February 2018

Ten warning signs when monitoring your processing equipment

  • By Marcus Lane, Global Product Manager of Centrifugal Pumps, Weir Minerals

An overview of common indicators that highlight potential areas for improvement in processing equipment monitoring and maintenance

The efficiency and reliability of your processing equipment is inseparable from your bottom line. Regardless of the size of your mining operation, the inevitable and excessive costs incurred from equipment that hasn’t been properly maintained can seriously threaten your balance sheet, as well as the health and safety of workers and the surrounding environment.

Regular monitoring is key to ensuring reliable performance from all minerals processing equipment. A vigilant condition-monitoring protocol that takes note of overall equipment performance and the condition of wear parts will prevent potential hazards and allow for efficient scheduling of any necessary maintenance. The effects on your bottom line and on-site health and safety will be clear.

Wear and tear is unavoidable, particularly when it comes to wet processes, but if your staff are well trained to recognise the warning signs of suboptimal performance, unavoidable wear and tear doesn’t have to result in an avoidable accident or disaster. With that in mind, let’s take a look at the ten biggest symptoms of equipment in need of maintenance or replacement.

1. Excessive leakage

Excessive product leakage is one of the prime indicators that something isn’t right with your equipment. Excessive leakage from pumps requires immediate inspection and maintenance and could be a symptom of an issue with the equipment’s shaft seal or hydraulic end.

You could also be experiencing issues with worn liners. Slurry handling equipment contains liners designed to prevent leakage and improve flow path. However, excessive liner wear can lead to a reduction in throughput as well as significant leakage.

Quality suppliers will offer maintenance on any onsite equipment. If your condition-monitoring protocol has indicated unusual leakage from wet process equipment, schedule an inspection with the equipment manufacturer as soon as possible.

2. Poor bearing condition

Worn or damaged bearings in rotating equipment increase vibration, creating high noise levels and increasing the likelihood of damaged equipment. The importance of a pump’s bearing assembly cannot be overstated, so it’s imperative that bearings are properly maintained.

However, the condition of the bearing assembly is easy to monitor and maintain, provided an operation is mindful of condition monitoring. Well-lubricated bearings that are shielded from moisture will reduce the build-up of corrosion, thus reducing the assembly’s rate of wear and extending its overall lifespan.

3. Excessive vibration

Like many of the warning signs on this list, some vibration is to be expected in certain equipment, but unusually high levels can be a cause for concern. Worn bearings, improper installation or misaligned belt drive systems are all potential causes of excessive vibration.

The best way to ensure vibration is at normal levels is to monitor it over time and take note of patterns and unusual fluctuations. Doing so will prevent equipment damage should a sudden spike arise.

4. Unusual power consumption

The same principle that applies to vibration applies to power consumption – keep an eye out for anything unusual. It’s not unusual for minerals processing equipment to consume a large amount of energy, but sudden dramatic spikes or significant decreases in power consumption could indicate a potential fault.

Power consumption will fluctuate over the life of an operation. A good monitoring protocol will account for this by detailing patterns, as well as setting ranges and detailing anything that could potentially cause a spike or dip in power consumption.

Implementing this as part of your onsite protocol will ensure any issues with equipment are identified early and resolved with minimal interruption to your operation and without incident.

5. Gland leakage

If the shaft seal on a centrifugal pump utilises gland packings, it is imperative that proper maintenance is adhered to. Gland packings are stored in a stuffing box. Wear and tear or improperly compressed packing can leak, which can pose serious issues, particularly when handling abrasive or corrosive compounds.

Ensure workers are diligent about the health of shaft seals and consider an alternative sealing method if gland leakage is a recurring issue. Alternatives include centrifugal seals and single or double mechanical seals.

6. Parts wear

Wear is inevitable, particularly in pumps, screens and cyclones, and there are numerous factors at play when it comes to the rate at which your equipment will begin to degrade. Factors include the slurry and operating points; alterations to process, such as changes in pipe lengths and materials; and changes in parts such as hydraulics. All of these will affect the rate of wear and may cause it to increase or decrease.

You can take steps to exercise control over the rate of wear. Wear-resistant materials that protect parts are available, and sophisticated modern hydraulics greatly improve the passage of material through pumps and cyclones. As always, an adequate monitoring protocol will ensure any leaks or power fluctuations are noted and any maintenance is requested when needed.

7. Poor belt tension and alignment

Belt drives can be a double-edged sword when it comes to pump performance. When correctly aligned, tensioned and regularly maintained, belt drives can be one of the best ways to operate certain pumps. However, a belt drive that hasn’t been correctly set up or a belt drive that’s been neglected can significantly compromise pump performance.

Belt failure often follows the same pattern. An inadequately tensioned belt creates excessive vibration in a pump and slippage causes heat build-up, which leads to the eventual failure of the belt drive system. Alternatively, an excessively tensioned belt places strain on the bearing assembly, leading to accelerated wear.

To prevent this from happening in your operation, ensure belt drives are properly installed or employ a hydraulic belt tensioning system, which will provide correct tensioning and alignment and significantly reduce maintenance time.

8. Poor system flow rate

Fluid flow rate is one of the key metrics of any pump condition monitoring system. As part of your protocol, the flow rate should be within a range considered normal for the process (a flotation circuit, for example), as fluctuations outside of acceptable tolerance have myriad implications, affecting the balance of the entire process.

An unusually low flow rate should alert you to potential wear in pump parts and poor efficiency, which should prompt inspection by a technician. The low flow rate is easier to identify if ongoing monitoring is taking place and benchmarks are set for adequate fluid flow rate. Ensure your condition monitoring system includes a flow rate inspection and an adequate process to follow should flow rate show any unusual fluctuation.

While accurate monitoring of system flow rate can require expensive measuring equipment, properly maintained equipment will reduce the cost of ownership in the long run and improve the efficiency of your mine. Proper monitoring equipment can provide a clear picture of the throughput of your process equipment, and allow you to more easily detect changes in flow rate and prevent process imbalance before it becomes a more critical issue.

9. Uneven liner wear

Even wear in slurry handling equipment will maximise the life of your equipment and optimise wear life. The internal profile of your equipment is critical to how evenly parts sustain wear, which is in turn critical to the lifespan of your equipment. Uneven or localised wear can result in significant damage to your equipment and is often a sign of a turbulent flow passage caused by unsuitable construction materials, incorrect operating points, improper application of equipment, improper sizing of equipment or poor hydraulic design.

Liner wear should be monitored with regular inspections by a service technician. The technician will be able to measure the level of wear sustained by a part and advise whether the part requires replacing. Regular inspections will not only increase process efficiency and maximise service life, it can reduce total cost of ownership and, more importantly, prevent downtime and environmental issues caused by a breach.

10. Low mean time between failures

One of the biggest advantages of proper monitoring and regular inspection and maintenance is a dramatic increase in mean time between failures (MTBF); ie, the time that elapses between failures of a mechanical part. A low MTBF, where equipment experiences frequent failure, is one of the clearest signs of equipment that’s not capable of handling a process or an inadequate maintenance schedule and is one of the easiest variables to measure in your monitoring protocol.

MTBF is a critical metric for any mining operation and it’s imperative that a strict eye is kept on an unusually low MTBF. Suboptimal performance in equipment will be easy to identify and proper monitoring of the issue will allow you to more easily analyse the effects of changes to on-site processes or to equipment. If equipment is indicating low MTBF, bring it to the attention of a technician and replace any worn or damaged parts or upgrade the equipment entirely.

Feature image: only_kim/Shutterstock.com.

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