Water waste is usually deemed an undesirable, but inevitable by-product of mining processes. Yet modern pump sealing know-how exists which can just about eliminate this waste while conserving vitality, improving pump reliability and attaining long run operational savings.
Water is certainly one of the most important, and increasingly imperilled, resources on earth. That a lot is known and acknowledged by industries across the globe.
However, it’s also one of the unnecessarily squandered assets in mining operations. And whereas the trade has begun to embrace efficiency and sustainability-led advances such as automation and renewable vitality, it remains steadfastly set in its ways in relation to slurry pump technology.
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, reduced mean occasions between failure (MTBF), intensive maintenance necessities and higher operational costs.
These elements 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 administration systems and ISO-50001 Standard for vitality management techniques ought to take observe of the excessive water waste and excessive energy consumption that outcomes from choosing these conventional sealing methods.
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 some of the wasteful features of slurry processing which is seal flush water injection.
On gland packed pumps it’s important that packing is flushed with clean water to maintain it cool and lubricated, while 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 movie between the delicate seal faces to keep them cool and lubricated, whereas forcing the damaging slurry away.
The flush water required in all three sealing approaches is provided from an exterior source and injected into the method at a better pressure than the stuffing box stress, consistent with the business normal American Petroleum Institute (API) Piping Plan 32. Water which doesn’t leak onto the ground or into the method is sent to the tailings dam. This additionally has an effect on the water balance of the plant.
This approach constitutes a lack of clean water amounting to billions of gallons a yr globally. One giant, standard slurry pump sometimes 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 world water supply is predicted to fall in want of demand by some 40% by 20301 , removing pointless use of this useful useful resource should arguably be a central plank of any accountable sustainability programme. Yet excessive water use, and the upper vitality consumption it entails, stay embedded in the processes of many mining companies. Bargain , it’s honest to say that it’s typically accepted as simply ‘par for the course’ by reliability engineers and administration alike.
But the fact is that water waste on any scale is a very pointless feature of slurry operations as it can be virtually totally eradicated just by using advanced double mechanical seals and modern water administration support methods.
Improve reliability The kind of seal chosen, the environment in which it operates, and crucially, the tank support system which supplies the water to maximise seal life, combine to provide 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 environment, with a barrier house between the 2. They are designed to fulfill the arduous requirements of heavy responsibility slurry applications, with fortified metal components which are extremely immune to corrosion and erosion. Large ports and increased radial clearances imply 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 solution. It employs a thermosiphon course of which supplies clean, cool water to the barrier house between the double seals at a strain greater than the product stress, making certain a constant, steady and clear fluid film to maintain the seal faces cool and lubricated.
As the mechanical seals generate warmth, the new water within the barrier space 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 continually recycled, flowing across 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’ without the want to install particular pump systems, pressurised barrier tanks supply ratings up to 435 psi (30 bar), making them best for these functions. Self-topping and self-pressurising, they are also nearly maintenance-free.
Where no plant water provide is available for topping up the tank techniques, or the provision has inadequate strain, fluid delivery items can be chosen to produce the barrier fluid to seal faces. These have the added benefits of with the ability to supply a water/glycol combination or oil to offer freeze safety in extremely cold climates.
Wide-ranging benefits The advantages of upgrading to modern sealing solutions and support techniques were felt by a coal mine in Poland utilizing a slurry pump to supply coal mud at 9 bar (135 psi) to filter press. Flushed packing resulted in big dilution of product, resulting in tremendously increased filtration times and costs. The pump was sealed with a double mechanical seal designed to satisfy the arduous requirements 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 benefits when it comes to water conservation have been equally longlasting and the company’s status enhanced.
The mining trade must deal with a tricky and costly challenge when it comes to maintaining rotating tools. But the planning, processing and disposal of flush water constitutes an operational and financial burden which is totally avoidable.
And when a company can eliminate water waste simultaneously increasing reliability and decreasing long term operational prices, the choice to upgrade to fashionable techniques should surely be a moral crucial as well as making sound enterprise sense.
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