Water waste is usually deemed an unwanted, but inevitable by-product of mining processes. Yet modern pump sealing know-how exists which might virtually remove this waste while conserving power, enhancing pump reliability and achieving long term operational savings.
Water is considered one of the most significant, and increasingly imperilled, assets on earth. That much is known and acknowledged by industries throughout the globe.
However, it’s also one of the unnecessarily squandered sources in mining operations. And while the trade has begun to embrace effectivity and sustainability-led advances corresponding to automation and renewable vitality, it remains steadfastly set in its ways in phrases of slurry pump know-how.
Three approaches are routinely specified by pump manufacturers to seal slurry pumps: mechanical packing, expellers (also generally recognized as ‘dynamic’ seals’) and single mechanical seals. All come with vital limitations, including poor reliability, decreased imply times between failure (MTBF), intensive upkeep requirements and higher operational prices.
These factors alone should give mine managers trigger for a re-evaluation of the sealing methods used on slurry pumps. However, any firm with a commitment to the International Standards Organisation ISO-14001 Standard for environmental management methods and ISO-50001 Standard for power administration techniques ought to take notice of the excessive water waste and excessive energy consumption that outcomes from opting for these traditional 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 wasteful elements 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 supply of cool, clean flush water to be injected into the process at excessive stress, sustaining a secure fluid movie between the fragile 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 external source and injected into the process at a higher stress than the stuffing field stress, in line 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 additionally has an effect on the water steadiness of the plant.
This strategy constitutes a loss of clear water amounting to billions of gallons a year globally. One large, conventional slurry pump typically 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 surprising statistic by any measure.
At a time when world water supply is predicted to fall short of demand by some 40% by 20301 , eradicating unnecessary use of this valuable resource should arguably be a central plank of any accountable sustainability programme. Yet excessive water use, and the higher vitality consumption it entails, stay embedded within the processes of many mining corporations. Worse still, it is fair to say that it’s often accepted as simply ‘par for the course’ by reliability engineers and management alike.
But the very fact is that water waste on any scale is a totally pointless function of slurry operations as it can be nearly totally eradicated just by using advanced double mechanical seals and fashionable water management assist methods.
Improve reliability The kind of seal chosen, the environment during which it operates, and crucially, the tank assist system which supplies the water to maximise seal life, mix to offer the answer 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 ambiance, with a barrier house between the two. เกจวัดแรงดันลมขนาดเล็ก are designed to satisfy the arduous requirements of heavy responsibility slurry functions, with fortified metallic parts that are extremely proof against corrosion and erosion. Large ports and elevated radial clearances imply the lubrication which is vital to optimising seal life is maintained continually and consistently.
A pressurised barrier tank system is central to the environmental sustainability of this answer. It employs a thermosiphon process which supplies clean, cool water to the barrier house between the double seals at a strain higher than the product stress, guaranteeing a consistent, steady and clean fluid film to maintain the seal faces cool and lubricated.
As the mechanical seals generate warmth, the new water in the barrier house rises to the tank and is radiated to the environment, permitting the cooler, denser water to sink again down to supply cool lubrication to the seal faces. Most importantly, the flush water is constantly recycled, flowing across the seal faces in a continuous loop and reducing leakage to absolutely the minimum, 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 special pump techniques, pressurised barrier tanks supply scores up to 435 psi (30 bar), making them best for these purposes. Self-topping and self-pressurising, they are also virtually maintenance-free.
Where no plant water provide is out there for topping up the tank methods, or the supply has inadequate strain, fluid delivery units can be chosen to produce the barrier fluid to seal faces. These have the added benefits of having the power to provide a water/glycol combination or oil to provide freeze safety in extraordinarily chilly climates.
Wide-ranging advantages The benefits of upgrading to modern sealing solutions and help techniques had 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 large dilution of product, leading to greatly increased filtration instances and costs. The pump was sealed with a double mechanical seal designed to meet the arduous requirements of the process.
The supporting seal tank system decreased leakage and product dilution to just about zero. Return on funding was swift and the financial savings long-term. The advantages by way of water conservation have been equally longlasting and the company’s status enhanced.
The mining industry should deal with a tough and expensive problem in relation to maintaining rotating tools. But the planning, processing and disposal of flush water constitutes an operational and financial burden which is entirely avoidable.
And when an organization can remove water waste at the identical time as growing reliability and reducing long run operational costs, the choice to upgrade to fashionable techniques ought to surely be a moral imperative as nicely as making sound business sense.
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