (C&M Management) Pty Ltd
Newcrest Mining Limited
St. Ives Gold Mining Company Pty LtdMore Information
