Instead of storing mine waste in complex and vulnerable tailings dams, mining companies in the Philippines can convert waste into valuable minerals, chemicals, and construction materials — mostly utilizing existing infrastructure — while making a profit, according to global professional services company GHD.
Speaking ahead of the 71st Annual National Mine Safety and Environment Conference (ANMSEC) in Baguio City on November 20, Paul Greaney, GHD’s Australian Market Leader for Resources, outlined how tailings repurposing offers both economic and environmental benefits for the Philippine mining sector.
GHD estimates there are 100 billion tons of mine waste produced globally each year. While some mines already use “reprocessing” to reclaim minerals from tailings, “repurposing” is an emerging practice of converting mine waste into construction materials such as geopolymers, aggregates, and engineered soils.
“If you extract the precious, critical, and strategic metals, as well as the chemicals that were used in the processing, you're basically left with a quarry. Now you can make low-cost, low-carbon concrete (including pre-cast), as well as soil for land reclamation and aggregates for road construction,” Greaney said.
“It also means that when a mine closes, there could be another 20 years’ worth of repurposing production to support the local economy and communities with jobs.”
Reducing the need to store waste in tailings dams is particularly important for the Philippines, with its high rainfall and seismic activity, as witnessed in recent earthquakes in Cebu and Mindanao. Tailings dam failures have cost lives and caused billions in damages globally.
Since 2000, there have been an average of five tailings dam failures per year worldwide, with most incidents not receiving media coverage.
In addition to the risks of failure, limited tailings capacity can also constrain production.
“It is a difficult decision for miners who must slow down production due to their tailings impoundment areas approaching capacity, especially given the current and projected prices for such commodities as copper and gold,” Greaney said. “Tailings repurposing deals with this secondary issue and may also mitigate the need to build new impoundments. Now you've got extra space to continue your production!”
“The ultimate goal would be having the repurposing systems installed at the same time a new mine is built, so you have virtually no tailings and no waste. And when it comes time to close the mine, the biggest liability is already gone,” Greaney added.
