Kinross Fort Knox Conveyor Bent #1 Repairs
Kinross Gold Corporation determined that repairs were needed to a set of previously damaged supports of Conveyor #1. This operation transfers the mined ore to another conveyance system that feeds into the mill that extracts the gold. This function is vital to the financial health of the entire mining operation at Fort Knox.
Damaged by a combination of past earthquakes and operations, Bent #14 located at the conveyance/stockpile end of the 2500-foot long overland Conveyor #1 had been partially repaired in the past. After careful inspection, the client and Morrsion-Maierle’s engineering team determined that it required complete replacement to be safe during all potential loading events, including potential earthquakes and wind storms.
• Unforgiving time constraints for both construction and design, requiring construction during the first season’s conveyor downtime to be a double shift, 24/7 operations for a 10-day period where both the construction and engineering/inspection team were pushed to their limits.
• This project required detailed site/structural investigations of existing construction to determine the existing conveyor truss’ condition and as-constructed nature in order to evaluate how to reinforce it for new load paths.
• Developed design and construction approaches that dealt with the fact that the existing conveyor was deflected on the order of multiple feet in both the longitudinal and transverse directions, requiring detailed field measurements and adjustable connections to allow for field fit-up.
• Detailed, finite, element-analysis modeling and complicated conveyance/operational and environmental/structural loading conditions to accurately determine reinforcing requirements.
• Designed and constructed the large foundation supports (30’ square x 3 foot thick footings, 14’ wide x 12 deep x 29 foot high piers) that required “mass concrete” considerations such as special mix design and placement methodologies.
• Designed and constructed 42” to 60” large diameter structural steel tubes that had lengths up to 140 feet.
• At the tops of the new steel tube supports, connection pieces needed to be designed and constructed that would allow for a “pinned” connection at the conveyor truss support yet be a rigid enough connection to transfer all the vertical and lateral load into the supports. Additionally, these heavy elements needed to be in place and carried by the existing conveyor truss and existing supports prior to the new supports being installed, requiring a detailed analysis of these existing members/elements.
• The management of conveyor operations and construction sequencing/phasing of the work to keep loading on the existing damaged supports from not exceeding what could be reasonably understood to have been carried in the past.
• Developed a methodology for jacking the new supports into place to preload them with the existing dead weight of the conveyor to allow the existing supports be under less load during their removal.
• During construction, the team worked around unpredictable weather in the mountains north of Fairbanks, Alaska.