Process Equipment Update
are used to ensure pH is maintained at regulatory levels.” Originally, an air-operated diaphragm pump (AOD) was
considered for the task, but as wastewater from production contains around 33percent acid chloride, solids in the acid would destroy the pump’s membrane. The AOD would also be unable to ensure accurate dosing of both hydrochloric acid and caustic soda - and this would cause unwanted fluctuations in the pH levels. The company initially worked with a competitor supplier
of peristaltic pumps but switched to Watson-Marlow because of problems with long delivery times. The first Watson- Marlow baseplate pump was installed many years ago. Now, having reached the end of its natural life after many years’ reliable service, AHC had no hesitation in returning to Watson-Marlow to order another, this time in the form of a series 521F/REC close coupled pump, specifically designed for demanding industrial applications. Featuring high performance engineered plastics and a
stainless steel pumphead, easy set-up and maintenance are critical features of this innovative peristaltic pump, which is particularly suited to aggressive fluids. Its high resistance to chemical attack makes it rugged enough for the harshest environments, delivering cost-effective, precise pumping and a long service life (Fig.1). In peristaltic technology, nothing but the hose or
tube touches the fluid, eliminating the risk of the pump contaminating the fluid, or the fluid contaminating the pump. Fluids are drawn into the tube, trapped between two rollers, and expelled - the complete closure of the tube gives the pump its positive displacement action, preventing backflow and eliminating the need for check-valves. “We installed the 521F/REC pump fitted with Marprene
thermoplastic tubing elements in February 2010 and it has since performed extremely well,” says Heldens. “It’s pumping hydrochloric acid for about an hour a day - and caustic for around 15hours a day. The pump is linked integrally to our pH controller and I have to say we’ve had no issues whatsoever with reliability, it simply runs as required without any need for intervention, it ensures a high level of chemical resistance, is easy to operate and needs very little maintenance.”
Cost savings
Meanwhile supplier of pumps and accessories Verder Pumps South Africa (VPSA) says that the use of the VF125 pump range contributes to cost savings and increased productivity at platinum mines. This was seen at a precious-metal producer’s concentrator upgrade project, near Rustenburg, where VPSA was required to upgrade the thickener transfer pumps for higher production capacity, says VPSA consultant Daan Louw. The upgrade was possible as the pumps are able to pump slurry with 1.7 specific gravity and at a flow rate of 60m3
/h over a distance of 690m, with a height of 30m. The VF125 thickener pumps resulted in cost savings and
increased production capacity. Process engineering company DRA was appointed project
engineer on the project and approached VPSA to assist in the design of six thickener transfer pumps. “No other pump on the market is able to transfer the slurry without a second pump station, which would come at a significant cost to the
mine and would probably take more time to process,” says DRA project engineer Thys de Beer. There are currently 24 VF125 pumps operating at 37kWh
at the platinum processing plant. The design for these pumps included installing pulsation dampeners to help decrease the pressure build-up in the pipeline. Build-up in the hoses is eliminated by using rubber Verderflex hoses that are designed to increase life expectancy and production performance. These are designed to handle tough operating conditions; they reduce downtime, decrease maintenance costs and provide easy operation and reliable solutions in difficult pumping environments.
Sludge solution
Blackmer’s Abaque series of peristaltic pumps is said by the company to be the technology of choice when it comes to viscous and/or abrasive sludges, water-thin, non-lubricating fluids, corrosive chemicals, or sheer-sensitive materials. Because of the novel technology used, typical applications span many process applications, including wastewater, chemical processing and food manufacturing. The pumps are available in nine different sizes that
provide flow rates of .15-48,000l/h. Being constructed of natural rubber, Buna, or ethylene propylene diene monomer (EPDM) within the pump’s casing, they provide high levels of volumetric accuracy for sampling, transfer, and metering applications. A seal-less design eliminates leaks, contamination and wear problems associated with difficult to seal products, while they are self priming to nine metres. In market news, Pulsafeeder has announced the acquisition
of PeriFlo, a provider of peristaltic pumps for the industrial and municipal water and wastewater markets. PeriFlo offers a complete family of peristaltic hose pumps for a wide variety of applications. PeriFlo’s pump designs have been accepted by both the
international community and the US market since their introduction into those markets in the mid-1990s. Peristaltic pump technology is currently the fastest
growing technology in the positive displacement pump market; growing at almost twice the rate of the next closest technology, says the company. Meanwhile, Salem-Republic Rubbernow offers
replacement hose for all manufacturers of peristaltic hose pumps. Custom manufacture allows control over all properties of the hose, the interior core (tube), carcass (exterior shell) and supporting wall thickness. Because of this, Salem- Republic offers peristaltic pump hose completely customised to accommodate specific requirements for individual applications. Tube linings are available in the following material choices: natural rubber, EPDM, nitrile (Buna-N), or FDA safe white and tan gum. Peristaltic pump hose life is affected by three areas: the
pump conditions, quality of the hose and the material moving through the hose. The company’s ‘no-crush’ poly carcass is constructed using multiple plies of high tensile polyester cord. A smooth, precision ground concentric cover insures optimum performance and in-service life in the most demanding applications including pumping adhesives, starch, chemicals, pulp/papermaking slurries, lubricants, and food oils, waste and water treatment. l
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