Processing

Extending the life of plant assets

Unlike the mining industry, which extracts and processes products that can sell between $250 and $1000 per cubic metre (m3), the quarry industry does not have this luxury, but still requires the use of similar high cost capital equipment.

This expensive equipment is used to extract, crush and shape a quarry’s finished products for well below $50/m3, which is a fraction of the mining industry’s price (ignoring margins). With this in mind, quarries predominantly supply the construction and road building/repairing markets, which are competitive industries that can keep the crushed rock aggregate $/m3 down.

Australian quarry environments present some of the most extreme working conditions known, with expensive equipment enduring high wear rates, significant abrasion, extensive corrosion/erosion, extreme temperature variations and repeated high impact to materials transfer and load bearing platforms.

Quarries are hard-pressed to get the most out of their assets while increasing efficiency and reducing running costs. However, overworking equipment can lead to premature failure of expensive assets, which can in turn increase cost and result in lost production.

Finding solutions to prolong maintenance intervals and extend asset life is a major focus for all industries, and particularly for quarries, due to the high capital investment cost versus low $/m3 return rates. Increasing the wear resistance of critical components and the ability to perform fast and cost-effective repairs to high wearing zones, parts, structures and foundations is absolutely crucial in reducing equipment downtime.

WRP COMPOSITES

Advanced polymer composites should include various sized ceramic beads or fibres, silicon carbide or modified rubber particles, plus superior adhesion properties in the formulation matrix. Matching the correct product and application at hand is also critical to achieve optimal results.

Wear resistant polymer (WRP) composites offer superior wear resistance to sliding abrasion and have better adhesion qualities when applied to correctly prepared surfaces, lasting significantly longer than the original surface due to their high wear resistant formulations. WRP composites also protect against corrosion while increasing the life of assets. Dry versus wet applications such as dust chutes or water pumps require significant attention to detail. They should also be easy to apply via brush or trowel methods.

SURFACE ENGINEERING SOLUTIONS

Loctite’s superior and well-known Nordbak and Fixmaster brands of WRP composites can help rebuild, repair and protect, with formulations that are application-specific. By combining our product knowledge and quarry-related experience we have delivered major improvements in Loctite’s high wear rate problem areas:

• Chutes, hoppers and elbows.
• Pug mills and cyclones.
• Vibrating screens and feeders.
• Pumps, volutes and impellers.
• Grouting foundations.

TRANSFER CHUTE – RAPID WEAR RATE

At a large Victorian quarry, the -14mm to +7mm aggregate flow discharging from a Jaques torrent screen onto the transfer chute was rapidly wearing away on the inside front face and corners, eating away at the chute’s structural integrity.

This wear/abrasion was most likely caused by an excessive velocity increase linked with a 25 per cent increase in throughput over the original design capability. As well as this, corrosion/erosion was accelerating wear due to the hard water used in the dust suppression spray system. Over many years the quarry manager had trialled ceramic tiles and special hardened steel plates but both had failed, stemming from either tile to chute adhesive failure and weld failure of the chute to steel plates.

The quarry manager was keen to try the Nordbak high impact wearing compound, after learning it was an easy trowel-on, two-part fine ceramic and rubber modified epoxy with impact resistance superior to ceramic tiles and an impressive
adhesive strength.

With Loctite supervision the site maintenance crew cleaned the surface using a high pressure wash gun loaded with Loctite Natural Blue (non-flammable and environmentally friendly) cleaner and degreaser.

The surface was than roughened using 100 grit flexi-abrasive wheels. Immediately after this, to avoid any flash off rusting, the surface was painted with a base coat of Loctite brushable ceramic, achieving a 0.5mm super adhesive epoxy finish.

Once tacked off, two 6mm top coats of the high impact wearing compound were applied to achieve the desired 12mm thickness.

The results were monitored over a six-month period, recording an exceptional outcome, with the compound outperforming the ceramic tiles and welded plates twofold. One year later this quarry site is still using the product, with recoats applied every two to three months.

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Vaughan Bartleson is Loctite’s Victorian-based key account manager for quarries, mining and power.

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