Tailings Impoundment Closure Enhancement

Tailings Impoundment Closure Enhancement

Author: Amy Adams, Craig Hall, Ken Brouwer
Conference: CDA 2018 Annual Conference
Date: October 13-18, 2018

ABSTRACT
Many tailings impoundments provide long-term storage for saturated, semi-fluid fine grained materials. Closure of these tailings impoundments represents an ongoing priority and a potential challenge for owners and professionals due to the potentially fluid nature of the impounded tailings in the event of a hypothetical dam breach.

One solution is to cap and shape the impoundment surface using waste rock or other materials to promote surface runoff, minimize dusting, and densify the underlying tailings through consolidation. Poor surface trafficability can hinder capping operations, and the cap itself may not fully mitigate the potential for deeper saturated tailings to fluidize and flow in the event of a dam breach.

This paper provides a case study for the decommissioning of the Nye Tailings Impoundment at the Stillwater Mine. The closure plan includes capping the loose saturated tailings with waste rock along with a cover of surface soils to reclaim the impoundment and create a stable landform. Initial staged construction of the closure cap will be accomplished using a geotextile to improve trafficability during placement of the initial rockfill capping layer.

A potential opportunity to enhance the closure of the impoundment can be achieved through the progressive development of a large waste rock storage area over the capped tailings surface. This closure enhancement would provide significant storage capacity for waste rock and reduce additional site disturbance during ongoing mine operations. As an added benefit, the waste rock load would promote consolidation, densification, and dewatering of the underlying tailings, further reducing the potential for the impounded tailings to fluidize and flow in the event of a hypothetical dam breach. This integrated waste management strategy for the Stillwater Mine will provide operational benefits for ongoing waste rock management while concurrently developing a stable reclaimed post closure landform to enhance the reclamation objectives for the mine site.

 

Download the full technical paper.

Download

Recent Insights

September 2024
Importance of Indigenous Community Engagement related to ARD/ML and Long-Term Water Quality
September 2024
Effective Assessment of ARD/ML Potential for Non-Mining Infrastructure Projects
August 2024
CESA Aon Engineering Excellence Awards 2024: Kikagati Hydropower Plant
July 2024
Interview: Mario Lazo Emparanza, Regional Manager, Knight Piésold Chile
July 2024
Visionary Leadership: Driving Engineering Excellence in Africa with Vishal Haripersad
June 2024
Concept Feasibility and Predicted Behavior of Mining a Rock Tower with Drill-and-Blast Undermining Using Dynamic Three-Dimensional Discontinuum Numerical Models
June 2024
Estimating Shear Stress within a Clay Foundation Using the Burgers-Creep Model
June 2024
Laboratory Study of Manganese Mining Overburden Mixed with Lime as a Paving Subbase Layer
May 2024
Knight Piésold: Ensuring African Excellence in the DRC
May 2024
Wild Coast N2 Highway Project Taking Shape
May 2024
Interview: Guillermo Barreda, Gerente General, Knight Piésold Perú
April 2024
Risk Mitigation through Design Optimization Utilizing Seasonal Effects under Arctic Conditions at the Amaruq Mine
April 2024
Synthetic Rock Mass Modeling of Progressive Unravelling and Overall Slope Stability Using the Discrete Element Method
April 2024
Operational Slope Stability Risk Management for Large Open Pits at the Mount Milligan Mine – A Case Study
April 2024
Risk and Informed Approach to TSF Design and Operation
February 2024
Empowerment and Resilience
January 2024
Balancing Act: Water Usage Management Vital for a Sustainable Future
January 2024
A Difficult Balance Between Engineering, Environmental, Social and Economic Aspects
November 2023
Knight Piésold Commences with the ESIA for Haib Copper
November 2023
Insights from the Compilation and Critical Assessment of Breach and Runout Characteristics from Historical Tailings Dam Failures: Implications for Numerical Modelling