Why do mines need progressive cavity pumps? African Mining Briefs looks for answers.
The mining industry uses a wide array of pumps, so where do progressive cavity pumps fit, in a sector awash with scores of products that, ostensibly, have little differentiation?
At the outset, by looking at characteristics of progressive cavity pumps, it would be easier to understand their niche in mining. If you google “progressive cavity pumps”, in a flash, many websites of hundreds of thousands of suppliers dealing in products coming in different shapes and sizes would pop up. But despite the differences, there would be features fundamentally common in all progressive cavity pumps, which determine their applications.
The Star Pump Alliance is an association of several well-known medium-sized pump manufacturers, which are active worldwide. On its portal rich with information about pumps for end-users, in one of the articles, it provides a vivid definition of Progressive
Cavity Pumps: Progressing cavity pumps belong to the group of rotating positive displacement pumps. They are self-priming, valve-less, and due to their high process liability and suction capacity. They are often used for the continuous, gentle conveyance and precise dosing – in proportion to speed – of difficult media. This provides a clear understanding of their nature.
Based on what can be gathered from various pump OEMs, the following are the features of pumps that stand out: Flow proportional to speed, valve-less operation and flow control, minimal pulsation, self-priming, no-day to day maintenance required, versatility (can be installed horizontally or vertically and in virtually every position), handles multiphase products (both liquid and gas).
In general, progressive cavity pumps can handle media with the following features, fluids with or without solid contents (Max. solid size up to 150 mm, low to high viscosity
(1mPas to 3 millions mPas), Thixitropic and dilatant, shear sensitive, abrasive, nonlubricating and lubricating, aggresive (pH 0 -14), adhesive and toxic.
Out of these features, Start Pump Alliance stresses ruggedness and ease of maintenance as the most relevant in mining conditions. “In the rough surrounding of mines and processing plants and with the variety of aggressive and abrasive media that need to be pumped not only the performance but also the ruggedness and the ease of maintenance are essential pump properties.” Expanding more on this point, Steven Rose from Dernoco says that progressive cavity pumps have a less maintenance burden than centrifugal pumps.
“Traditionally, a large, single, multi-stage pump has been used with tappings removed from various points to supply water at increasing pressure to match the requirements of the slurrypump. These multi-stage pumps are both expensive to purchase and require high levels of maintenance owing to the abrasive nature of the mine water that is typically used in gland service application,” he comments.
What are they suitable for?
Due to this factor, it is now understandable why progressive cavity pumps are ‘the weapon of choice’ in broad range of applications in various mineral types.
Common applications for PCPs in mining include but are certainly no confined to the following: transfer of minerals slurries, void back-filling, dosing of explosives, thickenersunderflow applications, Centrifuge filling, chemical dosing, Water treatment, Cake transfer, Leachate treatment, Gland water supply and Sludge feed to dewatering machines.
Manufacturers of mining equipment and chemicals use progressive cavity pumps for the following applications: decanters and centrifuges, tunnel drilling equipment, flocculants, chemicals dosing and liquid explosives.
Which mine types?
Due to their versatility, there is a good reason why progressive cavity pumps are common on mine sites throughout Africa. One is likely to find the pumps in the following mine types: coal, copper, gold, iron ore, tin, uranium, etc.
The foregoing facts settle the question on why progressive cavity pumps have a wide niche in mining. As more mining activity is taking place in even tougher environments, requiring rugged equipment, progressive cavity pumps are will remain the obvious choice.