Researchers from Queensland and Geneva have used samples from one of Vale’s largest iron ore sites to repurpose mineral waste while alleviating the global sand crisis.
The team explored whether “ore-sand” from iron ore can provide a suitable alternative to natural sand, in a report titled: Ore-sand: A potential new solution to the mine tailings and global sand sustainability crises.
Sand has many applications such as concrete, asphalt, glass and electronic chips. As such, more than 45 billion tonnes is used each year and demand has tripled over the past two decades leading to a significant global shortage.
Simultaneously, the mining industry is constantly considering better ways to manage the issue of mine waste, or tailings, which led the teams from the University of Geneva (UNIGE) and from the Sustainable Minerals Institute at The University of Queensland (UQ) to coin the term “ore-sand.”
“The production of ore-sand can help reduce the production of mineral mining waste and thus the further build-up of mine tailings,” said UNIGE professor and report author Pascal Peduzzi.
“Mineral wastes from the mining of ores currently represents the largest waste stream on the planet, amounting to between 30–60 billion tons (27–54 tonnes) per year. These residues come from crushing operations to extract certain metals from the rock.”
The researchers conducted a 12-month study on sand produced from iron ore mining at Vale’s Brucutu mine in the Brazilian state of Gerais.
This was Vale’s first mine with full-scale sand recovery operations and an environmental license for sand production.
“Separating and repurposing these sand-like materials before they are added to the waste stream would not only significantly reduce the volume of waste being generated but could also create a responsible source of sand,” said UQ professor Daniel Franks.
The study found that part of the mine’s mineral waste stream was suitable for construction and industrial sand and Brucutu was hardly unique in such qualities.
“If these results can be replicated with other types of mineral ores there is potential for major reductions in global mine tailings,” Franks said.
“By mapping mining locations worldwide and modelling global sand consumption, we discovered that almost a third of mine sites can find at least some demand for ore-sand within a 50km range.
“This could contribute to at least 10 per cent reduction in the volume of tailings generation at each site.”
The research also found almost half of the global sand market could find locally sourced ore-sand.
“For example, ore-sand could potentially substitute 1 billion metric tons (907 million tonnes) of sand demand in China,” Franks said.
The next steps for the researchers will be to present the findings to major aggregates producers – in Australia: Boral, Holcim, Hanson and Adbri – to prove the ore-sand’s worth in construction materials.