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Sand Processing, Recycling, Case Studies

A CDE AggMax logwasher in operation.
A CDE AggMax logwasher in operation.

Engineering the tail end of tailings

CDE Global’s Adam Holland discusses the quest to eliminate the tailings pond.

My job is never boring. I have been travelling around the world for a year, visiting mining sites in Latin America, Australia, Africa and Ireland to discover what makes each of them tick and find the most efficient ways to bring optimal yield and minimal waste. When it comes to tailings dams, I have seen the good, the bad and the ugly.

So much has been written about the viability of dams and the dangers associated with them, but there is still a long way to go in terms of stepping back from mere observations and consolidating empirical research to allow the development of foolproof solutions.

The more we understand about them, the more we can bring the perfect mining waste management solution to mining operators, with a view to eliminating the need for tailings dams thanks to advancement in materials wet processing technology.

The total number of active tailings impoundments was loosely estimated at 3500 in a variety of reports in 2012, but this figure is disputed and no up-to-date evidence-based data exists to allow solid comparative research of the actual impact tailings dams across the world have on the environment. Correlatively, this means piecemeal solutions are the norm until a global approach to mining pollution can be considered. But piecemeal is not good enough in times of crisis.

Alarm bells have been resounding across the mining industry for years, as numerous tailings dam failures have resulted in unspeakable damage to the environment and to the lives of thousands.

Dam collapses have been affecting mining operations indiscriminately throughout the world, from the Philippines to Russia, Brazil and the United States, to name just a few.

"The more we understand about them, the more we can bring the perfect mining waste management solution to mining operators."
Adam Holland, CDE Global

On a trip to Brazil in August to make the case for iron ore tailings management and beneficiation with CDE clients, I witnessed how the Samarco disaster has reshaped environmental legislation in Brazil, which is now focused on active prevention coupled with remediation.

The Samarco iron ore mine is a case in point when it comes to lessons learned from a disaster that was widely covered by the media in 2015.

As the company took stock of the consequences of the dam’s failure on the socioeconomic and environmental make-up of the region, this initiated comprehensive solution-led research with a view to ensuring it could never happen again.

The Renova Foundation, created after the Samarco disaster to make sense of the tragedy and provide a practical solution to human, environmental and industrial challenges, sets the tone of action: knowledge-based restoration, reconstruction, production, all three strands being addressed in synergy to allow for a comprehensive solution.

In the context of the Brazilian government’s renewed focus on fighting waste pollution and turning every ounce of the Earth’s resources into valuable materials, it is timely for CDE to contribute to the edifice of change by developing bespoke modular tailings management and beneficiation solutions that contribute to restoring faith in the benefits of mining operations for the local economy and turning mining waste into revenue or materials for use in environmental rehabilitation.

In doing this, CDE seeks to repeat the success of its projects with Brazilian mining operator Vallourec in Brazil. Ahead of the curve for tailings recovery and remediation in the region, Vallourec and CDE have developed and successfully run a dewatering system that has rehabilitated a tailings dam, helping to change the mindset towards tailings management by utilising recovered solids in ground remediation and road brick manufacture.

The proof is in the process: six EvoWash washing units dewater 30,000 tonnes per month of materials that are stockpiled as a dry product. Two banks of cyclones remove 30 per cent of the mass (15,000 tonnes per month) to a filter press. The resulting cakes are used in soil composition and road brick manufacture. Strikingly, this bespoke modular wet processing solution allows for 45,000 tonnes of material to be diverted from Vallourec’s tailings dam on a monthly basis.

On the strength of this significant achievement in Brazil – the process being replicated with adequate materials and needs-based variations across the world – CDE is working on becoming a positive actor in the clean-up effort emanating from the Samarco legacy. As the business continues to develop ever more efficient means to manage tailings while adding value to mining operations, modular tailings recovery systems are set to become the next priority for companies under pressure to meet both their business and environmental targets.

CDE’s “New World of Resource” ethos runs through every strand of the business, embedding a commitment to reduce waste and remediate and turn it into value. Not only do CDE’s patented technologies allow for clean and energy-saving materials wet processing operations, but the company’s innovative approach to waste management also opens up a new world of possibilities that involve the transformation of waste into high value construction products while ultimately eliminating the need for settling ponds and tailings dams.

Nanowash mini-cyclones on an iron ore wet processing plant at Vallourec, Brazil.
Nanowash mini-cyclones on an iron ore wet processing plant at Vallourec, Brazil.

Adam Holland

Adam Holland is CDE Global’s head of business development for mining.

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Thursday, 22 August, 2019 11:43pm
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