Home > Pumping slurries: Is centrifugal or peristaltic the pumps for you?

Pumping slurries: Is centrifugal or peristaltic the pumps for you?

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The mining industry is known for innovation and the willingness to push technology to its limits.

Once it has made a decision on the right tool for the right job, it tends to stick with it. 

In slurry applications, centrifugal pumps have historically been the pump of choice, but is it the right choice?

There has been a noted shift in the industry towards peristaltic pumps, which provide the same service at lower operating costs.

In peristaltic technology, as opposed to centrifugal pumping, the fluid is only in contact with the hose and abrasive wear is fairly negligible.  

It works by drawing slurry into the SPX hose, trapping it between two shoes after which the slurry is expelled into the discharge line.

The complete course of the hose gives the pump its positive displacement action, offering 100% hydraulic accuracy, according to Watson-Marlow Bredel Pumps.

The pump company says that these peristaltic slurry pumps are designed to work in the tough conditions that are typically seen in the mining industry.

Mining for benefits
Fluid characteristics in the mining industry can be particularly dry with high solids content.

These conditions put a heavy strain on slurry pumps.

The ability of the peristaltic pumps to handle these extreme fluids, even up to 80% by weight, implies a huge reduction in the need for process water.

Typically four to six times less volume is processed versus centrifugal pump applications, which typically struggle transferring solids content higher than 30% by weight.

Therefore, facing nearly triple the limits of its pumping ability is likely to burn out the pump sooner rather than later.

When using centrifugal pumps, the slurries often need to be diluted with process water prior to transfer.

On top of this, the pumps consume additional water to flush seals.

Whereas peristaltic pump technology have no need for this excess water. 

Maintaining an advantage
As the mining industry pushes technology and equipment to its limits, continual maintenance is always needed.

But what advantages come of equipment if too much time is spent repairing and maintaining it?

Reduced maintenance is another advantage of the peristaltic hose pumps over their centrifugal counterparts, Bredel say.

If a blockage is to occur in a pipeline flow, as it is likely to in slurry pumping applications with high solids contents, the flow in a hose pump can be easily reversed to blow out the obstruction at the pump inlet. However, reversing the flow like this simply is not possible in a centrifugal pump.

As hose pumps have no seals, valve, diaphragms, stators, glands or other accessories to replace, it means that the pumps can be easily maintained in place without the need to remove and then transport the pump to a workshop.

Only the hose itself requires occasional replacement, which is a simple task that can be carried out in less than an hour. 
Other innovations built into the hose pumps include a leak zone, which has been created between the pump head bearings and the gearbox bearing, which provides protection as well as an early warning indicator in the unlikely event of a lubricant seal failure. Additionally, a transparent inspection window gives the operator easy access for set up and maintenance, halving the time it takes to carry out these jobs on similar pumps.

A solid issue
Ultimately, Bredel state that these peristaltic hose pumps provide contamination free metering and pumping, and have proven particularly successful in mining applications. 

The pumps provide performance rates of up to 80 cubic metres per hour and pressures of 16 bar.

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