Water waste is usually deemed an undesirable, however inevitable by-product of mining processes. Yet modern pump sealing technology exists which can just about get rid of this waste whereas conserving power, improving pump reliability and reaching long run operational savings.
Water is considered one of the most vital, and more and more imperilled, resources on earth. That much is understood and acknowledged by industries throughout the globe.
However, it’s also one of the unnecessarily squandered resources in mining operations. And whereas the trade has begun to embrace effectivity and sustainability-led advances similar to automation and renewable vitality, it stays steadfastly set in its methods when it comes to slurry pump know-how.
Three approaches are routinely specified by pump producers to seal slurry pumps: mechanical packing, expellers (also generally recognized as ‘dynamic’ seals’) and single mechanical seals. All include important limitations, including poor reliability, lowered mean occasions between failure (MTBF), intensive maintenance requirements and better operational costs.
These components alone should give mine managers trigger for a re-evaluation of the sealing strategies used on slurry pumps. However, any firm with a dedication to the International Standards Organisation ISO-14001 Standard for environmental management techniques and ISO-50001 Standard for power management systems ought to pay attention to the extreme water waste and excessive vitality consumption that outcomes from choosing 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 elements of slurry processing which is seal flush water injection.
On gland packed pumps it’s essential that packing is flushed with clean water to keep 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 strain, maintaining 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 supplied from an exterior source and injected into the process at a higher stress than the stuffing box strain, according to the trade standard American Petroleum Institute (API) Piping Plan 32. weksler ea14 which doesn’t leak onto the bottom or into the process is shipped to the tailings dam. This additionally has an effect on the water steadiness of the plant.
This strategy constitutes a loss of clean 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 yearly – a stunning statistic by any measure.
At a time when international water supply is predicted to fall wanting demand by some 40% by 20301 , removing unnecessary use of this priceless useful resource should arguably be a central plank of any accountable sustainability programme. Yet excessive water use, and the higher vitality consumption it entails, remain embedded within the processes of many mining companies. Worse nonetheless, it’s truthful to say that it is often accepted as merely ‘par for the course’ by reliability engineers and administration alike.
But the actual fact is that water waste on any scale is a totally unnecessary characteristic of slurry operations as it can be nearly totally eliminated just by using superior double mechanical seals and trendy water administration support techniques.
Improve reliability The sort of seal selected, the environment during which it operates, and crucially, the tank help system which provides the water to maximise seal life, combine to supply the solution to excessive water waste and energy use.
Modern double mechanical seals have two sets of faces, one sealing to the process fluid and one to ambiance, with a barrier house between the two. They are designed to satisfy the arduous requirements of heavy responsibility slurry applications, with fortified steel parts which are extremely immune to corrosion and erosion. Large ports and elevated radial clearances imply the lubrication which is vital to optimising seal life is maintained constantly and consistently.
A pressurised barrier tank system is central to the environmental sustainability of this answer. It employs a thermosiphon course of which supplies clean, cool water to the barrier space between the double seals at a strain higher than the product strain, guaranteeing a constant, secure and clean fluid film to maintain the seal faces cool and lubricated.
As the mechanical seals generate warmth, the new water in the barrier area rises to the tank and is radiated to the environment, permitting the cooler, denser water to sink back down to provide cool lubrication to the seal faces. Most importantly, the flush water is continually recycled, flowing throughout the seal faces in a continuous loop and lowering leakage to absolutely the minimal, roughly a teaspoonful a day.
While API Plan 32 is unsuitable for servicing a number of slurry pumps in a ‘series train’ with out the need to set up particular pump systems, pressurised barrier tanks offer scores as a lot as 435 psi (30 bar), making them best for these purposes. Self-topping and self-pressurising, they’re additionally nearly maintenance-free.
Where no plant water supply is on the market for topping up the tank systems, or the supply has inadequate stress, fluid delivery items may be selected to supply the barrier fluid to seal faces. These have the added benefits of having the flexibility to supply a water/glycol mixture or oil to supply freeze safety in extremely chilly climates.
Wide-ranging benefits The benefits of upgrading to modern sealing options and support systems 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 big dilution of product, resulting in tremendously increased filtration occasions and costs. The pump was sealed with a double mechanical seal designed to fulfill the arduous necessities of the process.
The supporting seal tank system lowered leakage and product dilution to nearly zero. Return on funding was swift and the financial savings long-term. The advantages when it comes to water conservation have been equally longlasting and the company’s popularity enhanced.
The mining industry should deal with a troublesome and costly problem in phrases of maintaining rotating gear. 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 increasing reliability and decreasing long run operational costs, the decision to improve to trendy systems should surely be a moral crucial in addition to making sound business sense.
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