Managing our tailings storage facilities
Creating and storing tailings has long been an integral part of mining operations.
Tailings are the residue which remains after extracting minerals and metals from mined ore. The waste can take the form of a liquid slurry comprising finely milled ore, water, trace quantities of metals and additives used in processing. This residue is typically stored on surface in structures called tailings storage facilities (TSFs) where it is managed to protect human health and the environment, while enabling efficient and responsible production. Tailings residue can also be placed in mines as backfill.
If these facilities are not managed effectively, structural failure or tailings overtopping could result in significant adverse impacts on the environment and human health and safety. TSF rupture can endanger the lives of employees and communities, result in water and soil contamination, or destroy downstream ecosystems.
With the pollution from effluent and dust emissions being potentially harmful to humans, animals or plants, TSF management is a crucial aspect of any sustainable operation.
With our ultimate goal of zero harm to people and the environment, we have an obligation to ensure our mine tailings are stable, non-polluting and contained.
Our tailings management system is designed to help ensure that risks are identified, recorded and mitigated. Our management approach incorporates mechanisms for reporting risks and tracking mitigation measures with communication delivered to all levels within the business. Our Board and Executive members are kept informed of the status of our TSFs through regular reporting.
AngloGold Ashanti manages 27 TSFs, with 19 active TSFs, eight of which receive filtered tailings, seven inactive (dormant) TSFs, and one new facility that is under construction.
Our TSFs are designed and built to a rigorous set of standards and are carefully managed and monitored through a four-layered assurance system by a team of internal specialists and independent external experts.
1. Operational management
- A TSF operator/superintendent manages the day-to-day operation at the TSF
- A plant or process manager is the TSF “owner” responsible for implementing requirements of the TSF operating manual
2. Business Unit management
- Provide technical guidance to operations
- Conduct quarterly inspections of active TSFs
- Monitor implementation of recommended actions
3. Corporate management
- Custodian of Tailings Management Framework
- Conduct formal TSF audits annually or biennially
- TSF review for projects and for mergers and acquisitions
4. Independent review
- Independent tailings facility review per the GISTM
Information relating to the status of each of our TSFs is disclosed on our website.
Progress in 2022
Despite the challenges placed on our tailings management resources given the global shortage of qualified personnel, we continued our progression toward conformance with the GISTM in 2022, with the aim of either meeting its requirements, or demonstrating a credible plan to meet them. Engineers of record have been appointed at all of our operations and independent tailings review Board inspections have been conducted at our operations in Africa and Australia. Bi-annual independent stability declarations are already a requirement for our Brazilian TSFs and we will formally appoint independent review Boards for our Brazilian and Argentinian operations in 2023.
In Australia, Tropicana’s environmental licence was amended to increase the design capacity of its TSF. At present, the facility is within the original design capacity.
Responding to tailings management legislation in Brazil
In response to the regulatory changes in Brazil, which followed the Brumadinho TSF failure in 2019, our Brazilian operations began the mandatory decommissioning of existing TSFs by transitioning to filtered tailings deposition. This transition was completed during 2022. As part of their closure design, filtered tailings are used to fill and reprofile the surface of these facilities. We have also introduced new filtered tailings deposition areas as part of the current and future deposition.
In parallel, our Brazilian operations were required to develop and roll out an augmented TSF-related emergency preparedness protocol across all downstream communities that may be affected by a potential TSF emergency. The experience in Brazil has been shared internally within AngloGold Ashanti operations and externally with ICMM peers. It has also inspired the development of a Company-wide TSF Emergency Preparedness Response Plan (EPRP) protocol, leveraging learnings from Brazil that can sensibly be applied across AngloGold Ashanti operations.
The introduction by the Brazilian Mining Agency (ANM) of new regulations in February 2022 consolidated all TSF-related safety regulations and guidelines in Brazil. Several new obligations were introduced for TSF Operators, including the requirement to have external consultants periodically certify the geotechnical stability of all TSF structures and that emergency response plans and related infrastructure, such as emergency alert sirens, fully meet legal requirements. In late 2022, tailings deposition was required to be suspended at five of our TSFs in Brazil pending completion of additional work required to obtain these mandatory certifications.
Another new requirement was to conduct and submit facility-specific risk assessments by December 2022 and thereafter update the risk assessments every two years. One of the outcomes of these risk assessments was to increase buttressing of the Calcinados TSF, which services the Cuiabá Mine Complex in order to align the TSF’s safety factor with international standards, currently considered best practice. The operational integrity of the Calcinados TSF remains sound, in line with recent assurance assessments by independent geotechnical specialists and AngloGold Ashanti’s own tailings experts.
Our Brazilian TSFs have 24-hour video surveillance, and undergo constant inspections and monitoring, which are intensified during the rainy season. The Company has also installed new piezometers to further enhance TSF monitoring. Importantly, AngloGold Ashanti Brazil continues to engage closely with regulators, local communities, authorities and other stakeholders.
Progress in Ghana
In Ghana, the construction of the Beposo TSF at Iduapriem is on track for commissioning in 2023 and will coincide with the decommissioning of the Greenfields TSF. The inactive Kokoteasua TSF at Obuasi is being reclaimed to boost the supply of backfill material used to support underground mining. This forms part of the closure approach for Kokoteasua. The closure design for Obuasi’s inactive Pompora TSF continues and geotechnical field and laboratory testing was conducted in 2022.
In Tanzania, Geita’s TSF will initiate the construction of their next wall raise in late 2023. Its design is currently in progress.
We are developing a Company-wide TSF monitoring portal and have successfully initiated the use of interferometric synthetic aperture radar (InSAR) satellite technology for TSF displacement monitoring. The use of drones for survey and imaging is being implemented across all of our operations.