Water waste is often deemed an unwanted, however inevitable by-product of mining processes. Yet modern pump sealing know-how exists which might virtually remove this waste whereas conserving power, improving pump reliability and attaining long term operational savings.
Water is likely considered one of the most vital, and increasingly imperilled, resources on earth. That a lot is understood and acknowledged by industries across the globe.
However, it is also one of the unnecessarily squandered resources in mining operations. And whereas the trade has begun to embrace effectivity and sustainability-led advances corresponding to automation and renewable power, it remains steadfastly set in its methods when it comes to slurry pump know-how.
Three approaches are routinely specified by pump manufacturers to seal slurry pumps: mechanical packing, expellers (also often recognized as ‘dynamic’ seals’) and single mechanical seals. All include vital limitations, including poor reliability, reduced mean occasions between failure (MTBF), intensive upkeep requirements and better operational costs.
These components alone should give mine managers cause for a re-evaluation of the sealing methods used on slurry pumps. However, any company with a dedication to the International Standards Organisation ISO-14001 Standard for environmental administration methods and ISO-50001 Standard for power administration methods should take observe of the excessive 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 some 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 clean water to keep it cool and lubricated, while each single slurry seals and expellers require a supply of cool, clear flush water to be injected into the process at excessive pressure, sustaining a secure fluid film between the fragile 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 exterior supply and injected into the process at a higher pressure than the stuffing box stress, according to the business normal 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 additionally has an impact on the water stability of the plant.
This approach constitutes a lack of clear water amounting to billions of gallons a yr globally. One large, conventional slurry pump sometimes consumes 10 US gallons (37.8 litres) per minute, amounting to five.2 million US gallons (19.6 million litres) of water yearly – a stunning statistic by any measure.
At a time when global water supply is predicted to fall in need of demand by some 40% by 20301 , removing unnecessary use of this valuable useful resource ought to arguably be a central plank of any responsible sustainability programme. Yet excessive water use, and the upper energy consumption it entails, stay embedded in the processes of many mining companies. Worse still, it is fair to say that it’s 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 very unnecessary characteristic of slurry operations as it can be nearly totally eliminated just by employing advanced double mechanical seals and trendy water management assist methods.
Improve reliability The kind of seal selected, the surroundings in which it operates, and crucially, the tank help system which provides the water to maximise seal life, mix to provide the answer 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 environment, with a barrier house between the 2. They are designed to fulfill the arduous necessities of heavy responsibility slurry functions, with fortified metallic parts that are highly proof against corrosion and erosion. Large ports and increased radial clearances mean the lubrication which is significant to optimising seal life is maintained continually and persistently.
A pressurised barrier tank system is central to the environmental sustainability of this resolution. It employs a thermosiphon course of which supplies clear, cool water to the barrier space between the double seals at a pressure larger than the product strain, making certain a constant, steady and clear fluid film to maintain the seal faces cool and lubricated.
As the mechanical seals generate heat, the new water within the barrier area rises to the tank and is radiated to the atmosphere, allowing the cooler, denser water to sink again down to provide cool lubrication to the seal faces. เครื่องมือที่ใช้วัดความดัน , the flush water is consistently recycled, flowing across the seal faces in a continuous loop and reducing leakage to the absolute minimum, 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 special pump systems, pressurised barrier tanks supply ratings as much as 435 psi (30 bar), making them best for these functions. Self-topping and self-pressurising, they are additionally nearly maintenance-free.
Where no plant water provide is out there for topping up the tank methods, or the supply has insufficient pressure, fluid delivery units can be selected to supply the barrier fluid to seal faces. These have the added benefits of being able to provide a water/glycol combination or oil to provide freeze safety in extraordinarily chilly climates.
Wide-ranging advantages The advantages of upgrading to fashionable sealing options and help methods 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 huge dilution of product, leading to greatly increased filtration occasions 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 lowered leakage and product dilution to just about zero. Return on funding was swift and the financial savings long-term. The advantages when it comes to water conservation have been equally longlasting and the company’s popularity enhanced.
The mining industry must take care of a tough and expensive problem in relation to sustaining rotating tools. But the planning, processing and disposal of flush water constitutes an operational and financial burden which is entirely avoidable.
And when a company can eliminate water waste concurrently increasing reliability and lowering long run operational costs, the decision to improve to fashionable techniques ought to certainly be an ethical imperative in addition to making sound business sense.
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