THE design of pumps and dewatering systems are a major part of mining projects but often put on the backburner and overlooked because it can be quite a daunting task – but with the right team the process can be simplified.
Toolkwip marketing and product manager Jim Garrett said the company takes the stress away from dewatering projects.
“We don’t pretend we know it all, but the company has been doing this for more than 25 years,” Mr Garrett said.
“We work with each client to find the best pump to suit their requirements.”
One of the major aspects of choosing the right pump is water quality.
“It’s paramount because the water quality dictates the metallurgy that we use inside the pump,” Mr Garrett said.
“Pumps can be made from all different materials and alloys, from cast iron to ductile iron to white iron, to duplex stainless-steel, stainless-steel, and various polymers.
“We can even do internal coatings and plating depending on the severity of the water being pumped.”
Typically, across a lot of WA, the Hunter Valley and Queensland, there is a lot of saline water, and cast iron and saline water do not mix well.
“We look at different metals to get a longer lasting solution,” Mr Garrett said.
“We also look at the overall package, right from the foot valve, the bottom of the suction line, through to the outlet point.
“We look at all components right across the board and as a whole package before we specify the pump.”
Dewatering teams can rely on Toolkwip’s 25 years of experience.Avoiding pump failure
One of the most common causes for pump failure beyond corrosion is mechanical seal failure.
This could be due to cavitation, corrosion (chemical attack) or abrasion (grit and suspended solids in the solution being pumped) or even the pump running dry, which can lead to costly repairs and thousands of dollars per hour in downtime.
Mr Garrett said this is one of the reasons why Toolkwip works with a lot of Selwood dewatering pumps.
“The mechanical seal in these pumps is actually immersed in an oil bath, meaning it can run in SNORE operations – where it’s getting some water, some air, some water, some air,” he said.
In a traditional pump when it starts sucking air, the mechanical seal can fail very quickly, resulting in costly repairs and downtime.
“Whereas with the oil-filled seal chamber, the oil lubricates the seal while there’s no water there, which means you can get away with extended periods of dry running,” Mr Garrett said.
The centrifugal style pumps used are also fitted with a diaphragm priming system – which works on the air displacement principle.
“The diaphragm pump evacuates the air, sucks it out of the suction line and then when the water comes up into the pump volute, a ball float is pushed up and shuts off access to the air pump,” Mr Garrett said.
“Then the centrifugal pump takes over and pumps the water – and vice versa when the water level drops and the centrifugal pump is no longer pumping water, the float drops, and you’ve got full vacuum straight away.”
Mr Garrett said it’s a popular priming system because it is moisture tolerant and there is no potential oil mist expelled.
“It’s a more environmentally friendly option with no coalescing filters required and the absence of any possibility of oil mist being expelled,” he said.
The impact of pipe sizes
How far a liquid is pumped can directly impact the pump needed because friction losses come in to play.
“Often we see people running the pipeline before talking to the pump people,” Mr Garrett said.
“They might run something like a six-inch pipeline across two kilometres and when we turn up, we’ve got to use a higher head pump to get the same result as using a smaller pump on an eight- or 10-inch pipeline instead.”
Enormous gains in flow rates can often be gained with a smaller pump simply by increasing pipe diameter.
“I always advise people to look carefully at pipe size and consider the cost of upsizing your pipes and using a smaller pump,” Mr Garrett said.
“Not only will the pump cost you less, but your ongoing maintenance, diesel costs and electricity costs can be significantly lower.”
Mining operations also need to consider any solids or particles that might be in the water because this directly impacts the wear rate and metallurgy of the pump used.
“It’s also important to consider pump clearance tolerances,” Mr Garrett said.
“Some six-inch pumps will handle as little as 30mm of solids going through them, but with other pumps like the Selwood S150 (which is a true vortex style centrifugal), the six-inch pump will pass four-inch solids or 100mm of solids straight through.”
Mr Garrett said this is because, rather than the fluid going through the impeller, Selwood’s impeller is recessed into the back of the pump housing.
“That’s why it’s called a vortex, the centrifugal force passes the liquid through the pump in front of the impeller,” he said.
“It may use a bit more fuel than some other pumps, but you can very quickly make up the difference, saving a fortune on wear rates and associated breakdowns in the long run.”
Smart pump technology
The mining industry is becoming more and more automated and so too are pump systems.
Toolkwip fits 3G or 4G control panels on equipment so dewatering teams can remotely log in, turn the pump on or off, check its location with GPS and even check the pump speed.
“You can add all sorts of parameters, monitor pump performance, see if its running low on fuel – it doesn’t quite cook your lunch for you, but it does just about everything else,” Mr Garrett said.
“Automation has to be very carefully implemented and your systems have got to be set up to cope with it, but I like to think we’re leading the industry forward in that space by having these panels in there, combined with a pump that can run dry, because you can set it up so you don’t have to have someone standing by the pump.
“The expensive component of paid labour is removed, and the pump can still be monitored 24/7.”
Sustainability focus
Mr Garrett noted that Tier 4 emissions approved engines will only become more prevalent in future – particularly with Europe, UK and the USA already legislating for environmentally-conscious engine manufacture.
“We’ve already started building some models with engines approved to Tier 4 emissions and we’re also looking at high efficiency electric motors run by a generator,” he said.
“I think that’s going to change the dewatering scene in the coming years, as efficiency is going to be a key focus.
“Like it or lump it, whether the mine manger believes in climate change or not, as annoying as they may find it, the facts are that it’s going to be more widely enforced as time goes on – not less – so we’re going to have to start looking at how we can make these engines more compliant.”
More Information:
P: 03 8805 0500
W: www.toolkwippumps.com.au
