IMPROVING WATER MANAGEMENT IN THE MINING SECTOR PRESENTED BY: MATTHEW DAMHUIS IMPULSE WATER (PTY) LTD
Overview The Mining Life Cycle Types of Water Impacts from Mining Types of Water Impacts on Mining Current Mine Water Management Practices (RSA) Current Mine Water Management Practices (Africa) Potential Solutions for Improving Mine Water Management
The Mining Life Cycle Operational Phase Exploration & Construction Phases Exploration drilling Resource Determination and Modelling PFS/BFS Initial Mine Planning Construction (Camp, Plant, Mine etc.) Ore Extraction Processing Sale to Market Mine expansion Waste Generation Closure & Post- Closure Phases Rehabilitation of mined land Deconstruction of plant, camp etc. Care and maintenance of key infrastructure
Types of Water Impacts from Mining 2003 2015 Picture Credits http://www.environment.co.za/acid-mine-drainage-amd http://earthlife.org.za/campaigns/acid-mine-drainage/ https://en.wikipedia.org/wiki/acid_mine_drainage http://news.discovery.com/earth/one-cent-blocks-fishes-sense-of-scent-130705.htm Google Earth Imagery
Types of Water Impacts on Mining
Mine Water Management Practices (RSA) Principle legal framework for compliance (RSA) Constitution of the Republic of South Africa, 1996 (Act 108 of 1996) National Environmental Management Act (NEMA) (Act 107 of 1998) The Minerals and Petroleum Resources Development Act (MPRDA) (Act 28 of 2002) National Water Act (Act 36 of 1998) Various DWS Water Management Policies & Strategies (e.g. NWRS, CMS, WC/WDM etc.)
Mine Water Management Practices (RSA) Integrated Water Quality Management Model (DWS, 2008) Mine Plan Process Plant Water Requirements Stormwater Management Groundwater Management Waste Management Geochemistry INTEGRATED WATER MANAGEMENT MODEL Mine Water and Salt Balance IWWMP
Mine Water Management Practices (RSA) Challenges in the South African Mining Environment South Africa is a water-scarce country, thus availability of water for mining is limited and impacts potentially severe Mine water management generally reactive rather than proactive Water-related issues not always considered in early stages of mine planning and design South Africa s mining industry is older than its management legislation and frameworks. Thus the majority of issues faced by the country are due to older, abandoned mines. Auditor General (2009) estimated 5 906 abandoned mines in RSA, CGS estimated the rehabilitation bill would be ~R 30 billion of which ~R 28,5 billion would be to rehabilitate only 1 730 high-risk mines.
Mine Water Management Practices (RSA) Challenges in the South African Mining Environment (cont d) Most RSA mines in the operational or closure phase Abandoned, flooded mines near to operational mines, potentially contributing to cumulative impacts at the site Baseline conditions for the site would be impacted already Unrealistic RQO s set in some instances, where the natural, background water qualities are not taken into account (e.g. Steelpoort area, Waterberg area) Any updates would need to consider changes to the current operational philosophy at the site, potentially resulting in economic impacts for the mine
Mine Water Management Practices (Africa) Generally reactive management Limited legislation for water management Mine compliance is based on internal obligations, e.g. IFC standards or equator principles for listed companies Uncertain regulatory climate, thus capital expenditure is limited to essentials only Lack of environmental understanding (e.g. aquifer potential, river flow regimes etc.)
Solutions for Improving Mine Water Management Soni & Wolkersdorfer (2016) listed the following issues as essential for the improvement of water management in the mining sector: 1. Integrated environmental planning 2. Reliable mine water technology and mine water management 3. Proactive management of water quality 4. Increase the level of detail in water-related studies early in the operational phase 5. Reduce the oxidation of tailings and leaching 6. Mine water treatment solutions should be applied whenever economically viable 7. Pit lake development in post-closure is an effective and pragmatic end use for mine water, with sufficient stakeholder engagement and public acceptance
Construction Operational Closure Embedded Management Mitigation Unexpected Event Solutions for Improving Mine Water Management Proactive Water Management can be achieved through the implementation of an effective, realistic water management plan for the site. The Water Management Plan should be discussed in the following sections: Objectives; General Approach; and Water Management Controls (incl. embedded controls and mitigation measures). Issue/Component Objective Control Measure General Management Controls Training and Awareness Mine Water Management Comply with Relevant Standards and Legislation Make all employees aware of: water conservation/water demand management water pollution avoidance and minimization measures reporting procedure and registry of incidents
Solutions for Improving Mine Water Management Automated monitoring networks can be initiated at the site where data is transmitted to a central electronic database that is accessible to the on-site and head office personnel, as well as I&AP s at the site This allows for a secured, regular collection and transmission of data between all stakeholders at the site (e.g. mine staff, government bodies, surrounding water users etc.) The monitoring network database can be programmed to send alerts when certain parameters are exceeded (e.g. river flow rates, water levels etc.) Allowing for a proactive response to mitigate and manage impacts
Mine Planning Integration with Groundwater Modelling The current communication between mine planning & scheduling and groundwater modelling is time consuming and allows for human error during translation, with little communication between the mine plan and groundwater model Mine Design & Scheduling Data Processing & Preparation Numerical Groundwater Modelling
Mine Planning Integration with Groundwater Modelling The current method does not allow the mine to adapt to water increases with confidence, which potentially results in high OPEX costs relatively early in the LOM.
Mine Planning Integration with Groundwater Modelling Through integration of the mine planning and groundwater modelling processes, the mine may be proactive in its approach to dewatering planning and avoid high capital costs by allowing dewatering to be included in the operations budget when the mine is profitable The integration process also shortens the groundwater modelling process, allowing for continuous model updates without high project costs Mine Scheduling & Budget Development Mine Planning Groundwater Numerical Modelling
Mine Planning Integration with Groundwater Modelling By allowing the mine schedule to adapt to groundwater inflow conditions the OPEX for dewatering follows a more steady trend, allowing the mine to remain profitable and dry
Reduction of Oxidation and Leaching from Waste Storage Facilities Geochemical studies and classification of waste material should be completed in the early phases of the LOM Appropriate waste storage facility liner should be installed during the construction phase and appropriate emergency response measures identified in the site water management plan (e.g. spill response procedures) Where possible, concurrent rehabilitation of mining areas and waste disposal facilities should take place (e.g. contouring and vegetation of TSF walls) Wet beach areas limited at the TSF, where water is reclaimed by the processing plant
Water Treatment Solutions Contaminant of Concern Treatment Technology Arsenic Copper Lead Other Heavy Metals Fluoride Nitrate Activated Alumina X S X Granular Activated Carbon S Distillation X X X X X Anion Exchange X S X Cation Exchange X X S Ozonation Reverse Osmosis X X X X X X Other Adsorption Media X Electrodialysis X X X Ultrafiltration Ultraviolet Light Treatment solutions can be fully tailored and designed to meet the client requirements and budgetary needs. Some of the customisation options include: Treatment solutions can be fully containerised to allow mobility during operations Various treatment configurations can be combined to allow for the entire project objective to be met Sustainable power options can be investigated for the treatment solutions to allow minimal power requirements
Pit Lake Formation 6 1) Natural Environment 2) Mine Philosophy 3) Natural Processes 4) Natural & Management 5) Management 6) Results 5 4 3 2 1 After Castendyk & Eary, 2009.
Pit Lake Formation: Water Treatment Pump Treated Water Back into Epilimnion. Abstract Contaminated Water from Hypolimnion for Treatment. As Treated water gets pumped back into pit lake, the Epilimnion layer is expanding downwards, replacing Hypolimnion Layer. Pump Pontoon Pit Not Dewatered Pit Stability remains in place AMD Process After Castendyk & Eary, 2009.
References Auditor-General South Africa, 2009. Report of the Auditor-General to Parliament on a performance audit of the rehabilitation of abandoned mines at the Department of Minerals and Energy. Castendyk, D.N. and Eary, L.E., 2009. Mine Pit Lakes: Characteristics, Predictive Modeling and Sustainability (Volume 3). SME, Colorado, USA. Department of Water & Sanitation (DWS), 2008. Best Practice Guideline H1: Integrated Mine Water Management. Government Printers, Pretoria, South Africa. Soni, A.K. & Wolkersdorfer, C., 2016. Mine water: policy perspective for improving water management in the mining environment with respect to developing economies. International Journal of Mining, Reclamation and Environment, 30:2, 115-127, DOI: 10.1080/17480930.2015.1011372
Thank You JOHANNESBURG The Pivot - Ground Floor, Block E No. 1 Montecasino Boulevard Fourways, Gauteng Contact: Matthew Damhuis Tel: +27 11 568 2100 Mobile: +27 82 684 0801 matthew@impulseint.co www.impulsewater.co