Many people think that mine closure work comes at the end of a mine’s life—when operations end. But, sometimes mines need to close parts of a site during its operating life. This kind of closure is called progressive closure.
Last year, U.S. Borax completed the progressive closure of part of our processing plant at Boron Operations. Careful planning and the use of 3D imaging technology made the work safer and created valuable space.
Space to unlock new value
The seven-story-high structure, made from 900 tons of steel, dated back to the 1950s and was used to dissolve ore from the mine. It was decommissioned in 2014 when we built our Modified Direct Dissolving of Kernite (MDDK) Plant. It took four months to safely demolish the structure, but Brett Wilson, Engineering Manager at Boron said the team started planning demolition six years before work began.
“Taking our time to strategically plan exactly how we could best carry out the demolition of the dissolving structure with respect to safety, cost, and our ongoing and future operational needs, was key to such a successful outcome. We took the time to thoroughly scope the project, and allocated our own people to focus on this work.
“Removing the structure also removed a potential risk to our people,” adds Brett. “And, we no longer need to do frequent structural assessments of the old structure to keep our people safe on site.”
3D modeling for safety
We used innovative 3D modeling and animation to do virtual walk-throughs of the plant, to help understand and plan the demolition sequence, and to do a detailed risk assessment.
“Along with the 3D modeling, we also leaned on learnings from other demolition work undertaken at other Rio Tinto sites, such as Resolution Copper, to integrate different techniques proven to deliver results.
“For example, we learned not to follow what is often a common practice in demolition: To pile the material and use it as a ramp for machinery to drive on to reach different aspects. Experience showed this proved a higher safety risk, and was eliminated from our process. We also fitted our excavators with ballistic strength glass, to further protect our workers.”
The project was completed safely without incident or lost work time injury. While we don’t yet have firm plans for the area that has been cleared, when the plant is ready to expand, we have immediate, safe access to this useable space.