One product fundamental for heavy-duty, high pressure jobs within the mining industry has been the positive displacement pump. It is a basic, yet fundamental piece of equipment that has not changed its basic function since it was introduced in the early thirties.
However, the technology and design of positive displacement pumps has changed.
This has meant an increasing demand and supply cycle for these pumps as the mining industry booms.
Positive displacement pumps are said to be the most popular pumps within the mining industry.
This is mainly due to the fact that they get the job done fast, efficiently and they are quite reliable.
The need for positive displacement pumps has been increasing for decades and has changed very little since it was introduced into the market.
What has changed is the amount of man hours and labour that has been drastically reduced with the advent of the new generation of positive displacement pumps.
Most mining companies rely on positive displacement pumps for pumping water, chemicals, slurry and various types of minerals and even solids in some cases.
Before these devices became available the labour was done by workers manually. This meant longer hours of work and it was very time consuming.
Most pipes were built from wood, which made it very difficult to maintain a constant pressure, and constant flow and drainage issues.
Many workers were also having physical problems related to the hard labour involved.
Most positive displacement pumps follow a simple formula of design and purpose.
They have an expanding cavity on the suction side and a decreasing cavity on the discharge side.
All positive displacement pumps can handle viscous liquids generally to very high viscosities and most are capable of handling substantial solids with the exception of vane, gear, multiple screw and some form of lobe pumps.
Typically, these pumps are made of aluminium, brass or bronze, cast iron, plastic or stainless steel.
The most common types of positive displacement pumps are: bladder pumps, diaphragm and double-diaphragm pumps, peristaltic pumps, gear pumps, rotary lobe pumps and progressive cavity pumps
Liquid flows into the pumps as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant given each cycle of operation.
Positive v Centrifugal
Positive displacement pumps, unlike a centrifugal pump will produce the same flow at a given speed (RPM) no matter the discharge pressure.
One company which specialises in positive displacement pumps is Kel Air Pumps; they have been selling positive displacement pumps for 25 years within the mining industry.
“The design is exactly the same as it was 20 years ago; there has, however, been an upgrade on materials and sizes to meet the current market performances,
“ You can control the pump ore precisely because the pressure does not change the rate of the pump,” Kel Air Pumps internal sales and applications engineer Alan Bethel told Australian Mining.
“Metalliferous mines use positive displacement pumps the most because they need to get rid of process waste or add chemicals at known rates, to maintain a pH at the required level.”
“In mines they can be used for other processes apart from de-watering such as, processing of ores, pumping of chemicals and slurry,” adds Bethel.
Positive displacement pumps can also be used for other applications such as cosmetics, pharmaceuticals, food and beverage, resins, adhesives and oils, inks etc.
“Australia has embraced the use of helical rotor (positive displacement) pumps for mine dewatering, where the rest of the world is still using centrifugal and piston pumps,” Mono Pumps industrial products manager Nick McNamara told Australian Mining.
“The savings substantially weigh toward the use of helical’s when you compare the difference in spare parts, maintenance & running costs required to run these types of pumps. Some of the materials I have seen put though our pumps in Australian mines would destroy a centrifugal pump within a few of days.”
“Having been in the Australian market now for over 50 years we have seen many changes. With raw materials prices continuing to climb, the most concerning change is the increasing amount of pirate spare parts which use cheaper inferior materials being introduce into the market place. Sure they may save a few dollars short term but how important is reliability to you long term?” McNamara said.