Pattern is usually deemed an unwanted, however inevitable by-product of mining processes. Yet trendy pump sealing expertise exists which might virtually eliminate this waste while conserving vitality, improving pump reliability and reaching long run operational savings.
Water is certainly one of the most vital, and more and more imperilled, resources on earth. That much is understood and acknowledged by industries across the globe.
However, it is also some of the unnecessarily squandered resources in mining operations. And while the industry has begun to embrace efficiency and sustainability-led advances similar to automation and renewable energy, it stays steadfastly set in its ways when it comes 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, decreased mean occasions between failure (MTBF), intensive upkeep requirements and better operational costs.
These factors alone should give mine managers cause 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 administration methods and ISO-50001 Standard for energy management systems should pay attention to the extreme water waste and excessive energy consumption that outcomes from opting for these traditional 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 aspects of slurry processing which is seal flush water injection.
On gland packed pumps it’s important that packing is flushed with clear water to maintain it cool and lubricated, whereas each single slurry seals and expellers require a provide of cool, clear flush water to be injected into the method at excessive strain, sustaining a steady 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 supplied from an exterior supply and injected into the process at the next pressure than the stuffing box pressure, consistent with the trade normal 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 effect on the water balance of the plant.
This method constitutes a lack of clean water amounting to billions of gallons a year globally. One massive, conventional slurry pump usually consumes 10 US gallons (37.eight litres) per minute, amounting to 5.2 million US gallons (19.6 million litres) of water every year – a stunning statistic by any measure.
At a time when international water supply is predicted to fall in want of demand by some 40% by 20301 , eradicating unnecessary use of this useful resource ought to arguably be a central plank of any accountable sustainability programme. Yet excessive water use, and the higher power consumption it entails, remain embedded in the processes of many mining firms. Worse still, it is honest to say that it is often 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 unnecessary function of slurry operations as it may be almost totally eradicated simply by employing advanced double mechanical seals and modern water management support methods.
Improve reliability The sort of seal selected, the surroundings during which it operates, and crucially, the tank support system which supplies the water to maximise seal life, mix to supply the solution to extreme water waste and vitality use.
Modern double mechanical seals have two units of faces, one sealing to the process fluid and one to ambiance, with a barrier area between the two. They are designed to fulfill the arduous requirements of heavy responsibility slurry applications, with fortified metallic components that are extremely resistant to corrosion and erosion. Large ports and elevated radial clearances imply the lubrication which is important to optimising seal life is maintained continuously and consistently.
A pressurised barrier tank system is central to the environmental sustainability of this resolution. It employs a thermosiphon course of which provides clear, cool water to the barrier space between the double seals at a strain larger than the product stress, ensuring a consistent, secure and clear fluid movie to keep the seal faces cool and lubricated.
As the mechanical seals generate warmth, the new water in the barrier space rises to the tank and is radiated to the atmosphere, allowing the cooler, denser water to sink again down to offer cool lubrication to the seal faces. Most importantly, the flush water is consistently recycled, flowing across the seal faces in a continuous loop and reducing leakage to the absolute minimal, roughly a teaspoonful a day.
While API Plan 32 is unsuitable for servicing a quantity of slurry pumps in a ‘series train’ without the necessity to set up particular pump methods, pressurised barrier tanks offer scores up to 435 psi (30 bar), making them best for these applications. Self-topping and self-pressurising, they are also almost maintenance-free.
Where no plant water supply is on the market for topping up the tank systems, or the availability has insufficient stress, fluid supply models can be chosen to produce the barrier fluid to seal faces. These have the added advantages of with the flexibility to supply a water/glycol combination or oil to offer freeze safety in extremely chilly climates.
Wide-ranging advantages The advantages of upgrading to fashionable sealing solutions and assist methods had been felt by a coal mine in Poland using a slurry pump to supply coal mud at 9 bar (135 psi) to filter press. Flushed packing resulted in big dilution of product, leading to significantly elevated filtration times and prices. The pump was sealed with a double mechanical seal designed to meet the arduous requirements of the method.
The supporting seal tank system reduced leakage and product dilution to nearly zero. Return on investment was swift and the financial savings long-term. The advantages by way of water conservation have been equally longlasting and the company’s reputation enhanced.
The mining business must take care of a troublesome and costly problem when it comes 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 an organization can eliminate water waste simultaneously increasing reliability and reducing long run operational prices, the decision to upgrade to modern methods ought to absolutely be a moral crucial as well as making sound business sense.
Share