A new solution to the problem of dwindling sand

Researchers are working with the mining industry to create a new source of sand – which at present is being mined at an unsustainable rate and might run out with a generation.

Miners are being asked to extract sand from their ore processing, to help alleviate the global sand crisis. Researchers are calling for a paradigm shift, they call ‘nose to tail mining’, to extract sand by-products during mineral processing, but before it becomes waste.

The first major metal mine in the world to receive environmental and production licenses to make this byproduct is Vale’s Brucutu iron-ore mine in Minas Gerais, Brazil, which produces more than 1 million tonnes of sand for road sub-base, brick and concrete making, writes Prof Daniel Franks of the University of Queensland in a commentary in “One Earth,” published by Cell Press.

A similar sand project with Newmont mining, a copper-gold mine, in New South Wales, is looking technically feasible.

The size of the problem

Imagine building a concrete wall, 35m high and 35 m wide, around the equator. That’s about what we use in aggregates each year, making it the third most exploited commodity — after air and water — on the planet.

Sand is nothing more than little chunks of rock, just the right size and shape to make all the roads, buildings, wine glasses and almost everything else we need. We mine a staggering 12.5 million Olympic swimming pools -worth annually, writes Franks, in a new paper exploring the problem and the solution.

At this rate  the world may run out of construction-grade sand by 2050. The UN considers sand extraction a crisis.

As demand exceeds supply, the industry is resorting to crushing stone.

The answer could be in the mines

To reduce our global sand extraction, Franks and his collaborators — a national and international team of researchers — are arguing for a paradigm shift in the mining industry.

Right now, much of mining’s diggings go to waste. Around 12.7 billion tonnes of tailings are produced each year, with more than 280 billion tonnes stored in facilities around the world.

The researchers propose that the mining industry include aggregate production in established ore extraction processing. The industry could, Franks writes, “add mineral processing circuits to extract a clean byproduct or co-product of (mostly) metal-ore mining”.  

They refer to it as ‘ore-sand’ to distinguish it from a process that recycles waste. “Nose-to-tail mining” should be regarded as a waste prevention and reduction strategy—not a waste reuse or repurposing strategy, says Franks.  Metal mines could also become licenced quarries.

Sand extraction reduces toxic tailings

But tailings have long been viewed with suspicion, particularly given the impacts of toxic mineral leachate on environmental and human health.

Most of these toxic elements are associated with sulphide minerals, says Franks. Those sulphides are removed when ore-sand is processed, and because the construction industry prefers coarse sand, those remaining are more likely to be trapped within the larger particles. 

Because the mining industry is already crushing and grinding the rock, those in construction don’t have to process it before use,, saving on energy and on carbon emissions. 

Of the tailings waste that remains, he says, “you have a much smaller amount of tails to manage, therefore you can manage them in more efficient ways.” 

Using more of the ore

Franks believes that the main challenge will not be technical, but in “developing the innovation ecosystem and collaborations necessary for the mainstream construction materials market to adopt a new product.”

It’s a: “…a reimagination that brings us closer to using every part of an ore body, from nose to tail.”

The costs of sand mining