What do you get when you cross a nuclear physicist, a chemical biologist, and an engineer? An innovative, cost-effective, and environmentally friendly solution to one of our industry’s biggest problems. And that ain’t no joke!
Recently @ The Coalface had the pleasure of catching up with the Directors of Mine Water Solutions, Kevin Murphy, Michael Higgins and Tom Perkins.
Kevin, who has a background in chemical biology, and Michael, who is an engineer, have been working with key partners such as eminent nuclear physicist Bruno Angelico and eminent microbiologist David Lark. The collaboration has brought together some impressive credentials across a wide range of fields.
“I guess you could say we are a bunch of old scientist blokes who like solving problems,” Kevin said with a grin. “Well except for Tom, he’s our young gun Operations Manager and the one who keeps us on track.”
Solving problems is certainly what they have done with the development of a new way of treating mine wastewater. Also known as tailings, mine wastewater usually consists of a slurry of ground rock, water, debris, plus whatever chemical reagents remain after processing. The composition of tailings varies at every mine site and is usually stored in tailing dams or ponds.
Efficient, cost effective and sustainable tailings treatment is a major environmental challenge, not only for the approximate 350 mines in operation in Australia, but for the estimated 25,000 abandoned mines around the country that require water remediation.
If not managed properly, tailings can have chronic adverse impacts on the environment and safety, with pollution from effluent and dust emissions being potentially toxic to humans, animals and plants.
So yes, it’s a big problem. That’s where Mine Water Solutions come in.
Funnily enough, it wasn’t a problem that they were looking to solve, rather it came about when one day a coal miner asked Kevin what he knew about wastewater treatment.
“I asked him why he wanted to know, and he replied they were having difficulty managing their tailings. He told me the water on site was so toxic that if you popped a frog in the water, it would be dead after a few strokes across the surface,” shared Kevin.
“My curiosity was instantly spiked. I asked him to give me a sample of the water and after some preliminary analysis we sent it to our NATA laboratory for a full in-depth analysis. It turned out the pH in the water was 2.1 which is very unusual to have that level of acidity in nature. That’s when I learnt that every mine in Australia has the same problem with their wastewater and there’s even a name for it, mine acid water or acid mine drainage.
“We started working straight away on experiments to see if we could find a method to neutralise it and we came up with a solution, Catalyst 365. We named it that because it works 365 days of the year.”
Currently, there are two main methodologies for dealing with tailings. One is reverse osmosis which involves using a high-pressure pump to force water through a semi-permeable membrane. The water is then sent to a large storage tank where it is held for use. The second is evaporation. In its simplest form, the evaporator sprays the untreated water into the atmosphere which gets carried away with the wind and converts the water portion to water vapor. Both are extremely costly and come with environmental risks.
What Kevin and his team have developed is a catalyst solution that is an alkaline hydrolysis redox process that instantaneously oxidises, reduces, and causes precipitation of suspended particulates while adjusting the pH to the desired levels. Leaving the treated water suitable for agricultural application or utility water around the mine site.
“We are using a well-known process, but we have adapted the principle to suit acid mine water. Our laboratory analyses a sample of the content of the pit water, as each mine will have a different composition, allowing custom solutions for each mine,” said Kevin.
“It’s an incredibly simple application, there’s no up-front costs or special machinery needed. All you need is a pump. The solution is injected into the suction side and it’s mixed as it goes through the pump and discharged into a settling pond, which doesn’t even need to be lined. The reaction is instantaneous. Suspended metals and particulate matter are oxidised and precipitated, leaving the crystal clear water separated from the concentrated mineral dense pit water. The precipitated residue can be used to recover any valuable minerals which were in suspension in the pit water.
“Compared to traditional methods, our solution is much more cost effective. It costs about 56c per litre for evaporation. Reverse osmosis works out at 44c per litre. Our solution, 7c per litre. No matter what type of wastewater you have.”
Water on mine sites is a valuable resource and their solution allows wastewater to be converted into a usable resource suitable for all types of applications on site, such as dust suppression and irrigation. Kevin also explains that they can elevate the levels of the pH so it can be used in coal wash plants and for other mining applications without having to use slaked lime.
Another great benefit is the treated water is suitable for agriculture and mine remediation. In fact, it even acts as a natural accelerator for seed germination.
So once the water has been utilised, what do you do with the benign precipitate sludge that’s left over? It can be discarded as waste material or reprocessed for mineral recovery. Depending on the mine, you might even be looking at rare earth minerals if in fact they are present in the tailings. Kevin explained that at one abandoned copper mine that they had recently sampled, there was around $29 million in recoverable minerals in suspension in the pit water, just sitting there waiting to be recovered.
During the interview, Kevin demonstrated how the solution worked using a water sample from the same copper mine. It’s one of those things that is hard to believe until you see it for yourself. But once you’ve seen a couple of fish happily swimming around in the water that was once considered toxic, it’s hard not to get excited about what they’ve developed.
The economic benefits are clear, but what the team are most passionate about is the environmental benefits. Mine water is an environmental hazard, and their solution will allow it to be safely discharged back into ecosystems.
It’s great to be able to share a story on a new development that has the potential to change the mining industry for the better, not just in Australia, but all over the world. Globally, it’s estimated there are more than a million abandoned mines worldwide and a significant number of them will need water remediation. Thanks to the team at Mine Water Solutions there is now an easy and effective way to treat them.
