Defeat the Destruction: The Top Five Application Areas
By Barry Nisill, Belzona Canada
Inside Mining: Belzona’s Top 5 Application Areas
Explosions, drilling, crushing and digging. 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. Each mine or quarry will suffer from a unique array of threats as a consequence of their processing steps.
Having developed solutions for mining applications since the 1950s, Belzona has a vast amount of experience in understanding the effects of the mining processes on machinery and equipment, and where the most amount of damage develops. As a result, we have put together a list of what we believe are Belzona’s ‘Top 5’ most common application areas within this industry. These include:
- Repair of rubber components
- In-situ repair of damaged and scored shafts
- Lining chutes, hoppers and pipework
- Repair and protection of pumps
- Shimming of machinery and equipment
During this article each one will be examined in turn to understand the key reasons behind why these areas pose perennial problems.
Repair of rubber components
First on our list is the repair of damaged rubber components and equipment. This type of problem is regularly associated with conveyor belts and off-road tyres, 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 rubber material, tearing and splitting the conveyor belt. Similarly, the off-road tyres of large trucks, diggers and earthmovers are subject to hostile conditions with immense stress being placed upon tyre sidewalls, shoulders and crowns. Notably these areas can be damaged due to the effects of long lengths in service, impact, incorrect inflation or simply because of rocks, causing splits in the rubber.
The most traditional rubber repair technique within the industry is vulcanisation, which comprises of 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 the state of the equipment. Furthermore, vulcanisation requires time for a specialised vulcanising crew and equipment to be brought on site, necessitating long shutdowns. These shutdowns can be costly and inefficient, especially when heavy industrial belts are capable of moving over 5,500m3 (194,231ft3) per hour, when fully loaded. That’s enough to fill an Olympic swimming pool in just less than 30 minutes!
Cold-cure resins offer an alternative and distinctly different solution, as they can be applied in situ without specialist tools, thus eliminating the need for hot repair processes. Moreover, they offer a versatile repair where durability and elasticity, as well as good abrasion and tear resistance, are required.
In-situ repair of damaged and scored shafts
Our second application area concerns damage that can occur to shafts. In this instance, machine and equipment shafts are susceptible to routine damage from the effects of erosion and corrosion, which can cause mining process delays and severe downtime. Damage to shafts usually occurs at bearing locations, journal and seal areas due to wear. Generally, the erosion and abrasion can be attributed to vibration, wear and lubrication-loss, all of which can lead to scoring, distortion and misalignment.
Aside from replacement of 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. Instead, some utilize orbital welding, that operates 360o 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.
Lining chutes, hoppers and pipework
As you may have guessed, 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 and impact.
In terms of the repairs available for these types of equipment, they are two-fold – protection and prevention. 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.
Repair and protection of pumps
Pumps are used throughout the mining industry for a melange of processes, 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.
Shimming of machinery and equipment
Finally, at number five is the creation of shims. 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. Additionally, equipment size can differ from OEM specifications to in-service, resulting in loose components which can be damaged or totally removed by impact and vibrations present throughout industry processes. 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% 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.
About the Author
Barry Nisill is Vice-President of Belzona Canada, and has been with Belzona for 11 years. He is a qualified mechanical engineer and brings his technical skills and attributes together with his commercial knowledge to assist in growing the business. Belzona Canada opened in 2009, offering localized supply of materials, training to perform a reliable long-term repair, application supervision or a full supply and apply to Canada. Learn more at www.belzona.com.