What is biocementation and how does it work on mine roads?
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New technologies, rooted in natural biological processes have emerged. One of these soil stabilising products allows mine operations to tackle two significant challenges: conserving scarce water resources and improving the quality of haul roads. It’s a method that is both effective and sustainable.
This new category — biological dust control — uses a natural biocementation process to bind dust particles together into a solid wearing course layer. It uses 90 percent less water than spraying water alone, and gives bitumen emulsion a run for its money when it comes to stability, with none of the environmental downsides. In this article, we look at what it is and why this alternative to traditional dust suppression methods is sparking interest across the sector.
How does biocementation work?
“The basic technology behind biocementation is naturally occurring bacteria that devour the nutrients in soil and convert it to a mineral,” says Luitpold Fried, Chief Technology Officer of Bind-X.
“That mineral becomes a glue that binds soil particles together. You end up with solidified soil, which you’ll see in natural structures like the Pinnacles of Nambung National Park or the Thrombolites at Lake Clifton in Western Australia.”
Indeed, there is a strong West Australian connection to the technology, originally developed at Murdoch University. What Bind-X has done is further developed this research and this natural process to make it suitable for mines wanting to move away from environmentally unfriendly dust control methods.
“Normally, bacteria like to live in liquid. We were the first to be able to dry this biocementation bacteria and keep them alive so we can deliver our product as a powder,” explains Luitpold.
This powder base contains only a small amount of bacteria, but when mixed up on-site, they quickly come back to life and get to work.
“It’s like if you make pizza at home, you go to the grocery store and you buy the dried yeast, which you add to your dough. The client gets a big bag with our product in, they dissolve it in water, and the process gets started.”
How is it applied?
Biological dust control can be applied in two different methods — one is to grade the existing road, spray Terrabind into the loosened material, then mix and compact the road surface to build a stabilised 10-15 cm layer (build-in application), while the other is to spray it onto the surface of existing roads (spray-on) and create a stable crust on the top wearing course. Both methods use equipment you already have onsite.
“At the moment, 70 percent of our clients use a spray on application,” Luitpold says. “Bigger mines might also build the road from scratch, especially if it’s a heavy use road like those in Australia, where you’re getting trucks with loads of 500 to 800 tonnes.”
Luitpold says switching to biocementation is often a case of just switching to a new product, rather than a new process. Given the importance of stable roads for productivity, it’s important that biological dust control can match or exceed bitumen emulsion’s performance while being more sustainable.
“The performance is identical to bitumen emulsion, so you get high flexibility and very similar levels of stability.”
The surface created by the biocementation process is solid and flexible. It’s a good match for bitumen emulsion in terms of road durability, without any of the toxic, crude oil-based downsides. Those drawbacks — sticking to equipment, damaging water trucks, and the toxicity to people and the environment — are familiar to operations teams who maintain haul roads. By creating a smooth, low-friction layer it reduces damage to tyres and vehicles, reducing maintenance and enabling safer, faster cycle times.
Where is it being used?
Luitpold says that mines in more than 15 countries, including Australia, have adopted biological dust control for environmental, safety and productivity reasons.
It’s been adopted quickly across the mining sector because it’s reapplied far less often than plain water for dust control, with each new application strengthening the original surface by binding any cracks together. This matters in parts of the world where water is a scarce and increasingly expensive resource.
“We had a client in Senegal who had to spray water five to 10 times a day to keep the dust down,” Luitpold says.
“They were consuming a lot of water and spent too much time and money on the maintenance of the trucks, which were on the road all day.”
Overwatering of mine roads also causes erosion and destabilisation and tends to make the surface muddy and slippery. This makes the roads less safe and requires trucks to slow down and maintain larger braking distances. All of which has a big impact on cycle speeds and productivity.
Within three months of switching to biological dust control, the mine saw a dramatic drop in water usage and haulage costs. Water use was reduced by 85 %, diesel consumption also dropped by 85 % and CO₂ emissions linked to dust control were slashed by 94 %.
“Water is a scarce resource in Senegal, so they have to drill really deep to get the groundwater for their operations,” Luitpold says.
“Cutting back on water has a real benefit for them. And there are local communities close to the mine — farms and schools and families of mine employees — so it’s important that the site uses a dust control method that is natural, biodegradable and non-toxic for people, animals and water sources.”
Similarly strong results have been seen in other parts of the world, with Australian iron ore mines adopting the technology over the last few years. Indeed, the increasing scarcity of water and tightening environmental regulations in these arid regions will make plain water and older dust control methods like bitumen less and less attractive over the coming years.
Future-proofing your haul roads
There is another major change that will require mining operations to think again about the most effective means of dust control.
“If you have 250 kilometres of road networks and you’re running autonomous trucks, without a person at the wheel, then dust control is going to be really, really important to you,” Luitpold says.
“A person at the wheel will drive slowly through heavy dust, but an AI-driven truck will just stop dead.”
As times change, it makes sense to look at what else is out there if you don’t want to be left behind. Biocementation is a proven method of dust control that’s economical, simple to apply and makes your roads better. With zero environmental risks and much less water required, it’s an appealing option for operational and environmental teams.