Using mining or quarry residues to counter the global shortage of sand

Over the past two decades demand for sand has tripled primarily due to urbanisation and population growth. Credit: UNIGE / UQ

Researchers from Switzerland and Australia have published a study on “ore-sand”

Sand is the second-most exploited natural resource on the planet, after water. A new study by researchers from the University of Geneva (UNIGE) and the University of Queensland’s Sustainable Minerals Institute (SMI) has found that a step-change in mineral processing could create a sustainable source of sand.

Concrete, asphalt, glass, electronic chips: sand has many applications. Composed of small mineral particles, this granular material comes from sensitive dynamic environments such as seas, beaches, lakes and rivers or, from static land-based environments such as ancient river deposits and rock quarries. It is estimated that 50 billion tons of sand are used each year. Over the past two decades demand has tripled primarily due to urbanisation and population growth and the trend is expected to continue.

Researchers from the University of Geneva (UNIGE) and from the Sustainable Minerals Institute at the University of Queensland (UQ), Australia, have researched the potential of an alternative to naturally occurring sand. This material, presented in a recent report published by the two universities, has been coined ‘‘ore-sand’’.

As part of a 12-month study, samples of mining waste from ore extraction were taken and analyzed. The company involved was Vale S.A. in Brazil. After an analysis of the chemical properties and some refining operations, the researchers were able to demonstrate that the part of the material stream which would otherwise end up as mining residues could be used as a substitute for construction and industrial sand, in the same way as recycled concrete and steel slag.

“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 50 km range. This could contribute to at least 10% reduction in the volume of tailings generation at each site. Simultaneously, almost half of the global sand market (by volume) could find a local source of ore-sand. For example, ore-sand could potentially substitute 1 billion metric tons of sand demand in China,” explains Professor Daniel Franks, Leader of SMI’s Development Minerals Program of Queensland University.

In addition, the life cycle assessment of ore-sand, based on the Vale case, shows that substituting naturally sourced sand with ore-sand could potentially lead to net reductions in carbon emissions during sand production.

Yet, emissions from transportation are an important aspect to consider.

“Considering the co-production of ore-sand could bring a significant benefit for mining companies: it reduces the large tailings which hinder operational mining activities, while at the same time can generate additional revenues. Ore-sand is a step towards a ‘no tailings mine‘, explains Pascal Peduzzi from the University of Geneva. “Developing countries have fewer options for using recycled aggregate materials, given their more recent infrastructure. However, many have mining operations that can generate ore-sand as a by-product.”

Some of the next steps will be to collaborate with aggregate market players to demonstrate this substitute material’s ease-of-use, performance and sourcing process.

Ore-sand: A potential new solution to the mine tailings and global sand sustainability crises

Source: University of Geneva (UNIGE)

(07.06.2022, USA: 06.07.2022)