Copper major Freeport-McMoRan says “the challenges of tomorrow” in mining demand innovation today, and no more so than in the waste management area where efficient water use will become central to land access in future.
“While our water use efficiency has averaged 88% over the last five years, we believe this will be challenging to maintain in the future using current processing and tailings technologies,” the company said in its latest annual sustainability report.
“As our long-lived, large-scale mines continue to mature and produce more tailings, the height and surface areas of our TSFs [tailings storage facilities] will increase, contributing to additional evaporation that we expect will increase our water consumption and reduce our water use efficiency.
“The specific ore type, processed at high rates, also drives consumption through entrainment.
“We believe that the most meaningful opportunities to improve our water consumption and corresponding water use efficiency over the long term will be driven by the deployment of new technologies and innovations pertaining to large-scale tailings management [that is, greater than 100,000 tonnes per day].”
Freeport, which produces about 9% of the world’s mined copper, said its operations last year generated 341 million tonnes of tailings, 408Mt of waste rock and overburden and 0.7Mt of slag.
Its total operational water use, including recycled and reused water (83% of the total used), was reported as more than 1.88 billion cubic metres. That compares with more than 1.71bcm, pre-COVID, in 2019.
“A significant portion of our current water consumption – the water that is lost in operational activities and cannot be recovered – is due to losses from evaporation and entrainment, or trapped water, at our TSFs,” Freeport said.
“Accordingly, we believe that the most significant improvement opportunities relate to our water consumption, and corresponding water use efficiency over the long-term will be driven by the deployment of new technologies and innovations pertaining to large-scale tailings management as well as the leaching of additional ore types rather than milling.
“In 2023, we created a dedicated Tailings Innovation Group with a focus on evaluating alternative tailings technologies for new TSF projects and supporting our operations teams to review existing TSF technologies.
“This group’s goal is to identify commercially viable technologies that may result in water savings, improved social and environmental aspects and/or enhanced geotechnical characteristics.”
Freeport said it was also actively involved in the GeoStable Tailings Consortium (GSTC), an industry-led initiative of 10 major mining companies focused on developing and implementing new technological applications for managing tailings.
“The GSTC plans to study options to combine various blends of tailings with waste rock to create geo-stable landforms that are expected to be stronger and more stable than conventional tailings deposition methods and likely to reduce process water consumption,” Freeport said.
