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Rockwood Pigments UK, a specialist in the manufacture and processing of colour pigments, has switched from progressive cavity pumps to the latest peristaltic technology from Watson-Marlow.

The new pumps have eliminated expensive repairs and downtime and they have also reduced labour and maintenance requirements.

Stoke-on-Trent-based Rockwood Pigments UK, part of the Rockwood Specialties Group, is a primary manufacturer of liquid, powder and granulated colour pigments used by manufacturers of coatings, plastics, rubber, paper, vinyl, concrete, cosmetics, ink and many other industrial products.

Until recently, the company used progressive cavity pumps for transferring cadmium sulphide slurry to its filter presses for dewatering.

In slurry form, cadmium is mildly abrasive – a factor that caused the repeated failure of seals and glands within the progressive cavity pumps.

Phil Tansley, operations manager at Rockwood Pigments, said: ‘The leaks caused by the cadmium pigment slurry were a constant source of disruption and cost to our manufacturing process.

‘Of course, the leaks also meant we were losing product, adding to our costs further, while cadmium is also toxic and is subject to strict health, safety and environmental controls in the workplace,’ he added.

Initially, the company tried switching to progressive cavity pumps featuring water flush to remove cadmium residues after each process.

However, this failed to significantly reduce the level of leaks and also introduced the need to drain water from the system.

Tansley had seen Watson-Marlow technology at the company’s headquarters in the US, where peristaltic pumps are used effectively for iron-oxide transfer duties.

He said: ‘In the US, the pumps run maintenance free, with the hoses replaced only once every four to five years.

‘This fact sold me on peristaltic technology and so I decided it might be worthwhile applying the pumps to cadmium-based duties here in the UK,’ added Tansley.

He purchased a single Bredel SPX65 high-pressure peristaltic hose pump from Watson-Marlow – a model that can displace up to 6.7 litres per revolution, with an operating speed of up to 50rev/min continuous or 90rev/min intermittent.

Peristaltic pumps have no seals, glands or valves and the fluid only contacts the bore of the hose or tube.

Tansley continued: ‘Obviously, the most important factor for us is that peristaltic pumps are liquid tight and have no seals.

‘The success of the initial Bredel SPX65 led to the acquisition of a further four identical models that have replaced our original progressive cavity pumps for transferring cadmium pigment slurry to the filter presses.

‘Since installation, we have eliminated leaks and witnessed a 10 per cent yield gain by product volume.

‘Furthermore, where we previously required an operator in almost constant attendance, we can now walk away and leave the pumps to run unmonitored,’ he added.

Other benefits include reduced maintenance and less burden on the company’s effluent plant as there are no residue slurries to wash away.

This is because the new system features an automated wash-water flush applied by the peristaltic pumps.

‘Press cake washing is a crucial step in our process as it removes all of the soluble or free cadmium left in the press cakes,’ said Tansley.

Watson-Marlow Fluid Technology Group

Watson-Marlow Fluid Technology Group (WMFTG) is the world leader in niche peristaltic and sinusoidal pumps and associated fluid path technologies. Founded on nearly 60 years of supplying engineering and process expertise and with over one million pumps installed worldwide, our pumps are tried, tested and proven to deliver.

WMFTG is a wholly owned subsidiary of Spirax-Sarco Engineering plc (LSE: SPX), a global organisation employing approximately 4,800 people worldwide. Watson-Marlow Fluid Technology Group comprises nine established brands, each with their own area of expertise, but together offering our customers an unrivalled breadth of solutions for their pumping applications:

  • Watson-Marlow Pumps: peristaltic tube pumps for biopharm and process industries
  • Watson-Marlow Tubing: precision tubing for pumping and other purposes, in a range of materials
  • Bredel: high flow, high-pressure hose pumps
  • Alitea: unique peristaltic solutions for OEM customers
  • Flexicon: aseptic filling and capping systems
  • MasoSine: gentle sinusoidal pumps for food, chemical and cosmetics applications
  • BioPure: advanced single-use tubing connector systems
  • Asepco: aseptic valves for the biopharmaceutical industry
  • FlowSmart: high purity sanitary gaskets, silicone transfer tubing and reinforced silicone hoses for the biopharmaceutical industry

Watson-Marlow Fluid Technology Group is an international operation based in Falmouth, Cornwall, UK. Watson-Marlow Fluid |Technology Group has offices in Argentina, Australia, Austria, Belgium, Brazil, Chile, China, Canada, Denmark, France, Germany, India, Italy, Japan, South Korea, Malaysia, Mexico, the Netherlands, New Zealand, Poland, Russia, Sharjah UAE, Singapore, South Africa, Sweden, Switzerland, Taiwan, USA and Vietnam.

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