Researchers discover a viable and more sustainable substitute to sand in order to reduce the environmental impacts of naturally occurring sand extraction.
Other than water, sand is the most exploited natural resource on the planet. However, sand extraction from seas, rivers, beaches, and quarries has a huge impact on the environment and surrounding communities.
In an attempt to remedy these issues, researchers from the University of Geneva (UNIGE) and the Sustainable Minerals Institute at the University of Queensland (UQ), Australia, have researched the potential of a viable and sustainable alternative to naturally occurring sand. This material, presented in a recent report published by the two universities, has been coined ‘ore-sand’.
Researchers have discovered that a step-change in mineral processing could drastically reduce mineral waste, while creating a sustainable source of sand. The ore-sand material has the potential to address two global sustainability challenges simultaneously, according to the report: ‘Ore-sand: A potential new solution to the mine tailings and global sand sustainability crises.’
The demand and negative effect of sand extraction
Sand has many applications, such as its use in concrete, asphalt, glass, and electronic chips. 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 approximately 50 billion tons of sand are utilised each year. Over the past two decades the demand for this material has tripled, primarily due to urbanisation and population growth, a trend which is expected to continue with aggregates use reaching beyond 50 Bt per year by 2030.
In addition to the risks of local shortages, the extraction of such a volume of sand has environmental and societal consequences. For instance, its extraction is causing in erosion in riverbanks, which significantly increases the risk of flooding. In some countries, sand mining has caused loss of livelihoods in communities.
Ore-sand advantages to solve sustainability challenges
As a resolution to these sustainability challenges, with the demand of sand continuing to increase, UNIGE and UQ scientists have forwarded their research to detect a viable and sustainable alternative to naturally occurring sand. This new source has been labelled ore-sand.
UNIGE’s Adjunct Professor at Department for Environmental and Aquatic Sciences of the Faculty of Science, Pascal Peduzzi said that: “Ore-sand has the largest potential in volume for reducing the amount of sand taken in the natural environment. By using what has been so far considered as ‘left over’ material, the project gives an important impetus towards a more circular economy.”
The production of ore-sand can help to reduce the production of mineral mining waste and thus the further build-up of mine tailings. Mineral wastes from the mining of ores currently represents the largest waste stream on the planet, estimated between 30-60 billion tonnes per year. These residues come from crushing operations to extract certain metals from the rock.
SMI’s Development Minerals Program Leader, Professor Daniel Franks believes ore-sand has the potential to address two global sustainability challenges simultaneously. “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,” explained Franks.
Reduction of carbon emissions
The 12-month study independently sampled and investigated sand that was produced from iron ore mining, pioneered by Vale S.A in Brazil, which has previously experienced tailings dam failures. After an analysis of the chemical properties and some refining operations, the researchers were able to demonstrate that part of the material stream, which would otherwise end up as mining residues, could be utilised as a substitute for construction and industrial sand.
“If these results can be replicated with other types of mineral ores there is potential for major reductions in global mine tailings,” added Franks.
“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”.
In addition, the life cycle assessment of ore-sand, based on the Vale case, indicates that substituting naturally sourced sand with ore-sand could potentially lead to net reductions in carbon emissions during sand production. The carbon emissions by transport however remains a key consideration.
A benefit for mining companies
“Considering the co-production of ore-sand is a significant advantage 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’,” explained Pascal Peduzzi.
“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 to convey the benefits of utilising this new substitute material are to collaborate with aggregate market players to demonstrate the material’s ease-of-use, performance and sourcing process.