Completed Research Projects

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1. 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.
   
   The study:
   • 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).

2. 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).
   
   
3. 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).
   
   
4. 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).
   

5. 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).
   
   
6. 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).