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Water waste is usually deemed an undesirable, but inevitable by-product of mining processes. Yet fashionable pump sealing technology exists which may virtually remove this waste while conserving vitality, improving pump reliability and achieving long run operational savings.
Water is one of the most significant, and more and more imperilled, resources on earth. That much is understood and acknowledged by industries across the globe.
However, additionally it is one of the most unnecessarily squandered assets in mining operations. And while the industry has begun to embrace effectivity and sustainability-led advances corresponding to automation and renewable vitality, it stays steadfastly set in its ways in relation to slurry pump technology.
Three approaches are routinely specified by pump manufacturers to seal slurry pumps: mechanical packing, expellers (also known as ‘dynamic’ seals’) and single mechanical seals. All come with important limitations, including poor reliability, lowered mean times between failure (MTBF), intensive maintenance necessities and higher operational costs.
These elements alone should give mine managers cause for a re-evaluation of the sealing strategies used on slurry pumps. However, any company with a commitment to the International Standards Organisation ISO-14001 Standard for environmental administration methods and ISO-50001 Standard for vitality management methods should take note of the excessive water waste and excessive energy consumption that results from choosing these conventional sealing strategies.
Inefficient sealing When used to seal the method pumps in a mine’s scrubber and floatation circuits, gland packing, single mechanical seals and expeller seals all demand one of the wasteful elements of slurry processing which is seal flush water injection.
On gland packed pumps it’s important that packing is flushed with clear water to keep it cool and lubricated, while both single slurry seals and expellers require a supply of cool, clear flush water to be injected into the process at high stress, maintaining a stable fluid film between the fragile seal faces to maintain them cool and lubricated, while 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 stress than the stuffing field stress, in line with the trade standard American Petroleum Institute (API) Piping Plan 32. Water which doesn’t leak onto the bottom or into the method is shipped to the tailings dam. This additionally has an impact on the water stability of the plant.
This approach constitutes a loss of clear water amounting to billions of gallons a year globally. One giant, standard slurry pump sometimes 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 shocking statistic by any measure.
At a time when world water provide is predicted to fall wanting demand by some 40% by 20301 , removing pointless use of this valuable useful resource should arguably be a central plank of any responsible sustainability programme. Yet extreme water use, and the upper power consumption it entails, remain embedded within the processes of many mining firms. Worse still, it is truthful to say that it’s often accepted as merely ‘par for the course’ by reliability engineers and administration alike.
But the fact is that water waste on any scale is a totally pointless feature of slurry operations as it may be almost totally eradicated simply by using superior double mechanical seals and fashionable water administration assist systems.
Improve reliability The kind of seal chosen, the setting by which it operates, and crucially, the tank assist system which provides the water to maximise seal life, combine to provide the answer to extreme water waste and power use.
Modern double mechanical seals have two units of faces, one sealing to the method fluid and one to environment, with a barrier house between the 2. They are designed to fulfill the arduous requirements of heavy obligation slurry functions, with fortified steel components which are extremely proof against corrosion and erosion. Large ports and increased radial clearances mean the lubrication which is important to optimising seal life is maintained continually and constantly.
Price break is central to the environmental sustainability of this resolution. It employs a thermosiphon course of which provides clean, cool water to the barrier area between the double seals at a strain larger than the product stress, guaranteeing a consistent, secure and clear fluid movie to maintain the seal faces cool and lubricated.
As the mechanical seals generate warmth, the hot water in the barrier area rises to the tank and is radiated to the ambiance, allowing the cooler, denser water to sink back down to supply cool lubrication to the seal faces. Most importantly, the flush water is constantly recycled, flowing across the seal faces in a steady loop and reducing leakage to absolutely the minimum, 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 special pump systems, pressurised barrier tanks offer ratings as a lot as 435 psi (30 bar), making them perfect for these purposes. Self-topping and self-pressurising, they are also almost maintenance-free.
Where no plant water supply is out there for topping up the tank techniques, or the availability has insufficient stress, fluid delivery models can be selected to produce the barrier fluid to seal faces. These have the added benefits of having the ability to provide a water/glycol combination or oil to offer freeze protection in extremely chilly climates.
Wide-ranging benefits The advantages of upgrading to fashionable sealing solutions and assist techniques were felt by a coal mine in Poland using a slurry pump to provide coal mud at 9 bar (135 psi) to filter press. Flushed packing resulted in large dilution of product, leading to tremendously increased filtration times and costs. The pump was sealed with a double mechanical seal designed to meet the arduous necessities of the process.
The supporting seal tank system decreased leakage and product dilution to virtually zero. Return on investment was swift and the financial savings long-term. The advantages by means of water conservation have been equally longlasting and the company’s popularity enhanced.
The mining business must cope with a tough and expensive problem in terms of sustaining rotating tools. But the planning, processing and disposal of flush water constitutes an operational and financial burden which is entirely avoidable.
And when a company can remove water waste at the identical time as growing reliability and lowering long term operational costs, the decision to improve to modern techniques ought to surely be an ethical imperative as properly as making sound business sense.
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