OPERATIONS MANAGEMENT
form of corrosion protection provided as well. “If the ceramic shell and alloy layer is
ever breached, the ceramic shell acts as a reservoir of phosphate to continually realloy the steel,” explains Alpert. “Tis ‘self heals’ the breach, depending on its size, and stops the corrosion if necessary. Tis capability, along with the coating’s other properties, enables effective corrosion protection for the life of in-service structures with a single application.”
PREPARING FOR THE COATING To protect the steel hopper from corrosion, however, before applying the CBPC coating many years of iron ore deposits first had to be removed using mechanical hand tools, as some deposits were a few inches thick in places. Tis work had to be done far above ground, hanging from ropes, adding complexity to the project. Abrasive blasting was then done to
remove the remaining ore and surface corrosion. Since the steel hopper had never been painted and there was no visible mill scale, a surface preparation standard of NACE 3/SSPC-SP 6/SA2 was acceptable. One of the benefits of the CBPC coating, in fact, is a simplified surface preparation requirement, along with quick return to service that minimises facility downtime. Te time saved on an anti-corrosion coating project with the ceramic coating comes from easier surface preparation and expedited curing time.
CBPC coatings protect the large steel structures found at mines
With a typical industrial coating, near-white metal blast cleaning (NACE 2/ SSPC-SP 10/SA2.5) is required to prepare the surface. But with the ceramic coating, only a commercial blast cleaning (NACE 3/SSPC-SP 6/SA2 ) is typically necessary. A topcoat, if desired, can typically be applied within one hour of applying the CBPC primer due to its rapid drying and curing time.
When blasting was complete on the
hopper, the lower section was washed with potable water to remove blasting debris deep within the surface profile. Te steel hopper began to flash rust minutes afterward. Heavy surface pitting due to corrosion was also noted. However, unlike conventional coating systems, none of this was a problem for the anti-corrosion application. When the tank had dried sufficiently, EonCoat was applied directly to the
Application of the EonCoat coating on a mine hopper
steel surface without any further surface preparation. Te anti-corrosion coating was applied to the lower section of the steel hopper in a single coat at a thickness of 800 µm (800 microns or 0.8mm) over an eight hour shift. Te next morning the entire area was pressure washed to check if the application was successful. Unlike traditional coating systems that can hide future problems, the CBPC coating will simply wash off if it has not fully reacted with the substrate, allowing an applicator to touch up any problem areas before returning a steel structure to service. Over the whole area applied (4,090ft2 3ft2
gun. Due to the success of the project under tight time restrictions, the anti- corrosion coating has been approved for further projects throughout the mine. Since the coating is inorganic and non-toxic, there are no VOCs, no HAPs and no odour involved. Tis means that the water-soluble, non-flammable coating can be safely applied underground and in other confined spaces.
Although CBPC coatings are relatively
new in mine, quarry, and aggregate processing applications, their use will only grow as word spreads about how they can inhibit carbon steel hopper and structural corrosion for decades as well as reduce premature maintenance and replacement.
Hanging from ropes to conduct work adds to proejct complexity
22
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), only three small areas (less than ) were recoated, using a small cartridge
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