Quarrying & Mining Magazine
Innovation

Engineering the tail end of tailings

Adam Holland, head of Business Development for Mining, CDE, Ireland talks about his experience finding a foolproof solution for safe mining tailings dams.

Adam Holland, head of Business Development for Mining, CDE.

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.

And 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 their sheer existence, but there is still a long way to go in terms of the development of foolproof solutions. But, the more we understand about them, the more we can work towards eliminating the need for tailings dams.

This year we have been involved with ‘wet materials’ processing technology and waste management solutions that open 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.

The number of active tailings has been estimated at round 3500 in a variety of reports, but no up-to-date evidence-based data exists to allow 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 found. However, ‘piecemeal’ is not good enough in times of crisis and numerous tailings dams’ failures have resulted in unspeakable damage to the environment and to the lives of thousands.

Such dam collapses have been affecting mining operations indiscriminately throughout the world, from Russia to Brazil.

On a trip to Brazil back in August, on an iron ore tailings management assignment for a CDE client, I witnessed how the Samarco iron ore dam failure has reshaped the environmental legislation in Brazil, after its far-reaching consequences on the socio-economic and environmental make-up of the region.

CDE worked with Brazilian mining operator Vallourec on developing a dewatering system that rehabilitated a tailings dam by turning mining waste into revenue, or into materials for use in environmental rehabilitation.

This involved using six EvoWash washing units to dewater 30,000 tonnes per month of materials that were stockpiled as a dry product. Two banks of cyclones remove 30 percent of the mass (15,000 tonnes per month) to a filter press.

The resulting ‘cakes’ are used in soil composition and road brick manufacture. 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 these projects in Brazil the process is being replicated with needs-based variations across the world as an efficient means to manage tailings while adding value to mining operations. 

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