Chapter 7

7. Drainage Treatment
Last Update: July 2021

GARD Guide Chapter 7

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Sustainable mining requires the mitigation, management and control of potential mining impacts on the environment. The potential impacts of mining on water resources can be long term and persist in the post-closure situation. Mine drainage treatment may be a component of overall mine water management to support a mining operation over its entire life.

Once an ARD problem exists, various treatment options may need to be considered to prevent ARD from impacting nearby social or environmentally significant receptors. This chapter discusses these technologies in terms of mine water treatment, evaluation and selection of treatment technologies, implementation of each technology and ancillary (pre-treatment, polishing, and support systems) requirements for a specific mine project. Classifications for both active and passive treatment technologies are presented. Background and descriptions of each technology are provided with supporting and additional information to evaluate whether the technology is a candidate for a specific mine water treatment application or a specific mine water contaminant. The sections on active and passive treatment primarily discuss proven mine water treatment technologies; however, a final subsection on emerging technologies is included in each section.

Table of Contents

  • 7.0 Mine Water Treatment
  • 7.1 Introduction
  • 7.2 Risk-Based Approach
  • 7.3 Setting Objectives for Treatment
  • 7.4 Water Collection and Treatment Approach
    • 7.4.1 Source Identification and Characterization
    • 7.4.2 Water Collection and Management
  • 7.5 General Constraints for Technology Selection
    • 7.5.1 Applicability of Active versus Passive Treatment Systems
    • 7.5.2 Temperature
    • 7.5.3 Area/Real Estate Available for Treatment
    • 7.5.4 Constituents, Speciation, and Antagonistic Effects
    • 7.5.5 Regulatory requirements
  • 7.6 Evaluation and Selection of Drainage Treatment Technologies
  • 7.7 Active Treatment Technologies
    • 7.7.1 Flow Equalization (Flow and TSS)
    • 7.7.2 Oxidation and Precipitation (Acidity and Metals)
    • 7.7.3 Membranes (TDS, Sulfate, and other Dissolved Constituents)
    • 7.7.4 Evaporation (Mechanical and Pond/Enhanced)
    • 7.7.5 Ion Exchange and Adsorptive Media
    • 7.7.6 Biological (Selenium, Nitrogen Species)
    • 7.7.7 Gravity Separation (TSS, Oil and Grease)
    • 7.7.8 Filtration and Membranes for Solid-Liquid Separation (TSS and Oil and Grease)
    • 7.7.9 Advanced Oxidation (Cyanide and other N-species)
    • 7.7.10 Emerging Active Technologies Considered in MIW Treatment
  • 7.8 Passive Treatment Technologies
    • 7.8.1 Constructed Wetlands
    • 7.8.2 Biochemical Reactors (BCRs)
    • 7.8.3 Reducing and Alkalinity-Producing Systems
    • 7.8.4 Anoxic Limestone Drains
    • 7.8.5 Open Limestone Drain
    • 7.8.6 Limestone Leach Beds
    • 7.8.7 Manganese Oxidation Beds
    • 7.8.8 Emerging Passive Technologies
    • 7.8.9 Development of a Passive Treatment Train
  • 7.9 In Situ and In-Mine Treatment Technologies
    • 7.9.1 Alkaline Injection
    • 7.9.2 In-Pit Treatment
    • 7.9.3 Underground Treatment
    • 7.9.4 Permeable Reactive Barriers
    • 7.9.5 Saturated Rock Fill
  • 7.10 Management of Residuals
    • 7.10.1 Sludge Management
    • 7.10.2 Brine Management
  • 7.11 Resource Recovery
  • 7.12 Approach to Costing
  • 7.13 Treatment in the Context of Mine Closure and Post Closure
  • 7.14 Case Studies and Sources of Additional Information
    • 7.14.1 Sources of Additional Information
    • 7.14.2 Case Studies for Active and Passive Treatment
  • 8.0 References
  • List of Tables
  • List Figures