Water waste is often deemed an unwanted, however inevitable by-product of mining processes. Yet modern pump sealing know-how exists which can virtually remove this waste whereas conserving energy, improving pump reliability and attaining long term operational savings.
Water is among the most important, and increasingly imperilled, assets on earth. That a lot is understood and acknowledged by industries throughout the globe.
However, it’s also one of the most unnecessarily squandered resources in mining operations. And whereas the industry has begun to embrace effectivity and sustainability-led advances corresponding to automation and renewable vitality, it remains steadfastly set in its methods in relation to slurry pump expertise.
Three approaches are routinely specified by pump producers to seal slurry pumps: mechanical packing, expellers (also often identified as ‘dynamic’ seals’) and single mechanical seals. All come with important limitations, including poor reliability, reduced mean times between failure (MTBF), intensive upkeep requirements and better operational costs.
Track record ought to give mine managers trigger for a re-evaluation of the sealing methods used on slurry pumps. However, any firm with a dedication to the International Standards Organisation ISO-14001 Standard for environmental administration systems and ISO-50001 Standard for power management techniques ought to take note of the extreme water waste and high energy 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 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 keep it cool and lubricated, whereas each single slurry seals and expellers require a provide of cool, clean flush water to be injected into the method at excessive stress, sustaining a steady fluid film between the delicate seal faces to maintain them cool and lubricated, whereas forcing the damaging slurry away.
The flush water required in all three sealing approaches is provided from an exterior supply and injected into the method at the next stress than the stuffing field pressure, according to the trade 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 stability of the plant.
This strategy constitutes a lack of clean water amounting to billions of gallons a 12 months globally. One giant, typical slurry pump usually consumes 10 US gallons (37.eight 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 global water provide is predicted to fall in want of demand by some 40% by 20301 , removing unnecessary use of this priceless useful resource ought to arguably be a central plank of any accountable sustainability programme. Yet extreme water use, and the upper vitality consumption it entails, remain embedded within the processes of many mining firms. Worse still, it’s fair to say that it’s usually accepted as simply ‘par for the course’ by reliability engineers and management alike.
But the fact is that water waste on any scale is a completely unnecessary function of slurry operations as it can be virtually totally eliminated just by using advanced double mechanical seals and fashionable water administration help techniques.
Improve reliability The type of seal chosen, the environment during which it operates, and crucially, the tank support system which supplies the water to maximise seal life, combine to supply the solution to excessive water waste and power use.
Modern double mechanical seals have two sets of faces, one sealing to the method fluid and one to ambiance, with a barrier house between the two. They are designed to satisfy the arduous necessities of heavy duty slurry functions, with fortified metal elements which are highly proof against corrosion and erosion. Large ports and elevated radial clearances mean the lubrication which is significant to optimising seal life is maintained continuously and consistently.
A pressurised barrier tank system is central to the environmental sustainability of this answer. It employs a thermosiphon course of which supplies clear, cool water to the barrier house between the double seals at a stress larger than the product strain, ensuring a consistent, steady and clear fluid movie to maintain the seal faces cool and lubricated.
As the mechanical seals generate heat, the recent water in the barrier space 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 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 want to set up special pump systems, pressurised barrier tanks supply ratings as much as 435 psi (30 bar), making them perfect for these purposes. Self-topping and self-pressurising, they are additionally virtually maintenance-free.
Where no plant water supply is out there for topping up the tank systems, or the supply has inadequate pressure, fluid supply items could 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 offer freeze protection in extraordinarily chilly climates.
Wide-ranging advantages The benefits of upgrading to fashionable sealing solutions and assist systems were felt by a coal mine in Poland utilizing a slurry pump to provide coal mud at 9 bar (135 psi) to filter press. Flushed packing resulted in huge dilution of product, resulting in significantly elevated filtration instances and prices. The pump was sealed with a double mechanical seal designed to meet the arduous necessities of the method.
The supporting seal tank system decreased leakage and product dilution to just about zero. Return on funding was swift and the savings long-term. The benefits when it comes to water conservation have been equally longlasting and the company’s reputation enhanced.
The mining industry must take care of a tough and costly problem in terms of sustaining rotating gear. But the planning, processing and disposal of flush water constitutes an operational and monetary burden which is totally avoidable.
And when an organization can get rid of water waste concurrently rising reliability and reducing long term operational costs, the decision to improve to trendy systems should certainly be an ethical crucial as nicely as making sound business sense.
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