Over the years, INAP has instigated and funded a number of key acid drainage research projects to fill knowledge gaps. Cutting-edge technologies are studied, acid drainage (AD) measures at specific sites are examined, and literature reviews are undertaken to summarise AD state-of-the-art.
Current and Ongoing INAP projects are:
- Global Cover System Guidance Document and Design Tool (On Going)
This Global Cover System Guidance Document, like the GARD Guide, is intended as a best practice summary to assist mine operators, excavators, and regulators to address issues where cover systems can be employed. The Global Cover System Guidance Document will be of interest to the same groups of individuals outlined in Section 1.1 of the GARD Guide.
The Global Cover System Guidance Document is a technical document designed primarily for a scientist or engineer with a reasonable background in chemistry and the basics of engineering with little specific knowledge of cover system design that will be tasked with the closure of a Waste Site Facility (WSF). The underlying science and technology of cover system design is discussed in sufficient detail that the reader can understand the general elements of cover design, construction and monitoring, but the discussion stops short of site-specific details on geochemical kinetics and solute transport hydrodynamics. Rather, the document guides the reader through the logical framework of cover system design for WSF closure.
Accompanying the narrative is a design tool that walks users through relevant climatic factors in determining best cover system design alternative for a desired performance design criteria. This allows users to understand what a realistic objective is when determining best cover system design alternatives based on their site specific climate. Additionally, the tool refers to site-specific elements integral to the design where commentary is provided in the Guidance Document.
INAP contracted O’Kane Consultants Inc. to prepare a technical guidance document that addresses these evolving approaches, one that provides up-to-date information for designers, regulators, and other stakeholders in the design, construction, operation, and monitoring of cover systems for both reactive and non-reactive mine waste during operations and closure. It builds on regional guides and the Global Acid Rock Drainage (GARD) Guide, which was funded and is maintained by INAP. To date, cover system design guidance that addresses the influence of climate does not exist beyond specific site examples or within a regional context. Case studies that include the full breadth of climatic regions are a key component of this document’s attempt to fill that gap.
The purpose of this document is to provide guidance on the design, construction, and performance monitoring of cover systems at mine sites globally. The reader assumes full responsibility for any action taken as a result of the information contained herein.
- Diavik Test Pile Research
Prediction techniques for the behaviour of sulphide containing waste rock dumps could be significantly improved with large-scale waste rock testing. The high costs involved with such testing prompted INAP members to commission the design of a Scale-up study. The project was initiated in September, 2004. Based on this design, a project was developed at the Diavik Mine in Northern Canada. A suite of acid drainage prediction tests are being carried out to be followed by the construction of a fully instrumented test pile of waste rock. This will enable researchers to better understand what actually happens inside the waste rock pile and how this compares to various prediction methods. INAP members were invited to a site visit in August of 2008. The project continues being jointly funded by INAP, additional contributions from INAP member companies, the Mine Environment Neutral Drainage (MEND) project in Canada, and the Canadian National Science and Environment Research Council (NSERC).
- Global Acid Rock Drainage Guide (GARD Guide) (Ongoing)
The International Network for Acid Prevention is pleased that our vision of creating a ‘Global Acid Rock Drainage Guide’ is a reality. The official roll-out of the GARD Guide was on June 23, 2009 at ICARD 8 in Skelleftea, Sweden..The development of the Global Acid Rock Drainage (GARD) Guide was sponsored by INAP with the support of the Global Alliance. The GARD Guide was created through the contributions of many individuals and organizations. A team lead by Golder Associates prepared a draft of the Guide.The GARD Guide deals with the prediction, prevention and management of drainage produced from sulphide mineral oxidation, often termed “acid rock drainage” (ARD). It also addresses metal leaching caused by sulphide mineral oxidation.
The GARD Guide is intended as a state-of-the-art summary of the best practices and technology to assist mine operators and regulators to address issues related to sulphide mineral oxidation.
See the GARD Guide web page for complete project details.
- INAP Pit Lake Database
On a global scale, pit lake monitoring programs have generated a wealth of data on the geochemistry of pit lakes over the past three decades. These data could provide valuable insight on the likely water quality of future pit lakes and the design of mine closure plans. As such, there is a great need for an online, searchable database of pit lake observations. Between 2010 and 2012, INAP has funded the development of the INAP Pit Lakes Database (http://pitlakesdatabase.org) which compares the surface water chemistry (pH, electrical conductivity, major cations and anions, and trace metals) of existing pit lakes based on location, ore body type, host rock, and commodity. For a user-specified parameter, the database generates pH-versus-concentration plots for all pit lakes color-coded by ore deposit type, plus time-versus-concentration plots for individual lakes. For a given ore body type, the database calculates the minimum, maximum, and median concentrations of each parameter which can be used to estimate the likely range of future lake water quality in pit lakes developing in similar ore bodies. The database will also calculate the variance between these observed data ranges and predicted values entered by the user. The database was designed and developed by Emmon Johnson (M.Sc. Graduate Student) and Devin Castendyk (Associate Professor) at the Department of Earth and Atmospheric Sciences, State University of New York, College at Oneonta. The developers welcome contributions of water quality data from existing pit lakes. For questions about the database or to contribute data, please email Devin Castendyk at: firstname.lastname@example.org.
Completed Research Projects
- Store and Release Covers – The Role of Vegetation (Stage 2)
- ADTI-MMS Pit Lake Workbook
- Evaluation of the Long Term Performance of Dry Covers
- Waste Rock Dump Characterization
- Treatment of Sulfate in Mine Effluents
- Rum Jungle Waste Rock Cover
- Diffusive Gradients in Thin-films
- Co-Mixed Tailings Waste Rock and Slag
More information, including project reports and presentations, can be made available by contacting the Technical Manager, Gilles Tremblay.
1. Designing Effective Store – Release Covers for the Long–Term Containment of Mine Waste – The Role of Vegetation (Stage 2)
The former Australian Centre for Minerals Extension and Research (ACMER) research project, managed by the Centre for Mined Land Rehabilitation at The University of Queensland, addressed the following objectives: (1) to use water balance data for vegetated store-release covers to assess the performance of existing covers, and contribute to recommendations of future covers, (2) provide a workable model that links into existing cover water balance models, and effectively describes annual water use as a function of weather, leaf area index, changes in root zone properties and cover construction technique, and (3) facilitate significant improvement in the capacity of existing water balance models to describe hydrological processes in waste storage facilities. The work included quantifying and modeling the water uptake processes of different soil and vegetation community combinations which were (or are being) used as store-release covers at two established sites with differences in climate, vegetation, geology and soils from western and eastern regions of Australia.
In addition to the project report, a list of publications originating from research within this project is available.
2. Workbook on Pit Lake Characterization, Modeling, and Remediation Approaches
Pit lakes are complex geochemical systems that require a multidisciplinary approach to predict their post-mining water quality and to develop mitigation strategies to improve their water quality. In 2009, the Pit Lake Workbook Committee of the Acid Drainage Technology Initiative, Metal Mining Sector (ADTI-MMS) produced one of the first comprehensive guidebooks exclusively devoted to pit lakes, titled Mine Pit Lakes: Characteristics, Predictive Modeling, and Sustainability. This 304-page guidebook is a unique international collaboration addressing all aspects of pit lake characteristics, planning, predictive modeling, remediation, and sustainable development for both arid and humid climates around the world. Of the 27 contributing authors, 7 are from Australia, 5 are from Canada, and 3 are from Germany, with the remainder from the United States. Recognizing the similarities between precious-metal, base-metal, uranium, coal, iron, diamond, aggregate, and oil sands mine pit lakes, the guidebook is written for all sectors of the mining industry where open pit mining techniques are employed. The guidebook was edited by Devin Castendyk (Associate Professor, State University of New York, College at Oneonta), and Ted Eary (Principal Geochemist, InTerraLogic, Inc., Fort Collins, Colorado), and published by the Society for Mining, Metallurgy, and Exploration (SME), Littleton, Colorado. Copies may be purchased online at:
3. A study to improve our ability to accurately predict the long-term performance of dry covers.
Dry cover systems are one of the most common preventative measures used to control acid drainage. Accurately predicting the long-term performance of covers is a vital part of minimising the mining industry’s AD legacy issues. With this objective a study on the long-term stability of dry covers was commissioned to O’Kane Consultants Inc.
- Identified and defined factors that affect long-term performance.
- Evaluated state-of-the-art tools for modelling dry cover systems.
- Provided recommendations for improving and validating existing models.
→ Click here for the final report (1674 KB)
4. A characterization study of the geo-chemical and hydrological nature of 2 waste rock dumps that were being dismantled by member companies.
In 2000, waste rock dumps from the Rio Tinto Kennecott Ridgeway Mine and the Inco Whistle Mine needed to be relocated. The opportunity was seized to study the geochemical and hydrological nature of the waste rock dumps and the extent of oxidation zones within them. The project generated much interest and was jointly funded by INAP, NSERC, and R&D Start Funds. Dr. Ward Wilson from UBC, Maree and Stuart Miller from EGi, and David Williams from the University of Queensland lead the study. The findings from the work link the hydrological and geo-chemical nature of the dumps, which contain complex hydrological pathways that dictate the geo-chemistry of the released drainage. There is an indication that many of the layers within the dumps contain large amounts of stored oxidation products and soluble metals. The layers may not have an adequate degree of saturation to allow water to flow through them, thus reducing final drainage concentrations.
→ Click here for the final report (806 KB)
5. A review of sulphate treatment practices and a discussion of legislation trends “Treatment of Sulphate in Mine Effluents”.
Very little research has been undertaken on the treatment of sulphate in mine effluents. INAP members saw the need to fund a literature review of state-of-the-art sulphate treatment processes including regulations and guidelines from governments and agencies around the world. Lorax Environmental (the consultant) carried out the study, which describes methods for removing sulphate and metals from mine effluents and associated operating costs. Case studies of successful operations are also documented.
→ Click here for the final report (3416 KB).
6. A case study on the deteriorating performance of the 18 year-old Rum Jungle dry cover system in Northern Territory, Australia.
The 18 year old cover Rum Jungle in Northern Territory, Australia is one of the oldest cover systems for which the design, construction, and continuous monitoring date are well documented. Water infiltration through the covers increased significantly in the last few years and this project was designed to use the data history to understand the reasons for the deterioration performance. The Australian Nuclear Science and Technology Organisation (ANSTO) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) were contracted to undertake the work. The study found that the cover materials no longer met the original design specifications –particularly for permeability which increased by several orders of magnitude. Findings from the study indicated that the increased permeability may be attributed to:
- A shortage of cover material during construction resulting in bare patches;
- A combination of biological and physical process – galleries formed by termites and ants, root growth from
- the pasture grasses and the few volunteer trees, and an extensive system of shrinkage/dessication cracks.
→ Click here for the final report (2224 KB)
7. A study to use Diffusive Gradient in Thin-films (DGT) technology (or gel samplers), which allows for in situ determinations of free-ion activity of metals in mine water and provides a more accurate representation of biological impacts than measurements of total or dissolved metal concentrations.
Conventional water quality analysis is restricted to measuring total and dissolved metals in discrete water samples. Lorax (the consultant) was commissioned to undertake a study on the use of diffusive gradients in thin-films (DGT) – or gel samplers as this technology can provide a more accurate estimation of metal toxicity in water.
The project findings indicated that the use of DGT provides a measure of metal bioavilability, and hence a more representative measure of metal toxicity in water. This is mainly due to the fact that DGT detect free or weakly complexed metal species without measuring constituents that are not bio-available. The use of DGT also has the advantage of being an in-situ measure and can provide a time-integrated estimation over a deployment interval. This is especially beneficial when dealing with highly variable water quality, as is usually the case when measuring mining effluents discharged into natural watercourses. The use of DGT is, however, limited to a certain pH range (5-9 for most metals, 2-11 for Cu) and is not effective in waters of very low cation concentration. The study concluded that the DGT technique can be applied to various aspects of environmental chemistry, however more work is required to validate the use of DGT in mining-impacted waters.
→ Click here for the final report (1587 KB)
8. A review of the potential use of co-disposed waste rock and tailings for the construction of covers on mine waste dumps as a practical, low cost AD prevention method.
Following a literature review on the application of co-disposed tailings and waste rock to construct covers, this project was designed to examine the stability and hydraulic conductivity of a number of co-mixtures with varying ratios of tailings, waste rock and slag. Klohn Crippen in association with Dr. Wilson from the University of British Columbia, were commissioned to undertake the study.
The findings of the work can be summarized briefly as follows:
- Well-graded materials provide the best performance for the construction of soil cover systems with high resistance to erosion, frost, and desiccation. The co-mixtures of slag, waste rock and tailings provided a material that showed both excellent geotechnical characteristics and varying degrees of hydraulic conductivity.
- In-situ mixing of tailings and waste rock is feasible for semi-competent rock types and has low costs. However, this method provides poor cover performance on dump slopes. Layering tailings and waste rock results in good covers and involves low costs, but is also difficult to apply on slopes. Mechanically placing engineered mixtures of tailings and rock provides the most flexible cover option for flat and sloping surfaces. Waste rock would optimally be crushed to 50-75 mm minus size to have the right grading, however this method involves double the cost of the other methods.
- When bentonite was added to the co-mix the conductivity decreased, indicating that once the characteristics had been determined it would be possible to blend mixes with varying properties to meet the needs of the cover being designed.
- Estimates of cost indicated that the covers would be potentially expensive and future focus would have to include an examination of means to provide these mixes in a cost effective manner. Bentonite addition particularly added considerable costs to the overall cost per area of co-mix covers.
→ Click here for the final report (202 KB)