Water waste is commonly deemed an undesirable, however inevitable by-product of mining processes. Yet fashionable pump sealing know-how exists which might just about remove this waste whereas conserving power, bettering pump reliability and reaching long term operational savings.
Water is amongst the most vital, and increasingly imperilled, sources on earth. That much is understood and acknowledged by industries across the globe.
However, it’s also one of the most unnecessarily squandered resources in mining operations. And while the trade has begun to embrace efficiency and sustainability-led advances similar to automation and renewable energy, it remains steadfastly set in its methods in terms of slurry pump know-how.
Three approaches are routinely specified by pump producers to seal slurry pumps: mechanical packing, expellers (also generally identified as ‘dynamic’ seals’) and single mechanical seals. All come with vital limitations, together with poor reliability, decreased imply occasions between failure (MTBF), intensive upkeep requirements 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 firm with a commitment to the International Standards Organisation ISO-14001 Standard for environmental management techniques and ISO-50001 Standard for energy administration methods should pay consideration to the excessive water waste and excessive power consumption that outcomes from choosing these traditional sealing methods.
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 wasteful elements of slurry processing which is seal flush water injection.
On gland packed pumps it’s essential that packing is flushed with clear water to maintain it cool and lubricated, whereas each single slurry seals and expellers require a supply of cool, clear flush water to be injected into the process at high stress, sustaining a secure 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 supplied from an external source and injected into the process at a better stress than the stuffing field strain, consistent with the industry commonplace American Petroleum Institute (API) Piping Plan 32. Water which doesn’t leak onto the bottom or into the process is sent to the tailings dam. This also has an effect on the water steadiness of the plant.
This approach constitutes a lack of clean water amounting to billions of gallons a yr globally. One massive, standard 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 stunning statistic by any measure.
At a time when global water provide is predicted to fall in need of demand by some 40% by 20301 , eradicating unnecessary use of this priceless useful resource should arguably be a central plank of any responsible sustainability programme. Yet excessive water use, and the higher energy consumption it entails, stay embedded in the processes of many mining firms. Worse nonetheless, it is truthful to say that it is often accepted as merely ‘par for the course’ by reliability engineers and administration alike.
But the very fact is that water waste on any scale is a totally unnecessary characteristic of slurry operations as it can be almost totally eradicated just by employing superior double mechanical seals and trendy water administration assist techniques.
Improve reliability The type of seal chosen, the setting by which it operates, and crucially, the tank assist system which supplies the water to maximise seal life, mix to provide the solution to extreme water waste and vitality use.
Modern double mechanical seals have two units of faces, one sealing to the method fluid and one to environment, with a barrier area between the two. They are designed to meet the arduous necessities of heavy responsibility slurry functions, with fortified steel elements which are highly proof against corrosion and erosion. Large ports and elevated radial clearances mean 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 solution. It employs a thermosiphon course of which supplies clean, cool water to the barrier space between the double seals at a stress greater than the product strain, guaranteeing a consistent, secure and clean fluid movie to maintain the seal faces cool and lubricated.
As the mechanical seals generate heat, the recent water within the barrier area rises to the tank and is radiated to the atmosphere, allowing 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 steady loop and decreasing leakage to absolutely the minimal, roughly a teaspoonful a day.
While API Plan 32 is unsuitable for servicing multiple slurry pumps in a ‘series train’ with out the necessity to set up particular pump techniques, pressurised barrier tanks supply rankings as much as 435 psi (30 bar), making them perfect for these functions. เกจวัดแรงดันลม -topping and self-pressurising, they are additionally almost maintenance-free.
Where no plant water supply is out there for topping up the tank systems, or the availability has insufficient stress, fluid delivery units could be selected to supply the barrier fluid to seal faces. These have the added benefits of with the power to provide a water/glycol combination or oil to supply freeze protection in extremely chilly climates.
Wide-ranging benefits The advantages of upgrading to fashionable sealing options and help techniques have been 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 huge dilution of product, leading to greatly increased filtration occasions 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 lowered leakage and product dilution to virtually zero. Return on funding was swift and the savings long-term. The advantages when it comes to water conservation have been equally longlasting and the company’s status enhanced.
The mining industry should cope with a tough and dear challenge in phrases of 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 remove water waste at the identical time as rising reliability and lowering long run operational prices, the choice to upgrade to trendy methods ought to absolutely be a moral crucial in addition to making sound enterprise sense.
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