Polymeric Repair Composites in the Mining Industry

Polymeric Repair Composites in the Mining Industry

Written by Jamie Hutchinson, Marketing Executive at Belzona

The mining and quarrying industry brings together some of the most destructive forces affecting modern day machinery and equipment.  The threats associated with the mining environment can vary, often introducing a combination of abrasion, corrosion, wear, impact, and chemical attack.  Significantly, the type of damage that can occur is completely dependent on the type of mine, or quarry, whether these are afflictions specific to location, or the type of material being excavated. 

One of the most common problems in the mining industry is damaged rubber components and equipment.  This type of problem is regularly associated with conveyor belts, which can be torn, ripped and split.  Primarily, conveyor belts are exposed to excessive wear as a result of the materials they transport and the friction generated from the rough sliding and impact of these hard materials.  As part of their design, the equipment surfaces are expected to absorb some of the energy this impact, yet jagged and sharp material can still penetrate the material, tearing and splitting the conveyor belt. 

The most traditional rubber repair technique within the industry is vulcanisation.  This comprises heat and pressure being applied to rubber components, creating a strong chemical bond.  Whilst this does offer a long-lasting repair, the process too frequently relies on very specific environmental conditions and equipment.

Rapid-curing elastomeric materials like Belzona 2311 (SR Elastomer) offer an alternative solution.  They can be applied in situ without specialist tools, eliminating the need for hot work.  They offer a versatile repair where durability and elasticity, as well as good abrasion and tear resistance, are required.  Rapid cure times also ensure that emergency repairs can be carried out, keeping downtime to an absolute minimum.

• 

• 

Shafts are also a common area for damage in the mining industry.  Machine and equipment shafts are susceptible to routine damage from the effects of erosion, corrosion and abrasion, as well as mechanical damage due to the failure of bearings, which can cause mining process delays and severe downtime.

Common practice might be to use welding as a repair method.  This hot work required can permanently damage the shaft. The repair would also require machining; often meaning these methods need to take place in a workshop.  This then requires the need for dismantlement, resulting in more downtime.  Aside from also entirely replacing the worn shaft, which is very expensive and time-consuming, shafts can easily be rebuilt to recover their original surface profile.  There are many solutions available to the mining industry which requires dismantling the equipment to remove the shaft.  However, this creates excessive downtime periods which are expensive and unnecessary.  Some instead utilise orbital welding, that operates 360 degrees around the shaft, welding to the static workpiece in a continuous motion. Fundamentally, these once again can require a great amount of equipment being brought to site, increasing downtime and potential hazards.

Conversely, cold-applied, metal repair, polymeric composites are available to restore shafts in situ to their original dimensions.  Once cured, these materials provide erosion and corrosion protection; in some instances, their self-lubricating properties help to safeguard against vibration and wear.  In addition, these composite repairs offer very high compressive strength, being able to cope with significant loadings.  Solutions such as Belzona 1111 (Super Metal) and Belzona 1131 (Bearing Metal) offer these performance benefits over traditional methods.

• 

• 

Chutes and hoppers are amongst the most heavily threatened pieces of equipment in the industry.  Much like conveyor belts, solid handling equipment is exposed to extensive erosion and abrasion from excavated materials of varying sizes.  Not only that, but the impact, trajectory and volume with which some of the material is transported through the chutes and hoppers can have detrimental effects on their structure.  This can often leave equipment affected by cracks, holes and wall thickness loss as a result of the intense abrasion, erosion, corrosion, impact and sliding abrasion.

Initially, in order to return chutes and hoppers and other such apparatus back to service, it is necessary to fix holes and cracks.  Historically, this has been done using hot-work to weld metal plates into place over the defect; however, this is being matched by the advent of cold-bonding practices which allow metal plates to be bonded onto the equipment using cold-curing, polymeric materials.

Once the repair has been completed, providing protection of the main impact zones is crucial to preventing further damage.  This can be achieved by an array of sacrificial barriers or linings, which help to absorb impact and abrasion from the mining materials.  More recently, ceramic-filled abrasion resistant linings have become common place in order to protect chutes, hoppers and pipework.  Solvent-free and cold-curing, these linings can be applied in situ without the need of specialist tools, which allows for safe and easy applications in confined spaces.

• 

• 

• 

Pumps are used throughout the mining industry from the transport of slurry, to the pumping of subsoil water.  As these materials are pumped along through the process chain, they each carry with them a variety of problems, threatening the service condition of the equipment.  The consequence: abrasion and erosion-corrosion damage, as well as chemical attack, occurring on main pump components such as impellers, casings and shafts.  Initially, this damage will lead to rough and pitted surfaces, which will increase friction and lead to a drop in the efficiency of the system as well as increased running costs. However, if not tackled in time, erosion-corrosion and abrasion problems may jeopardise the integrity of the component, ultimately causing failure of the equipment.

While replacement of the damaged components might be an obvious solution, it is usually associated with high costs and lead times of weeks or even months.  Hot work including welding and weld overlay, on the other hand, can induce heat stresses into the equipment and create problems with galvanic corrosion.  More importantly, however, neither solution will address the underlying problem.  For this reason, an increasing number of pump operators are turning to cold-curing polymer technologies to repair and protect their equipment.

• 

• 

Finally, due to the severe impact and vibration within the mining and quarrying industry, misalignment of machinery and equipment can occur quite frequently.  These shifts in alignment can lead to potential losses in efficiency and damage of the equipment, particularly in relation to bearing pin and bush housings and incorrectly fitting components.  Typically, shimming applications can be carried out in these instances, often associated with bearings, housings and foundations or bases.

Used to either align components and foundations, or fill gaps (irregular shims), shims can be created using many types of material, including metals.  However, in order to provide 100 per cent contact and avoid future damage, shimming can be completed using polymer composites.  In the mining industry in particular, surfaces are often uneven or difficult to access without dismantling equipment, therefore fluid shimming materials can be poured or injected around irregular components, before curing to ensure maximum support.  Overall, shims borne from polymer composites can be customised to each specific application, dependent on size and shape, whilst retaining excellent load-bearing strength. Solutions like Belzona 7111 offer the ideal chocking/shimming solution by simply pouring the material to flow, contour cure around any irregular surfaces.  Once cured, the polymeric composite provides pressure, impact and vibration resistance against heavy machinery. 

Having developed solutions for mining and quarrying applications since the 1950s, Belzona has a vast amount of experience in understanding the effects of the mining processes on machinery and equipment.  Especially, where the most amount of damage develops, and not only how to repair such damage, but to also ensure long-term protection to those areas.  Polymeric repair composites and coatings offer several benefits over traditional repair methods, both from a performance and application perspective.  Using such technology also eliminates the need for expensive replacements, keeping downtime to a minimum.  Belzona provides a truly global service, supplying repair and refurbishment services, as well as offering local application training to allow for maintenance teams within mines to carry out their own specialized work.