MINING equipment and infrastructure in any industry are often subjected to the harshest environmental factors, such as heat, constant impact, abrasion, corrosion and chemical attack.
Surface coating technology is making great headway toward protecting this valuable equipment and prolonging service life.
After 26 years in the protective coatings industry, Queensland manufacturer, LiquiMix, has developed a range of polyureas that solve many expensive and environmentally sensitive problems facing the mining industry.
LiquiMix’s range of Tufflon polyureas contain varying degrees of hardness, impact resistance and flexibility, with added qualities of anti-static, fire-resistance, extra-slip and potable-water approval.
All-rounder Tufflon-P80, a polyurea coating designed for permanent immersion (and complies with AS4020 for potable water) is ideal for lining chemical bunds and for use over geofabric to provide a flexible repair of damaged concrete and dams. Tufflon-P80 has an elongation of 450pc pairing strength with great flexibility.
The elastomeric properties of Tufflon allow for thermal expansion and contraction of the concrete or steel substrate underneath, without tearing or splitting, bridging hairline cracks and providing permanent protection.
Coal wash plants are a highly abrasive environment where Tufflon-P80 shines; it is three times more abrasion-resistant than steel and has proven very successful as a lining for inside coal wash down chutes.
Conveyor pulleys are prone to rapid wear from dust and contaminants and are also highly resonant and noisy during operation, if insufficiently lagged.
Because Tufflon-P80 has excellent adhesion to steel, when it is applied to these pulleys they wear significantly less, have longer service intervals and operate far more quietly.
The anti-static grade Tufflon-P90AS prevents even more coal and iron ore dust from clinging to the pulley, reducing wear even further.
Tufflon-D60 is harder than P80 and was developed for application directly to steel without a primer, however best results are achieved when the surface is blasted first, in preparation.
Exceptional impact resistance is D60’s star selling point, as it can withstand the constant pounding of the ore.
This coating finds extensive use in the trays of mining tipper trucks and has been widely accepted by the Australian Transport Authority because of its unique characteristics.
Variant Tufflon-D60SL has an extra slip additive allowing for loads to release more easily and at a lower angle than an uncoated tray.
Typically, D60SL allows a load of material to release 20 degrees earlier than an uncoated tray surface.
Thus, if a load would normally begin to slide at 45 degrees, the Tufflon-D60SL coating would allow it to release at only 25 degrees.
As a result, the tipper tray is lower when the load begins to move, which is safer for personnel and less likely to cause the truck or trailer to tip on an uneven or soft surface.
Tufflon-D60 is particularly useful in aluminium trays. Aluminium construction helps to reduce GVM and therefore increase the vehicle’s actual payload, but the alloy is notoriously wear-prone and suffers greatly from the continuous impact and abrasions or coal and ore.
D60 or D60SL can be applied at a thickness of only 3mm at the front end and on the sides of the tray and gradually increased to a thickness of 8mm at the rear of the tipper, where the greatest abrasion occurs.
Tufflon-D60 and D60SL have excellent impact resistance but also superb adhesion to all metal. In the case of aluminium though, the surface should be blasted and etch-primed before the D60 top coat is applied.
LiquiMix tests all applications for adhesion, using a hydraulic adhesion tester.
Hydraulic force is applied to the lining until the Tufflon is eventually pulled away from its substrate.
The force required to break it away is measured and recorded. Forces of 5Mpa (725psi) have been required to pull Tufflon off aluminium and as much as 12Mpa (1740psi) have been required to tear it off a steel substrate. This is a significantly high level of adhesion.
It is this level of bonding between Tufflon and a variety of substrates that makes it suitable for coating steel pylons before they are driven into the ground, to prevent corrosion.
It is also used extensively on offshore rigs for corrosion protection of metal infrastructure and equipment at sea.
Both P80 and D60 can be applied to concrete to form a seamless coating suitable for containing everything from potable water through to the harshest acids and alkalis.
However, fast-curing epoxy primer Civilox is required before either coating is applied to bare concrete to avoid pinholes in the finish.
Application of P80 and D60 polyureas are done with specialised plural spray equipment that accurately proportions the two parts, pressurises and heats them and then mixes them at the gun.
This airless spray system is produced by Graco. LiquiMix is the leading Graco Reactor distributor throughout Australia and New Zealand and has the largest Graco service centre in the southern hemisphere.
Another product earning its stripes in the Australian mining industry is Liquibond, a unique single-part polyurethane that binds the surface of gravel roads or compacted road base.
Liquibond can be applied by spraying or dribbling it over the road, at which point it penetrates the top 50mm below the surface providing long-term consolidation and very effective dust control.
Heat, dust, salt, abrasion, water and noxious chemicals constantly take their toll on mining equipment and infrastructure but LiquiMix’s range of polyurea coatings are cost-effective and create long-term savings over the life of the mine.
They work hard and extend maintenance service intervals, increase component service life, improve tipper safety and protect expensive fixed plant equipment.
Tufflon coatings may not bask in the limelight but they are definitely film stars.
