Erosion of plant equipment

by Mark Cooksey

Reducing the cost of erosion through fluids engineering

Erosion is a well-recognised issue in minerals processing and one that many operators are dealing with on a regular basis. It is exacerbated by the prevalence of slurries in mineral processing operations.

While erosion is generally a slow phenomenon, the nature of slurry material can lead to accelerated erosion. This often results in operators having to replace equipment frequently, and at great expense.

While the significant expenditure required to address the consequences of premature erosion are unwelcome, they are, for the most part, accepted.

However, with the lifespan of equipment fluctuating anywhere between years, months and weeks, this expenditure can easily grow beyond budget and lead to unexpected – and hazardous – equipment failure.

While replacing equipment might be easier in the short term, reducing or even eliminating erosion presents an opportunity to achieve massive cost-savings for your operations and all but eradicate your risk.

Equipment replacement can soon exceed the expected cost and risk

Replacing mineral processing equipment to combat erosion is so common that it is built into annual budgets.

But while many operations prepare in advance for equipment replacement, it’s almost impossible to determine exactly when a replacement will be required – until you experience a failure. Because of this, many will use historical lifespan data to plan when they will replace current equipment. However, by relying on this method you either risk failure by not replacing soon enough or face the high costs of replacing too frequently.

The more you consider the risk and cost to operations, the less viable the ‘solution’ of equipment replacement seems.

• High costs for equipment repair and replacement As we’ve discussed, the lifespan of equipment can vary, meaning the expenditure required to repair and replace your equipment is likely to continue to grow well past budgeted amounts.
• Equipment failure Failing to notice a fault or replace equipment in time can lead to complete failure. This affects productivity and can be hazardous to people and the surrounding environment.
• Diminished process performance Eroded equipment often cannot perform at the expected or required capacity. Production and revenue are lost through both increased energy costs and depleted ability of equipment to perform at the required rate.

Prevention strategies offer longer-term benefits

Even with the many risks and costs, replacing equipment is the preferred solution for many operators. It can seem like a simpler and quicker option, but it does nothing to address the root cause – the erosion itself.

By switching your focus to prevention rather than treatment, you can combat not only premature erosion but also the financial and safety risks it presents.

This is the idea behind implementing fluids engineering and materials solutions. These can decrease risk without disrupting production.

Fluid engineering works to mitigate erosion by modifying fluid flows, including:

• reducing flow velocity
• reducing flow disturbances
• moving flow disturbances from vulnerable surfaces to free stream areas, and
• homogenising velocity fields as much as possible.

Fluids engineering is often not regarded as a possible solution to premature erosion due to the perceived difficulty and time commitment required. However, investment in the short term has shown to produce long term benefits.

Fluids engineering in action

At an Australian alumina refinery, constant bombardment of the cooling plates by abrasive hydrated alumina particles in the slurry was forcing the plant operator to replace some plates as frequently as every few days.

After they decided to engage CSIRO, we suggested a way to make the slurry flow more consistent by inserting a form of mesh to homogenise the flow. This eliminated the peak hot spots and minimised damage to the cooling plates.

The benefits of the improvements have been dramatic. The life expectancy of cooling plates has been extended from a few days to as long as 12 months, representing a major saving in the maintenance costs. The biggest reward, however, was minimising plant shutdowns and maximising production.

Use our expertise to reduce erosion

Utilising fluids engineering and materials to combat premature erosion requires expertise in multiple areas.

With extensive experience in both mineral processing and fluids engineering, we have the capability and experience to understand the type of problems your operation is facing and conduct research and development in the most effective and efficient way to deliver a solution.

CSIRO Fluids Engineering conducts fundamental and applied erosion research with the aim of reducing erosion of mineral processing equipment.

Our facilities, equipment and machines allow for accelerated testing and modelling, removing pressure on your plant and providing more accurate solutions in a shorter time frame.

Through modifying the geometry and fluid dynamics, we have solved premature erosion in various equipment, including:

• reducing erosion in plate heat exchangers
• reducing erosion in flash tank caps, and
• disrupting an erosive vortex in a PD pump accumulator

If you’re interested in minimising the impact of slurry erosion – and your equipment replacement costs – through the development of preventative solutions, we are uniquely positioned to assist with your operation and add value to your project.

Contact the team on +61 3 9545 8865 or email me, Mark.Cooksey@csiro.au, to discuss how our expertise and experience can help you.

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