Advanced Coating Technology Boosts Productivity And Safety For Annual Maintenance Program 

By: Dave Maurer, Marketing Manager, North America
    

Each year, engineering and maintenance teams at the Mosaic Potash Colonsay mine, located in the Canadian province of Saskatchewan, perform a routine assessment of the mine’s 225-foot cold slime thickener tank and other equipment assets.

The sprawling Colonsay facility is one of three Mosaic potash mines, producing 1.8 million tons of the valuable mineral each year. The cold slime thickener tank processes the chunks of rocky clay retrieved each day using salt brine and other chemicals to extract the potash. Keeping production yields on track is critical, making yearly maintenance inspections of the tank an important, yet potentially costly process.



The late June 2009 inspection was going smoothly until the Mosaic team and long time maintenance contractor, Wayne Danger of Danger Sandblasting & Paint in Shellbrook, SK, detected gaps around the tank’s steel welds and other signs of corrosion. The existing coatings totaled 40 mils and consisted of various coal tar products, neoprene, and an International Paint Protective Coatings product.

“The initial plan was to re-apply the International Paint product over the aged coatings,” said Danger. “But after a quick brush blasting, it was clear that the coating integrity and inter-coat adhesion was less than acceptable, requiring a complete removal of the tank’s linings.”

International Paint Protective Coatings had applied the coating in 1969, so Mosaic’s Mill Maintenance Engineer, Matthew Mireau, consulted with account executive, Chad Milbrandt.

“Interzone 954 was still viable for the tank’s rake and drivers after repairs, but Mosaic needed a lining with exceptional adhesion qualities and ultra-fast cure rate to minimize downtime,” said Milbrandt. “More importantly, Matthew was concerned about the danger of flash points and other safety issues associated with solvent-based tank linings.”

Milbrandt recommended a 100% solids, high-build epoxy novalac tank lining solution from International Paint’s Enviroline product offering. One high-build coat provides excellent immersion protection and durability, in addition to lower application costs and quick turnaround.

With a green light from Mosaic, a crew of eight began removal of the existing coatings, sandblasting tank walls to a NACE No. 1/SSPC SP-5 white metal finish. But after sandblasting, crews were immediately faced with the problem of flash rusting caused by high humidity inside the tank. Crews re-blasted 100-foot sections of the tank at a time, then spray-applied a high solids, low-VOC, rust-inhibitive epoxy polyamide primer, followed by the application of a high performance epoxy novalac lining to an average dry film thickness of 32.5 mils. A highly flexible chemical-resistant epoxy novalac polysulphide was then troweled onto the tank’s connecting seam where the floor and wall meet. The lining system was completely cured within two days, allowing the tank to be re-filled with the salt brine mixture.

“The International Paint Enviroline system prevented unnecessary delays to the re-coating installation, which helped put us back in production and meet our deadline,” said Mireau. “Coating technology can play a huge role in helping provide higher safety standards, faster turnaround and streamlined costs to our ongoing maintenance program.”
 

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