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Tailings management

At MMG, the safe and responsible management of tailings and Tailings Storage Facilities (TSFs) is a critical material issue and a core component of our environmental and social risk management. Our approach is embedded in our dedicated Tailings Storage Facilities and Water Storage Dam Standard, and as members of ICMM, we are committed to reporting in line with global frameworks, including the Global Industry Standard on Tailings Management (GISTM). 

Governance and Risk Management 

Tailings management is governed at the highest levels of the organisation, with oversight from the Executive Committee and the Governance, Remuneration, Nomination and Sustainability (GRNS) Committee of the Board. Our governance framework includes: 

  • Engineer of Record (EoR) assigned to each TSF 
  • Independent Technical Review Boards (ITRBs) for high-consequence facilities 
  • A dedicated Accountable Executive, who receives monthly updates about the status and performance of each TSF across MMG  
  • Annual risk assessments and third-party audits 
  • Emergency preparedness and response plans aligned with GISTM 

In 2024, MMG completed independent reviews of all active TSFs and updated risk registers in accordance with GISTM and the ICMM Performance Expectations. 

Design, Construction and Operation 

MMG’s TSFs are designed and operated in accordance with: 

  • GISTM 
  • Australian National Committee on Large Dams (ANCOLD) 
  • Canadian Dam Association (CDA) 
  • Mining Association of Canada (MAC) 

Most of MMG’s TSFs, including Las Bambas, are constructed using downstream or centreline methods. At Rosebery (Australia) and Khoemacau (Botswana), upstream construction is used in limited areas, with enhanced monitoring and controls in place. 

All TSFs undergo: 

  • Daily inspections by site teams 
  • Monthly performance reviews 
  • Annual dam safety inspections 
  • Five-yearly third-party audits 

In 2024, MMG managed over 329,810 cubic metres of tailings across 8 active TSFs. 

GISTM Alignment and Public Disclosure 

MMG is committed to full alignment with GISTM. In 2024: 

  • 100% of active TSFs were assessed against GISTM 
  • Site-specific implementation plans were developed and published 
  • Public disclosures were updated in our Sustainability Report and ESG Databook 

GISTM’s six topic areas are fully integrated into MMG’s tailings governance: 

  1. Affected Communities 
  2. Integrated Knowledge Base 
  3. Design, Construction, Operation and Monitoring 
  4. Management and Governance 
  5. Emergency Response and Long-Term Recovery 
  6. Public Disclosure and Access to Information 

Community Engagement and Emergency Preparedness 

We engage with host communities and regulators to ensure transparency and preparedness. This includes: 

  • Community briefings on TSF safety and emergency response 
  • Joint emergency drills with local authorities 
  • Accessible grievance mechanisms for tailings-related concerns 

In 2024: 

  • Over 300 community members participated in emergency response exercises at Las Bambas and Kinsevere 
  • Zero tailings-related grievances were escalated beyond site level 

Closure and Post-Operational Planning 

Tailings management is integrated into MMG’s mine closure planning, with a focus on: 

  • Safety for community and wildlife. 
  • Long-term stability 
  • Non-polluting (e.g. water and air quality) 

 Self-sustaining and aligned to the post-mining land-use. In 2024, MMG did not decommission any TSFs or initiate post-closure monitoring. MMG continues to undertake detailed studies to understand how to ensure safe closure of our Tailings Facilities. 

Climate Risk and Financial Assurance 

We assess climate-related risks such as extreme rainfall in TSF design and monitoring. These risks are integrated into our enterprise risk management (ERM) framework and disclosed under TCFD. 

MMG maintains adequate financial provisions for the safe closure and rehabilitation of TSFs, aligned with IFRS S1 and GRI 201, and reports aligned with global frameworks including GISTM, Global Reporting Initiative (GRI) 306, Hong Kong Stock Exchange (HKEX) Environment, Social and Governance (ESG) Code, and International Financial Reporting Standard (IFRS) IFRS S1/S2. 

Reporting and disclosure 

As a member of ICMM, MMG is committed to tailings governance transparency and alignment with GISTM disclosure requirements. In August 2025, we will disclose a GISTM-aligned report for all our TSFs (with the exception of Khoemacau, which we will disclose by 2029 in accordance with the provisions as set out in GISTM post the acquisition of new assets). In late 2025, we will undertake third-party assurance of each site’s GISTM action plan to ensure we continue to improve our processes and will further update our stakeholders on our progress in 2026.   

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