Tailings storage facility (TSF) design has long been based on deterministic limits. By extension, the TSF owner accepts a Probability of Failure (PF) associated with these deterministic limits which are assessed against industry norms with respect to investigation/analysis and design assumptions related to the operation of the facility. If the Probability of Failure of a design that is derived in this way is taken as the likelihood related to the tolerable risk limit, it follows that the same, or a lower PF, should be maintained during operations. Examples of operational controls include pond management and inspections/monitoring. Upset conditions arise when operational controls are not being implemented. Therefore, by comparing the calculated PF of the TSF complying with the design assumptions and the PF for the same TSF in an upset condition, the required PF of operational controls can be estimated. This concept assists the TSF owner in determining what is required to safely operate the facility and communicate the geotechnical risk to all stakeholders. By extension, scenarios where a TSF owner cannot achieve the required PF of operational controls can be addressed with: 1. Greater rigor applied to operational controls. 2. Addition of more operational controls. 3. A change to the design assumptions, where the timing of the project allows. This method provides a measured approach to risk management in the design and operational phases, without a TSF owner having to quantify an acceptable risk tolerance. Instead, the design is based upon widely accepted practice and industry/business accepted safety, economic and environmental risk levels. Subsequently, the design PF can be calculated and then applied as a benchmark for operations. This approach serves to reduce uncertainty through alignment of the design and operation phases. The concept is explored for three different tailings storage methods: upstream raised TSF, downstream raised TSF, and impoundment by mine waste dumps, to estimate how sensitive each storage method is to the type and effectiveness of operational controls implemented by the dam owner.
This bulletin discusses common problems in the disposal of tailings at mines, quarries and other industries, and identifies safe methods of designing and operating dams and impoundments. The problems encountered at the end of operations when it becomes desirable to end tailings dam construction and it is necessary to rehabilitate the dam and its impoundment to make it permanently safe and environmentally acceptable are discussed and a final chapter describes some of the governmental regulations controlling tailings dams in some countries.
This bulletin deals with: Location of dams, Site investigation, Design, Construction and operation, Closure and abandonment
This bulletin is intended primarily for the use of the Regulatory Agencies responsible for the safety of tailings dams, both structurally and environmentally. However, it is also intended to assist the mine operator in understanding the measures that must be adopted to ensure that his tailings dam is safe, both during operation and after rehabilitation. Finally, it should also benefit those individuals or organizations involved in the design, construction, operation, and rehabilitation of tailings dams.
The Graduate Certificate in Tailings Management is comprised of 12 two-point micro-credentials. Students may apply for the Graduate Certificate in Tailings Management after successfully completing all 12 micro-credentials and associated assessments. The courses include: Introduction to Tailings Management, Tailings operations and Water Management, Tailings Risk Evaluation, Tailings Governance.
There are gaps in board assurance on technical and operational risk in mining. There are gaps in current environmental social governance (ESG) and enterprise risk management, especially for geotechnical risk. Chief risk officers (CROs) and audit teams who report to the boards audit and risk committee are often staffed by accountants and lawyers who provide an essential service, but may not appreciate the science, technology, engineering and maths (STEM) aspects of mining, including its technical complexity, variability and uncertainty. This demography tends to focus on commercial, financial and legal risk. Their skill sets mean they may have a blind spot on how STEM mining risks have an impact, including on company performance and innovation (opportunity risks). Additionally, with the digital transformation of mining underway, there is a risk the disrupting digital natives (i.e. deep domain experts on digital technology) also lack an understanding of the technical and operational risks of mining and may inadvertently create new risks. Understanding risk in mining requires technical and operational expertise in mining engineering, life-of-mine planning, geotechnical engineering, geology and metallurgy. These professionals need to work alongside traditional risk practitioners and auditors to develop new ways to provide transparency, accountability and assurance to mining company boards.
Rio Tinto Iron Ore operates 16 different mine operations in the Pilbara region of Western Australia. Across these operations, there could be more than 100 operational open pits at any given time. This poses a considerable challenge for the effective management of geotechnical risks with finite resources. There are also a number of external legislation and internal compliance requirements that need to be adhered to. A number of standardised systems and tools have been developed by the geotechnical teams to manage the geotechnical risks and this paper introduces the different components of Rio Tinto Iron Ores geotechnical management System (GMS). The GMS covers the complete process, from the geotechnical design of a slope, through implementation to verification of performance and feedback to the design engineer. The focus of the paper will be on the Geotechnical Risk and Hazard Assessment Management System (GRAHAMS) which is used to assess and document the safety and economic geotechnical risk assessments of different slope areas. A number of reports and visual summaries of the risk assessments are available in the system, offering leaders the opportunity to identify areas of elevated risk and allocate resources accordingly. Details of realised risks (geotechnical hazards) are also captured and GRAHAMS provides a process to communicate the hazard and relevant controls to operational personnel. The GRAHAMS system was recently enhanced, moving from a Microsoft Access front-end to a web-based platform. This will enable a number of system improvements to further increase its effectiveness.
It took five years to bring mining with paste backfill to Maaden Barrick Copper Companys (MBCC) Jabal Sayid Mine in Saudi Arabia. The work involved various studies, multiple test programs, site visits for benchmarking and detailed engineering before the paste system was commissioned in October 2017. Barrick is a world leader in paste backfill and drew on international teams to conceptualise, design and construct this 225 m3/hr cemented paste backfill system. Value engineering, peer reviews and risk management workshops were held throughout the process to ensure MBCC received value for money and a reliable system. The paste plant was required to handle a tailings stream that was originally planned to produce hydraulic fill (the coarse fraction) but through the reintroduction of fine tailings was able to generate a good paste product that met mining needs. Challenges involved getting the most out of the tailings dewatering circuits (both fine and coarse streams), the local conditions (temperatures >50°C), large bulk stopes fed by a gravity system and the capital cost associated with building a high throughput system with significant cement storage. This paper presents the history of the project, test work, engineering design and construction, commissioning, and training required to fill the first stope. More recent backfill monitoring, data logging, improvements and ongoing optimisation of the system that have continued through the first year of paste production are also presented.
Operational control and trigger action response plans for tailings storage facilities (TSFs) routinely measure a number of operational aspects to assess risk and ensure the TSF does not exceed certain design considerations. Measurements that are routinely used for this purpose include topographical surveys and beacon settlements, density and moisture measurements, and discharge characteristics, among others. A statistical analysis of the cumulative historical operational datasets from a TSF allows improved knowledge of the level of variability of the considered parameters, and potentially enhances risk-based decisionmaking by increasing the understanding of uncertainties and the potential for expected deviations during operations (ICMM 2021). The inclusion of a probabilistic dataset in the design inputs allows a performance-based approach to managing a TSF, considering a series of scenarios defined by performance objectives, determining key factors to identify them in a timely manner, and incorporating effective corrective or failure control measurements, that can be improved with sequential forecasts of the TSF behaviour. This approach was undertaken to optimise the deposition strategy of the Cerro Vanguardia TSF and expand its life-of-mine (LOM), allowing for tighter construction planning and deferral of construction by several years. This had considerable benefits during the current COVID-19 contingency. Statistical analysis of ongoing operational monitoring data was adequately incorporated into operational design optimisation and to select an adequate level of risk tolerance based on an as low as reasonably practical (ALARP) perspective. Performance-based scenarios were identified and plans for timely decisionmaking were established to forecast reasonable economical/financial planning, and a probability-based events selection to trigger timely operational adjustments.
AusIMM, in conjunction with leading experts in the mining industry, has developed the Professional Certificate in Tailings Management. Featuring internationally-renowned tailings experts and case studies, the course will cover geotechnical, geochemical, governance, closure and socio-economic considerations of tailings management. The interactive, online format of the course will provide participants with an opportunity to learn in a community-based environment from wherever they are situated.