Improving the Safety of Mining Tailings Dams

7 min read

By Sam Aubry

Consultant

On Thursday 25th January 2019 a tailings dam at Vale’s Córrego do Feijão mine in Brazil burst open with catastrophic effects. Over 200 people lost their lives, many of them Vale workers. Over 270 hectares of land were also destroyed, including protected forests, leading to Brazil’s largest environmental disaster to date.

Unfortunately, tailings dam failures happen too often with the number of failures having doubled in the past 20 years. According to World Mine Tailing Failures (WMTF) without changes to regulations and industry practices, as well as investment in new technology, there will be 19 ‘very serious failures’ between 2018 and 2027.

Tailings dams have been a popular disposal system for mining waste over the last 100 years due to their cost effectiveness and size. With an estimated 3,500 active tailings dams globally ensuring they are designed, constructed and managed safely is vital for saving lives and avoiding catastrophic environmental damage.

With mining companies facing increased scrutiny over the safety of tailings dams and pressure to improve their safety and reliability, how can the industry reduce the number, and severity, of tailings dam failures?

1. The industry needs to establish new international standards

According to WMTF, major changes to regulations and industry practices are needed to reduce tailings dam failures. Following the disaster in Brazil, the UN Environment Programme, the International Council on Mining and Metals and the Principles for Responsible Investment instigated a Global Tailings Review to establish an international standard for the safe management of tailings dams. This video explains in more detail what the Global Tailings Review hopes to achieve.

 

These new standards will not only be instrumental in preventing failures but also crucial to rebuilding trust in the industry. The biggest challenge will be ensuring swift implementation and adoption once the review has completed its findings in 2020. Whilst the new international standard will be mandatory for all ICMM company members, it won’t be compulsory for other companies. The process is being conducted collaboratively with the industry, which will hopefully encourage the adoption of the new standards in every business.

2. The investment in alternative disposal systems, new mining methodologies and technology must continue

Tailings dams are more unstable than water-retention dams due to the way they are constructed. They are built using earth and rock rather than reinforced concrete as part of their structure. Many tailing dams are built using the “upstream” method too, which is cheaper to construct but also much more likely to fail. As a result, the industry has been developing alternative systems to reduce the reliance on tailings dams. These include paste disposal, filtered tailing disposal and thickened tailing disposal. All these options also optimise water recovery, which helps reduce the environmental impact of mining. 

Whilst these are interesting alternatives, there isn’t a perfect solution that will work for every mine regardless of size, climate or topography. Continuing to invest in new methods of mining waste disposal is essential for avoiding future catastrophic failures. Companies also need to be open to the most suitable option for their mines rather than the cheapest.

In recent years there has also been a focus on different mining methodologies that require less water, such as HPGR and dry tailings, meaning there is less strain on tailings dams and they can be smaller in size. Again, companies need to be open to the most suitable mining methodology based on the unique circumstances each mine presents.

Advancements in technology are also being used to improve safety through improving the monitoring and surveillance of tailings dams. As tailings dams are raised in stages, conditions can change over time leading to a failure. They should be monitored closely even when they are no longer active. Dr Caius Priscu – Head of Mineral Residue Facilities at Anglo American – is a supporter of using technology in this way: “There has been a step-change in surveillance performance through the introduction of satellite-based technologies. We are now able to measure much more accurately, and in real time, movements and deformations over time in dam behaviour, with measurements being made available on a computer screen or mobile device, anywhere in the world.”

3. The perception of tailings dams as a cost that can be reduced has to change

For many in the mining industry, tailings dams are considered to be a ‘cost’ to the business. With middle management often incentivised to reduce costs and raise production, this can encourage tailings dams to be built as cheaply as possible with minimal innovation in technology and processes.

Companies need to see the safety of tailings dams as a business priority requiring investment rather than as a business cost. Cost-saving targets should not be associated with tailings dams, instead opting for safety and reliability based KPIs to encourage investment.

4. The level of accountability needs to be improved

Due to the devastating impact of tailings dam failures, they need to be a high priority for mining businesses. Having a senior-level individual responsible and accountable for stopping tailings dam failures is crucial to making sure it stays at the top of the business’ agenda. A recent report from CDP showed only 26% of respondents’ tailings dams risk management procedures have any form of approval by a C-suite officer. Without this senior-level approval and accountability, procedures may not be followed and there is no one pushing for the innovation and investment needed.

5. The industry needs to invest in the talent it needs

For tailings dams to be constructed, managed and maintained properly, we need to invest in those with the right skills sets for the industry. From having many conversations with industry leaders, I believe a skills shortage is emerging within geotechnical engineering, partly due to the cyclical nature of the mining industry but also because there is an old-fashioned image associated with the sector. We need to work hard to rebrand and make mining an attractive proposition for new graduates. Attracting young people to work in mining, as well as providing enough development and incentives for those qualified individuals to remain in the industry, is a big challenge at present.

There are also new roles developing in the mining sector with different skill sets as the industry adapts to new technology. Companies need to be able to attract talent that can help them lead the way in innovation and as a result, find new and innovative solutions for mining waste disposal.

If you would like to discuss your thoughts on this topic and how it may have affected your company's talent needs, then contact me on nadia.amoura@csgtalent.com.

References

CDP, Risk and the Mining Industry After the Brumadinho Tailings Dam Failure

Industriall Union, Why you Need to Know About Tailings Dams 

Reuters, Column: Brazilian Mine Tragedy Will Not be the Last Tailings Dam Disaster

Science Direct, Why Have so Many Tailings Dams Failed in Recent Years?

Financial Times, Business as Usual Not an Option For Management of Tailings Dam

Anglo American, Challenges of Working in Mining

Mining Technology, Time to Talk About Tailings Dams

Stantec, Alternative Tailing Disposal - is it the 'Silver Bullet' for Mine Waste