Paul Cobbin of Hydroflux urges mining companies to make sludge disposal a forethought before it costs them big bucks.
Sludge is an unnegotiable part of the environment that could cost large mining companies a seven-figure cheque and catch out many others.
A small accommodation camp of 120 people may treat 40 cubic metres of sewage a day and transport 10 cubic metres of sludge a week out of the site to a registered discharge centre.
Paul Cobbin, Hydroflux Epco general manager, Epco products, estimates the sludge issue will cost the small camp $400,000 a year.
At a much larger site like Christmas Creek in the Pilbara, Western Australia, which has four to five sewage plants across the mining lease, the cost could easily multiply.
“The thing about sludge is the hidden cost of sewage treatment,” Cobbin says.
“It was costing that Christmas Creek mine millions of dollars a year just to move its sludge from the sewage plants to a registered discharge centre.”
But Hydroflux has conducted extensive research trials from 2012 to 2014 in nine different applications to study the performance, effects of polymer and washwater consumption.
The company, having developed an extensive knowledge in implementing the technology into the Australian market and conditions, proceeded to provide Christmas Creek with a technology called Huber RoS3Q inclined screw press.
This technology is fabricated from corrosion-resistant 304 or 316 stainless steel, and relies on an internal shaft screw that conveys the sludge through a triple-staged cylindrical wedge wire basket.
Christmas Creek was able to recover the cost of this installation within three months due to the amount of money the site was previously spending on sludge handling and transport.
“When it comes to sewage treatment, you’ve got two streams: effluent and sludge. What Huber QPress does is get that suspended solid (i.e. sludge) and take liquid out of it so it leaves behind a dry cake,” Cobbin tells Australian Mining.
“Previously liquid sludge was transported, but the new facility reduces offsite disposal volumes. We’ve taken 85 per cent of the volume, so we’re only having to transport the remaining 15 per cent.
“In terms of freight cost, you’d reduce that $400,000 to $60,000 a year. As you can see, the saving is quite considerable.”
The benefits don’t stop there. Hydroflux’s Huber QPress has a low energy demand due to its extremely slow-moving mechanism; that is, an internal screw speed of one revolution a minute (RPM).
Instead of relying on the mechanism of a high spinning drum, which is comparable to a plane engine, to push the water out of the sludge in the case of a conventional centrifuge, Huber QPress uses pressure to do this, requiring only 10 per cent of the power a centrifuge needs.
Further still, the sludge dewatering technology produces similar cake solids to high-speed centrifuges.
Wearing part is minimal, and cost of operation is considerably lower when using the Huber QPress, according to Cobbin.
“While you’re trying to remove as much suspended solid as possible in your sewage treatment, you can remove an average of 95 per cent of that using the Huber QPress,” he says.
The water discharge will have five per cent of particles remaining, falling conveniently within the guidelines of environmental discharge. The extracted effluent can then be used for dust suppression, toilet flushing and watering natural vegetation, effectively reducing the footprint of the mining operation.
Huber QPress can also be used during a fracking process and tunnelling. It comes fully enclosed with no pinch points, complying to workplace health and safety standards.
It is no wonder that over 1000 sites around the world, including more than 45 in Australia, use the German engineered and manufactured Huber QPress.