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Uranium is a very dense metal that is often used for nuclear energy across the globe.  It is mined with leaching tanks that separate the element from ore and then pump it to the surface.  Two large uranium processing plants, Ranger (in Northern Australia) and Rossing (in Namibia), have been mining uranium for decades, but recent leaks due to faulty tank lining and tank corrosion have caused many problems.

 

This past December, the Ranger uranium-processing plant in Australia spilled more than 1 million liters of liquefied uranium from a 3-story steel leaching tank.  The leak is being blamed on a faulty tank lining; damage to the rubber liner caused severe wall corrosion of the steel tank. The spill at Ranger was the second in a week-long period for controlling operations company Rio Tinto; only a few days prior, a similar leak occurred in Rio Tinto’s Rossing mine in Namibia. 
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View of the collapsed leaching tank
Credit: NT News

 

At the Ranger site, a 1450-cubic-meter leaching tank developed a hole because of the massive wall corrosion, and then split and fell, knocking over a crane in the process. After the collapse, Ranger’s tanks were all inspected; one of the six tanks was found to have steel corrosion similar to the one that collapsed.  The spill has been blamed on a combination of metal and management failure, but considering the age of the mine, experts are warning of continuing uncontrolled and unpredicted equipment failures.  All of the mine’s pipes, pumps, and tanks are over 30 years old, past its full design life. 
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Ruptured leaching tank wall
Credit: The Chronicle

 

Corrosion is an issue for steel tank owners everywhere. It’s not a matter of if, but when. Fortunately, problems like those experienced at the Ranger and Rossing mines can be prevented with HJ3’s CarbonSeal carbon fiber.  Recently, a geothermal power plant with severe corrosion on its primary clarifier and demister tanks was repaired with HJ3’s CarbonSeal reinforcement system.  The clarifier, which is 43’ high and has a diameter of 125’, had approximately 80{f00316eaeff19fc4d3daa6454136ee4db9a0ad1868aa2a79e58a2db09827821d} steel loss on its sidewalls, upper tank ring, and dome due to corrosion. The corrosion had weakened the structural integrity of the tank, which required reinforcement and protection against future deterioration. The exterior temperature of the sidewalls was approximately 140°F. The demister vessels had experienced major steel corrosion on the sidewalls of the upper tank rings and the dome of the tanks. There was an estimated 90{f00316eaeff19fc4d3daa6454136ee4db9a0ad1868aa2a79e58a2db09827821d} steel loss. The vessels required strengthening to the upper tank ring, domes and shell walls.
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Geothermal power plant primary clarifier wrapped with HJ3’s CarbonSeal system

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Installers apply HJ3’s CarbonSeal system on the tank shell
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HJ3 installers
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Close-up of CarbonSeal carbon fiber
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Geothermal power plant primary clarifier with HJ3’s CarbonSeal system

 

Four areas were scheduled for repair on the clarifier: a wall patch, the tank sidewall and dome roof connection, dome roof and a 36″ diameter overflow pipe. The steel was scraped with an abrasive blast and primed. A high modulus paste was applied, and the CarbonSeal carbon fiber was then saturated and installed. A chemical-resistant topcoat was applied, protecting the system. The CarbonSeal repair adequately provided the 20-psi required hoop strengthening to the steel vessel. To date, HJ3 has strengthened four clarifiers, two demisters, and one rock muffler for a client, who has saved 80{f00316eaeff19fc4d3daa6454136ee4db9a0ad1868aa2a79e58a2db09827821d} on the cost of replacing the components.  Additionally, the client was able to save on environmental costs, as 602 tons of steel were prevented from potentially going to landfills, and 1183 tons in C02 emissions and 36,000,000 gallons of water consumption was prevented as the manufacturing of new steel tanks was not required. If you have a steel tank that requires reinforcement or repair and would like to learn more about HJ3’s CarbonSeal reinforcement systems, contact HJ3 at info@hj3.com.