Total elimination

Tailings present a challenging economic opportunity 

Australia needs a new approach to tailings. 

The growing interest in clean energy technologies will potentially drive a four-fold increase in demand of associated mineral resources by 2040, according to the IEA. 

Not only are these mineral resources scattered across the globe, but the pathway to extracting them is not always entirely economical, with some critical minerals being found in very low concentrations or as byproducts of other metal extractions. 

With low-grades and byproducts comes an increase in tailings, introducing risks and constraints in meeting growing mineral demands.  

The challenge, and potential new opportunities, present in tailings cannot be overlooked.  

Between the years 1915 and 2021, there have been 366 documented cases of tailings dam failures in 46 countries, resulting in the loss of 3043 lives, according to a 2024 study titled Mine tailings dams’ failures: serious environmental impacts, remote solutions. 

One 2012 study found that 14bt of tailings were produced by the mining industry in 2010, with that number likely to grow. Experts now forecast a dramatic increase in mining waste production through to 2050, due to lower ore grades processed with conventional approaches.  

How do we address waste, treat it and ultimately eliminate?tailings while making the most of low-grades and byproducts? 

The Australian Mining Review speaks with Clareo Australia director Grant Caffery and managing director Satish Rao on the latest developments in?tailings?innovation from their Reimagining Tailings white paper. 

Reimagining Tailings presents a roadmap for mining companies that want to start the journey to zero waste and tailing optimisation. 

“People have always seen tailings as the problem child at the end,” Mr Caffery says. 

“It’s seen as waste or something that just costs money.  

“If we start to think of tailings as an end-to-end system — for example, how do we combine improved tailings with water recovery, with improved operations of generating cash through the concentrator — then we end up in a better spot.” 

Mr Caffery and Rao argue there is no silver bullet to eliminate waste and?tailings, with challenges varying by commodity, deposit, geography and operating legacy.  

“As new mines are built, they will be built the conventional way until there’s enough of a roadmap of derisking and advancement so that operators get the confidence that they will be able to deploy new technologies successfully,” Mr Rao says. 

“That’s the roadmap and the journey that needs to happen for any new mines and developments.” 

Mr Caffery and Rao have proposed a continuum of approaches to address?tailings?that can form the basis for a technology and innovation roadmap for a mining company that wishes to embark on a zero waste and?tailings?optimisation journey. 

Optimise recovery

Miners must first look at optimising recovery so that all potential value is recovered from waste and tailings, including minerals and water. This can also improve safety through dewatering and dry stacking. 

This can be achieved through the repurposing of tailings, reprocessing of tailings, dewatering of tailings and additional treatment of water and acid mine drainage. 

Chemical and physical alterations can be applied to remove contaminants or make them mor suitable for secondary uses, such as in building materials. 

Chemical processing innovations can be used to recover valuable metals, salts or acids that may otherwise be left behind in tailings.  

The advancement of physical mechanisms, such as conventional filtration and dewatering rolls, or the use of chemical additives could make it easier to target and remove solids and enable complete dewatering. 

Combining these approaches will allow for a closed loop and circular solution for water within mine operations. 

Mr Caffery says being able to close the water balance and reduce the demand on water is very important.  

“For example, coarse particle flotation is better from an energy perspective, so you get double the benefits just from course particle flotation,” he said. 

“Looking at operations from a holistic perspective, if you can solve and improve your combination to get better separation, then you get better recovery, lower energy, lower water use and better tailings.  

“In the industry, I still see that there are tailings people, dewatering people and concentrator people. Those touch each other, but they’re not the same thing. We need to get to the point where they’re the same thing.” 

Eliminate waste

Miners must look to reject waste as early as possible in the process. 

The requirement of fewer processing inputs and lower generation of waste are just some of the benefits this approach could unlock. 

This can be achieved through precision mining, bulk ore sorting and ore upgrading and reducing or eliminating water in processing through dry processing. 

Precision mining through advancements such as directional drilling and keyhole mining show promise in the oil and gas sector, potentially reducing the waste that is brough to the surface for processing. 

Other advancements, such as bulk ore sorting and ore upgrading, can enable early waste rejection and improve efficiency. 

Dry processing, which could be used for some commodities such as iron ore and rare earths, can eliminate or minimise the use of water, significantly lowering tailings production. These technologies include dry crushing and grinding, dry separation and dry flotation.  

Mr Caffery says that every time the ore is touched, some sort of upgrading should occur.  

“Whether that’s putting drill holes in when you’re actually doing blast holes, getting knowledge about what’s in the ore so you can actually design a blast better to separate ore and waste, all the way through to when you’re actually excavating and putting the material onto the truck,” he said. 

“You’re gradually upgrading the ore when you have large particles, so you’re essentially rejecting tailings before they can become tailings.  

“Then you can upgrade the grade of the material and even the type of material that’s going into the concentrator so that A, less tailings are produced and B, those tailings are potentially better for becoming tailings as well.  

“It’s all about sensing and making decisions right from day one so that you end up with the best grade and the best material feeding the concentrator, both from a product perspective and also from a tailings perspective.” 

Process everything

Miners can derive value from the entire rock that has been extracted and process all of it. 

This can be achieved through several emerging technologies such as molten oxide electrolysis, use of alternative solvents and bioleaching. 

Some technologies include molten oxide electrolysis, which uses renewable electricity to convert all ore grades to high quality liquid metal in a one step process.  

Bioleaching is another option that employs microorganisms to leach specific minerals from low grade ores and selectively target metals like copper, gold and nickel. 

Mr Caffery says mindset of miners and technology are the biggest hurdles. 

“If you want to process everything, we’re nowhere near that,” he said. 

The white paper highlights that certain commodities and minerals can be more readily targeted, presenting starting points for mining companies.  

Valuable minerals such as scandium, tellurium, rare earths, molybdenum and sulfur are often left behind in copper tailings, as current technologies cannot selectively target trace elements in low concentrations. These minerals may represent future processing opportunities. 

As we consider a potential future without tailings, or at least without tailings as we know them, we may continue to look further beyond these options.  

Mr Rao says the mining industry could take inspiration from an industry with even more limitations. 

“This is an area where you could actually have transfer of both the mindset and technology from another industry,” he said. 

“The space industry is used to working with a lot of constraints while making huge advancements relatively fast. 

“Mining could borrow from the mindset and then also the technology itself when trying to extract everything they can from a resource.  

“That’s worth experimenting and improving on earth.” 

Transform leaching

Improving the cycle time and recoveries from leaching can help make it a viable alternative, with reduced waste and ability to target lower ore grades. 

One solution is heap leaching, which is widely used for commodities like copper. Heap leaching is preferred thanks to its relatively lower cost in treating low-grade ores.  

A range of innovations from novel oxidants, lixiviants, to other chemical and biological approaches are attempting to transform leaching as we know it. 

“To me, leaching is the critical piece of the puzzle that’s still missing and is needed, from a copper perspective,” Mr Caffery said. 

“Copper is the biggest issue. A, we need more of it, B, it produces a lot of tailings.” 

“To me, the holy grail is chalcopyrite leaching. 

“There is an increased focus in the last 5-10 years on unlocking that because grades are declining continuously. 

“What used to be considered waste is now almost a good grade. 

“We need to push towards a leaching technology so we can start to heap leach these large low-grade chalcopyrite resources.” 

Mr Rao says that in the past, leaching was largely neglected and remained a fairly simplistic approach, despite very complex reactions taking place within the heap.  

“People are now trying to really understand what’s going on inside the heap,” he said. 

“There’s a lot that goes into understanding the dynamics that are happening inside. People are introducing advanced monitoring of the heat, using tomography to identify the needy, dry spots, to determine if the raffinate and lixiviants are flowing well. Those are all going to be important and overall system design characteristics will play a big role.” 

Recovery through in-situ extraction

Miners should look to develop new approaches to extracting valuable minerals directly from the ore body. This will mean that waste and mine tailing produced from conventional mining and processing won’t be produced. 

This can be achieved through modifications to the ore body involving such as the drilling of wells that inject a leaching solution into the mineral deposit. 

Not only are there technological challenges to in-situ extraction — including ore body characterisation, permeability enhancement, effective lixiviants, solution flow and effective monitoring and control systems — there are also considerable regulatory barriers. The current regulatory landscape does not provide specific guidelines for in-situ extraction, further complicating the process of obtaining operational permits. 

Mr Caffery says there is a regulatory skeleton, but we need much more. 

“Miners have to bring communities along for the ride as well.  

“It’s up to miners, communities and government to all work together to build out what the regulations look like and different jurisdictions will move at different paces.” 

Mr Rao says it’s not just the regulatory aspects that are concerning; it’s also societal and community aspects.  

“Ensuring that the community is an important part of the discussion is critical, otherwise, they will push back and if there’s no clarity around this, the regulators will respond to that,” he said. 

“The regulatory landscape is different across regions, countries and local jurisdictions, making it challenging for mining companies.”