Air operated double diaphragm pumps are found in a huge number of applications in the mining industry. Their attractive total cost of ownership is one of their key advantages.
AODD pumps are excellent all-round pumps for the mining industry, performing a range of applications from the transfer of raw materials, bulk liquids, chemicals, fuels, and mine tailings, to ground dewatering, froth flotation, water recirculation, and land reclamation.
Their widespread use is built on a number of features. They are self-priming so can run dry without any damage. They are powered entirely by compressed air, removing the need for electricity – a key requirement in many underground environments which can be explosive. And they require low maintenance. Finally, they offer an attractive cost of ownership, which is the focus of this article.
The cost of ownership of an AODD pump can be broken down into various components. These are the initial purchase price, the installation costs, maintenance and upkeep costs, spare part costs, and energy costs. Other end-of-life costs include waste removal and refurbishment costs.
This depends heavily on the pump’s materials of manufacture and its size. The AODD market is very competitive, with an extremely wide range of manufacturers and models to choose from, which has helped to keep prices competitive. If you require pulsation dampeners to accommodate vibrations and surges in the piping systems, then you need to take additional costs into consideration.
These are minimal. An AODD pump is easy to install almost anywhere, as long as there is sufficient space. Even in the mining industry where space underground can be limited, this is generally not an issue as most AODD pumps have small footprints. These pumps can even be submerged if the liquid is compatible with the material of the pump and the exhaust is ported out of the liquid.
One of the most significant benefits of AODD pumps is their high reliability – an absolute must in underground mining applications where maintenance personnel might be few and far between. Their high reliability is based on very few moving parts, and a limited number of components that can wear. The main working parts are the valves, valve seats and diaphragms. Should maintenance be necessary – for example for a diaphragm replacement – an AODD pump is easy to dismantle.
Spare part costs
AODD pump spares are generally fairly low cost. However, it is vital to select the correct corresponding spare parts. This is particularly important when selecting a replacement diaphragm. The diaphragm used must be compatible with the fluid to be pumped. At the same time, don’t over-specify because this simply leads to unnecessary costs. Neoprene is a good general purpose and low cost diaphragm that delivers high flex life. Teflon-based diaphragms are generally the most expensive, with other materials lying in between.
The main running cost of an AODD pump relates to the consumption of the compressed air that is required to power the pump. Compressed air requires air compressors and air distribution systems, making it a relatively costly utility. But in many situations, such as hazardous areas where an electricity supply is forbidden, or areas where electricity simply is not available, centrifugal and positive displacement pumps can not be used, so AODD pumps prove indispensable.
Waste removal costs
Waste removal costs are nil. AODD pumps are generally environmentally friendly as most of them use oil-free compressed air for pollution-free operation. This means that no oil mist is vented into the atmosphere and no oil contamination of the pumped fluid is possible.
As an AODD pump contains few components that require maintenance, refurbishment is a distinct possibility and is actually a fairly straightforward process. Refurbishment not only increases the lifetime of an AODD pump but further decreases its total cost of ownership.
Graco offers a wide range of AODD pumps that are suitable for applications in the mining industry. One of its best-selling AODD pumps – and one that is in service with many mining operators all over the world – is the Husky 1050. This is a 1-inch (25.4 mm) AODD pump that is available in aluminium, polypropylene, conductive polypropylene, PVDF, stainless steel and hastelloy. It offers a diaphragm life that is up to five times longer compared to other diaphragm pumps in its class. Spring loaded, externally serviceable pilot valves ensure fast change-over and low pulsation.
The Husky 1050 is submersible, intrinsically safe (available in ATEX configuration) and lube-free. It can run dry, and has outstanding anti-freezing properties. It has a maximum fluid flow of 50 gpm (189 l/min), and a maximum fluid discharge pressure of 125 psi (8.6 bar, 0.86 MPa). It is capable of pumping solids of size up to 1/8 inch (3.2 mm), and offers a fluid displacement per cycle of 0.17 g (0.64 liters).
It is manufactured according to Quality Management System ISO 9001, Environmental Management System ISO 14001, and Occupational Health and Safety Advisory Services OHSAS 18001 standards.