Water waste is usually deemed an unwanted, however inevitable by-product of mining processes. Yet modern pump sealing technology exists which may just about get rid of this waste while conserving power, improving pump reliability and achieving long run operational savings.
Water is certainly one of the most vital, and increasingly imperilled, assets on earth. That much is understood and acknowledged by industries throughout the globe.
However, it’s also one of the most unnecessarily squandered assets in mining operations. And whereas the business has begun to embrace effectivity and sustainability-led advances corresponding to automation and renewable energy, it stays steadfastly set in its ways in terms of slurry pump know-how.
Three approaches are routinely specified by pump producers to seal slurry pumps: mechanical packing, expellers (also often recognized as ‘dynamic’ seals’) and single mechanical seals. All come with vital limitations, together with poor reliability, decreased imply times between failure (MTBF), intensive upkeep necessities and higher operational costs.
These components alone ought to give mine managers cause for a re-evaluation of the sealing strategies used on slurry pumps. However, any company with a dedication to the International Standards Organisation ISO-14001 Standard for environmental management systems and ISO-50001 Standard for power management techniques ought to take note of the excessive water waste and excessive energy consumption that results from opting for these conventional sealing strategies.
Inefficient sealing When used to seal the process pumps in a mine’s scrubber and floatation circuits, gland packing, single mechanical seals and expeller seals all demand one of the most wasteful features of slurry processing which is seal flush water injection.
On gland packed pumps it’s essential that packing is flushed with clean water to maintain it cool and lubricated, whereas both single slurry seals and expellers require a supply of cool, clear flush water to be injected into the method at high stress, sustaining a steady fluid film between the fragile seal faces to maintain them cool and lubricated, whereas forcing the damaging slurry away.
The flush water required in all three sealing approaches is equipped from an exterior supply and injected into the method at a higher pressure than the stuffing field pressure, according to the industry standard American Petroleum Institute (API) Piping Plan 32. Water which doesn’t leak onto the bottom or into the process is shipped to the tailings dam. This also has an effect on the water balance of the plant.
This strategy constitutes a lack of clear water amounting to billions of gallons a 12 months globally. One giant, standard slurry pump usually consumes 10 US gallons (37.8 litres) per minute, amounting to five.2 million US gallons (19.6 million litres) of water every year – a surprising statistic by any measure.
At a time when world water provide is predicted to fall in want of demand by some 40% by 20301 , eradicating pointless use of this valuable useful resource should arguably be a central plank of any accountable sustainability programme. Yet extreme water use, and the upper energy consumption it entails, stay embedded within the processes of many mining corporations. Worse nonetheless, it’s fair to say that it’s typically accepted as merely ‘par for the course’ by reliability engineers and management alike.
But the very fact is that water waste on any scale is a totally pointless function of slurry operations as it can be nearly completely eradicated just by employing superior double mechanical seals and fashionable water management assist methods.
Improve reliability The sort of seal selected, the environment during which it operates, and crucially, the tank help system which supplies the water to maximise seal life, mix to provide the solution to extreme water waste and power use.
Modern double mechanical seals have two sets of faces, one sealing to the process fluid and one to atmosphere, with a barrier house between the two. They are designed to fulfill the arduous necessities of heavy obligation slurry applications, with fortified metallic elements that are extremely proof against corrosion and erosion. Large ports and elevated radial clearances mean the lubrication which is significant to optimising seal life is maintained constantly and constantly.
A pressurised barrier tank system is central to the environmental sustainability of this solution. It employs a thermosiphon process which provides clean, cool water to the barrier house between the double seals at a strain larger than the product stress, ensuring a constant, stable and clean fluid movie to keep the seal faces cool and lubricated.
As the mechanical seals generate warmth, the new water within the barrier house rises to the tank and is radiated to the environment, allowing the cooler, denser water to sink back down to supply cool lubrication to the seal faces. Most importantly, the flush water is consistently recycled, flowing throughout the seal faces in a continuous loop and decreasing leakage to the absolute minimal, roughly a teaspoonful a day.
While API Plan 32 is unsuitable for servicing multiple slurry pumps in a ‘series train’ without the want to install particular pump systems, pressurised barrier tanks provide ratings up to 435 psi (30 bar), making them perfect for these functions. Self-topping and self-pressurising, they are additionally virtually maintenance-free.
Where no plant water supply is out there for topping up the tank techniques, or the supply has insufficient pressure, fluid delivery items may be chosen to produce the barrier fluid to seal faces. These have the added advantages of having the flexibility to provide a water/glycol combination or oil to offer freeze protection in extraordinarily cold climates.
Wide-ranging benefits The advantages of upgrading to modern sealing options and help methods had been felt by a coal mine in Poland using a slurry pump to produce coal mud at 9 bar (135 psi) to filter press. Flushed packing resulted in large dilution of product, leading to greatly elevated filtration times and prices. The pump was sealed with a double mechanical seal designed to fulfill the arduous necessities of the method.
The supporting seal tank system decreased leakage and product dilution to just about zero. Return on investment was swift and the financial savings long-term. The advantages in phrases of water conservation have been equally longlasting and the company’s popularity enhanced.
pressure gauge mining business must take care of a tough and costly problem in relation to maintaining rotating tools. But the planning, processing and disposal of flush water constitutes an operational and monetary burden which is entirely avoidable.
And when a company can remove water waste simultaneously growing reliability and lowering long run operational costs, the choice to upgrade to modern techniques should surely be an ethical crucial in addition to making sound enterprise sense.
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