Guidelines For Metal Leaching and Acid Rock Drainage at Minesites in British Columbia. William A. Price and John C. Errington. Ministry of Energy and Mines. August 1. 99. 8ACKNOWLEDGMENTS1.
INTRODUCTION1. 1 Purpose of Guidelines 1. Metal Leaching and Acid Rock Drainage 1. Development of Guidelines 2. GUIDING PRINCIPLES 3. PREDICTION3. 1 Prediction Principles 3. Phased Approach 3. Avoiding Errors 3.
Acid rock drainage prediction manual by Coastech Research Inc., 1991,Canada Centre for Mineral and Energy Technology = Centre canadien de la technologie des minéraux.
- Introduction. Acid Rock Drainage (ARD) Prediction provides an introductory course and application reference for students, technicians, and practicing geochemists.
- Acid Rock Drainage Prediction Manual iii DISCLAIMER The user of this report should assume full responsibility for any action taken as a result of the.
- Acid Rock Drainage Prediction Manual March 1991 Effective Date: 01 March 2014 Original Date of Accreditation: 01 March 1999 Based on MEND Acid Rock.
Prediction Manual 3. Step 1 - Identify and Characterize Geological Materials 3. Step 2 - Predict the Metal Leaching and ARD Potential 3. Test Procedures 3.
Step 3 - Develop Mitigation and Monitoring Programs 4. MEASURES TO PREVENT OR REDUCE METAL LEACHING AND ARD 4. Mitigation Principles 4. Prevention and Reduction of ML/ARD 4. Available Mitigation Strategies 4. Effectiveness of Different Mitigation Strategies 4. Selection of the Best Mitigation Strategy 4.
CANMET Mining and Mineral Sciences Laboratories Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials Report prepared by. Waste rock materials from mining, mineral processing and related operations, which contain sulphide minerals such as pyrite, have the potential to be the source of.
Contingency Planning 4. Information Requirements. UNDERWATER STORAGE5. General Considerations.
Information and Design Requirements 5. Constructed Surface Impoundments 5. Flooded Pits and Underground Workings 5.
Underground Bulkheads 5. Natural Water Bodies.
BLENDING OF PAG AND NPAG WASTES6. General Considerations 6. Neutralization Mechanisms 6.
Problems With Demonstrating Effectiveness 6. Information and Design Requirements 7. COVERS7. 1 General Considerations 7. Information and Design Requirements 8. DRAINAGE COLLECTION AND TREATMENT8. General Considerations 8.
Information and Design Requirements 8. Long- term Active Chemical Treatment 8.
Commercial Acid Leaching 8. Passive Drainage Treatment 9. MITIGATION OF SPECIFIC MINE COMPONENTS9. Modifications to Tailings.
Modifications to Open Pits and Underground Workings. Construction Materials. GEOTECHNICAL AND HYDROLOGICAL CONSIDERATIONS1. General Requirements 1. Drainage Management 1. Geotechnical Requirements 1. Discharge and Receiving Environment Objectives 1.
BRITISH COLUMBIA MINE REGULATION1. Permitting and Mine Approval. Financial Security 1.
Operational Monitoring 1. Annual Reclamation Reports 1. ML/ARD Prediction and Prevention Plans 1. Historic Minesites with Metal Leaching and ARD Concerns 1. Exploration 1. 2.
COMMITMENT TO IMPROVED PRACTICES AND REGULATION1. Research REFERENCESFOOTNOTESThese guidelines have been created with assistance from members of the Ministry of Energy and Mines’ Metal Leaching/Acid Rock Drainage Expert Advisory Committee: Garry Alexander - - Ministry of Environment, Lands and Parks Stephen Day - - Norecol, Dames and Moore Keith Ferguson - - Placer Dome North America Ltd. Glenda Ferris - - Northern Ecology Action Committee Walter Kuit - - Cominco Ltd. Kevin Morin - - Minesite Drainage Assessment Group Alan Young - - Environmental Mining Council At the request of the authors detailed reviews were also carried out by: Peri Mehling - - Mehling Environmental Management Gilles Tremblay - - MEND Secratariat The authors gratefully acknowledge the extensive technical contributions and the time devoted to this project by the above individuals. However, their support should not be construed as an endorsement, in whole or in part, by them or by the organizations they represent. Kim Bellefontaine, Ministry of Energy and Mines, is thanked for the extensive improvements she made to the clarity and to geological aspects of the document. Tim Eaton, Ministry of Energy and Mines, checked geotechnical aspects of the report.
Bob Hart and Jim Hofwebber provided much of the detail regarding discharge and receiving environment objectives and the requirements of the Ministry of Environment, Lands and Parks. Valuable contributions were also made by Grace Harris, Carol Howell and Sylvia Van Zalingen of the Ministry of Energy and Mines; Laura Duncan of the Environmental Mining Council; and various regional reviewers of the Ministry of Environment, Lands and Parks. The Ministry of Energy and Mines is committed to improving existing practices and regulation.
Comments on this document and other aspects of metal leaching and acid rock drainage regulation should be submitted to: William Price. Mines Branch. Ministry of Energy and Mines.
Bag 5. 00. 0Smithers, BC V0. J 2. N0. Return to Table of Contents There are numerous examples throughout the world where elevated concentrations of metals in mine drainage have adverse effects on aquatic resources and prevent the reclamation of mined land. Metal leaching (ML) problems can occur over the entire range of p. H conditions, but are most commonly associated with acid rock drainage (ARD). Once initiated, metal leaching may persist for hundreds of years (Arnesen and Iversen, 1. In North America, ML and ARD (ML/ARD) have led to significant ecological damage, contaminated rivers, loss of aquatic life and multimillion- dollar cleanup costs for industry and government.
The ARD liability associated with existing Canadian tailings and waste rock is estimated to be between $2 billion and $5 billion (Feasby and Tremblay, 1. Preventing impacts from ML/ARD is the most costly and time consuming environmental issue facing the British Columbia mining industry. It is also one of the most technically challenging. Due to poor historical practices, large remediation costs, technical uncertainty and the potential for negative environmental impacts, ML/ARD is a major issue of public and regulatory concern.
Under existing British Columbia legislation and policies, mining companies are fully responsible for environmental protection and reclamation at their minesites and must demonstrate the effectiveness of their plans in the development, operation and closure phases of the mine (BCMEM and BCMELP, 1. The responsibility of regulatory agencies is to indicate, as clearly as possible, what constitutes acceptable mine design and adequate technical evidence. Although every rock, waste and minesite is somewhat unique, there are ML/ARD information needs, test procedures, design objectives and management requirements that apply under most circumstances. The primary objectives of this document and the complementary prediction manual (Price, 1. This information will assist mines in developing comprehensive proposals that include the necessary documentation and consideration of risk for sound environmental management.
The guidelines have also been produced to assist regulators and members of the public who are interested in reviewing ML/ARD work. The Ministry of Energy and Mines (MEM) endeavors to be transparent in its regulation and to carry out comprehensive, well informed mine reviews. By documenting the technical basis for present practices, MEM hopes to promote greater understanding of ML/ARD issues and to enable the identification of gaps in the knowledge base. The guidelines provide general direction on ML/ARD issues and management without limiting options and approaches. They were developed from previous experience, primarily in British Columbia, and do not apply to all minesites and conditions. Users of the guidelines, both in this Province and in other biogeoclimatic regimes or regulatory jurisdictions, must consider site- specific conditions and materials when deciding which principles and procedures apply, and how they should be implemented. The environmental impact of ML/ARD will depend on their magnitude, the sensitivity of the receiving environment and the degree of neutralization, dilution and/or attenuation.
Factors which enhance metal leaching include rapidly weathering metal- containing minerals, drainage conditions that increase solubility and high flow rates through contaminated materials. Acid generation occurs when minerals containing sulphide and elemental sulphur are exposed to the weathering effects of oxygen and water.
Acidity is generated from the oxidation of sulphur and the precipitation of ferric iron. ARD occurs when the resulting acidity is entrained by water. Although ARD has received most of the attention, the primary source of toxicity are metals. Elevated metal leaching is associated with acidic drainage due to high metal solubility and sulphide weathering rates under acidic conditions. For many rock types/environmental conditions, metal leaching will only be significant if drainage p. H drops below 5. 5 or 6.
However, neutral p. H drainage does not necessarily prevent metal leaching from occurring in sufficient quantities to cause negative impacts. While the solubility of aluminum, iron and copper is greatly reduced in neutral p. H drainage, elements such as antimony, arsenic, cadmium, molybdenum, selenium and zinc remain relatively soluble and can occur in significantly high concentrations. Unlike ARD, neutral p.
H metal leaching is generally only a concern if discharge is into a sensitive resource and/or with little dilution. High concentrations of metals in neutral p. H drainage often result from localized relatively small zones of acidic weathering. The characteristic low p. H values and rust- coloured iron staining associated with ARD are often found in natural watercourses in the vicinity of undisturbed, naturally weathered outcrops of sulphide- bearing rock (i.
The Provincial Regional Geochemical Survey, which has sampled and analyzed streams throughout British Columbia, has found numerous occurrences of natural acidic drainage (Lett et al., 1. Rapid sulphide oxidation in undisturbed areas is usually restricted to the thin, unconsolidated surface layer or to a few outcrops. Human activity can greatly enhance acid generation and metal leaching.
Sulphide oxidation resulting in very acidic p. H values is common worldwide in marine soils drained for activities such as farming (Pons et al., 1. ARD also occurs where mineralized bedrock is excavated for use in construction.
An example of this is some of the forestry road building on Northern Vancouver Island (Koyanagi and Panteleyev, 1. ML/ARD are major concerns for mining because most precious metal, base metal and some coal deposits in British Columbia are relatively rich in sulphide minerals, and because mining greatly increases the amount of rock surface exposed to oxygen and water.