Investing in water recycling tailings management, FLSmidth is in the midst of a co-development project demonstrating how dry stacked tailings work for large tonnage mines. The collaboration is ground-breaking for how the industry tackles tailings management at large mines going forward. The process, called EcoTails®, is a colossal filter press enabling recirculation of 90-95% of process water. It blends filtered tailings with waste rock creating GeoWaste™, a geotechnically stable product.
“Dry stacked tailings technology is not new to the mining industry, but has traditionally been used for smaller tonnage mines which typically are less than 15,000 tons per day,” says Todd Wisdom, Director of Process Line Tailings Systems in FLSmidth.
FLSmidth is working hard to innovate and make that small mine technology applicable for much larger mines. As regulators and mine owners become aware of these new alternatives, and as they are proven technologically feasible, filtered tailings will become a potential solution for all mine tailings.
Applying this technology at large scale mines will have an impact on mines’ total cost of ownership. Systems that reduce costs of tailings processing through minimising water use, while eliminating the risk of tailing dam breaches, are advantages both for miners and to the local communities. The potential benefits from EcoTails are numerous; including improved cash flow through faster mine closure, lower water costs and easier permission approval.
The initial costs are competitive, with EcoTails economically compariable to traditional tailings solutions in CAPEX and OPEX over the life of a mine. “For a mine with a 1 billion tonne reserve, they will be looking at $500 million in capital cost and $2 billion in operating expenses. EcoTails is competitive on a total cost basis – with less risk and more water recovered, and that should be interesting for the industry at large,” says Wisdom.
There are also possible large savings in switching from a traditional cyclone sand dam to a filtered tailings solution, as the amount of make-up water can be slashed fourfold. This means water savings of 53,000 m3 per day for a 100,000 tpd operation. “At a water cost of $5/m3 – as is the cost in several arid locations in South America – that is $1 billion over 10 years saved in water expenses alone,” adds Wisdom.
Reduced water usage also means a decreased environmental impact – just one benefit that can help save time and money on permissions for a mine. This tailings storage solution reduces environmental impact and water demand, and significantly decreases the footprint especially in comparison to a conventional tailings storage facility. The high-density, geotechnically stable GeoWaste is safe for dry stacking, even in areas of high seismic activity. That adds up to a solution that also eases the criteria for obtaining a license to operate and accelerates permits processing.
Mines have to factor in closure costs, which mean properly reclaiming land when the mine winds down and ceases operation. Bonds typically cover these costs, and are collected by the mining operation once the mine is properly closed. With the EcoTails filter stack, progressive closure is possible and the bond money reclamation can start sooner – even before the mine reaches the end of its life span – thereby providing a positive cash flow.