Innovative Tailings Management
Innovative Tailings Management
Context
Tailings management is one of the most pressing environmental and operational challenges in mining. Traditional wet tailings facilities require large volumes of water and can pose significant stability and safety risks, particularly in water-scarce regions. Failures can have severe social, environmental, and economic consequences, leading to stricter global standards such as the Global Industry Standard on Tailings Management (GISTM).
With growing water scarcity and heightened ESG requirements, the industry is seeking cost-effective technologies that can both conserve water and improve tailings stability.
One example is Hydraulic Dewatered Stacking (HDS), a patented technology first piloted in Chile and now being trialed in Southern Africa.
Challenge
Mining operations worldwide face multiple challenges in tailings management, especially in water-stressed environments:
- Tailings stability: Traditional storage facilities created for wet tailings can cause major risks to the communities and the environment, and can potentially lead to failures and mudslides
- Impact on the environment: Tailings dam spillage has an adverse impact on the environment as they cause contamination of the soil, water bodies and the entire ecosystem with hazardous waste such as heavy metals and chemicals. Ameliorating these effects requires costly remediation efforts[iv]
- Regulatory compliance: Global Industry Standards on Tailings Management (GISTM) are industry standards with stringent compliance requirements and ensuring that mines adhere to them requires finding ways to keep tailings facilities stable and safe in the long-term[v]
- Economic Viability: Mining projects are generally capital intensive, but in absence of financing, it is important to discover ways to innovate cost-effective solutions to ensure economic viability, particularly for managing tailings
Approach
Anglo American developed Hydraulic Dewatered Stacking (HDS), a desaturated tailings storage method that combines coarse particle recovery (CPR) with innovative deposition techniques to improve both water recovery and facility safety. [vi] The technology's features include:
- Innovative technology: Use of fines-free sand generated by coarse particle recovery to create a drainage network within the tailings mass, allowing for rapid dewatering and consolidation
- Water recovery: The technology works in a way that allows water entrained in the tailings to be recycled and this ends up reducing the demand for fresh water. This has a positive effect on regions suffering from water scarcity
- Enhanced stability: HDS helps in improving the safety and stability of tailings storage facilities by dewatering the tailings and eliminating the surface pond. Even in the case of a failure of the facility, the lower interstitial water content reduces the potential for mudslides
- Cost-effective implementation: By offering solutions without a need for high capital expenditure, it is a more economical way to tackle the problem of wet tailings when compared to other thickened and filtered tailings technologies
- Progressive closure: Cells-based approach to tailings deposition allows for progressive closure and reclamation over the life of the mines. The need for long-term monitoring is reduced by the free-draining nature of HDS tailings that minimize the risk of re-saturation and long-term seepage
Conditions
The development and implementation of HDS benefited from:[vii] [viii]
- Technological innovation: Successful implementation of CPR technology, which helped in providing fine-free sand needed for the drainage network
- Successful collaborations: Joint development with engineering firm WSP.
- Regulatory support: Facilitation from Chile’s Ministry of Mining and Sernageomin (National Geology and Mining Service)
- Research and development: Laboratory trials conducted extensively, concept studies and field trials conducted, helped in refining the HDS technology, ensuring its feasibility
- Supporting infrastructure: Construction of a bespoke HDS tailings facility and extensive instrumentation for data collection and monitoring, helped in providing the necessary infrastructure and validation
Observed Impact
HDS has been successful in achieving a wide-ranging impact, particularly in achieving water saving in a water-constrained environment:
- Water conservation: High levels of water recovery, i.e. >80% of tailings water being recycled back to the mine, has been demonstrated, which reduces the demand for fresh water[ix]
- Potential transferability: Successful testing in Chile allowed for the technology to be piloted at the Mogalakwena Platinum Mine in South Africa, which will be the first brownfield application of HDS, which would be scaled up to the world’s first large-scale HDS facility[x]
- Improved safety: Reduced potential for failure and mudslides through desaturation.
- Economic efficiency: Lower capital and operating costs compared to other advanced tailings technologies.
What’s Next for the Southern African Region
This case highlights how Hydraulic Dewatered Stacking could be applied more broadly across Southern Africa to strengthen responsible mining practices:
- Tailings management: Use of HDS could improve water conservation and the safety and stability of tailings storage facilities
- Collaborative development: Forging partnerships among mining companies, engineering firms and government agencies is key to promote innovative technologies
- Water sustainability: To improve the environmental footprint of mine operations and comply with global ESG standards, it is necessary to prioritize water recovery and recycling, that also enhances water sustainability
[v] https://www.e-mj.com/features/turning-the-tide-on-tailings-creating-opportunities-rather-than-risks/
OTHER SOURCES
https://www.wsp.com/en-ae/projects/el-soldado-and-hds
https://www.wsp.com/en-ae/insights/innovation-in-tailings-dewatering
https://www.insightterra.com/case-studies/anglo-american