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Monday, September 13, 2010 |
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Structural Rehabilitation Work for Gold Mines in Africa
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Source: Leon van der Merwe
Geita Mine – Northern Tanzania
Client Anglo Gold Ashanti approached the Stefanutti Stocks structural rehabilitation section to assist with remedial works to the supporting base of the primary crusher at Geita Mine in Northern Tanzania.
The primary crusher is a gyratory crusher installed in a typical primary tip/crusher arrangement. The supporting base of the gyratory crusher was showing signs of distress due to extreme stresses transferred from the crusher onto the base, and the lack of cover to the four 75mm holding down bolts.
We were approached as a contractor with skills and experience in this type of work, to repair the base as a number of cracks had developed. These were repaired by means of injecting a low viscousity epoxy resin into cracks. In addition to the crack repair a high strength reinforced grout skin was added to the outer face of the base.
Due to the remote location of the mine, the project required precise logistical and resource planning. The mine was shut down for five days to allow a five day, around the clock rehabilitation operation. Material and equipment was shipped in three months prior to the scheduled shutdown.
“Our team travelled for two days and took three flights to get to their final destination,” says Pieter du Plooy, site agent. “The project was a great success and the team is looking forward to their next African adventure.”
Syama Gold Mine - Mali
Client Somisa SA Syama Gold Mine has a similar mining operation to that at Geita Mine, and was faced with the same weakness in the concrete base of the primary crusher. Large cracks had developed and the engineers required an experienced contractor to assist with the repairs of these cracks to reinstate the integrity of the concrete base.
Additional structural problems on the base support included the spalling of the concrete around the outer face of the base, exposing the reinforcing. It was established that the direct stress transferred from the crusher steel base plate onto the top edge of the concrete base had caused the outer edge to fail and spall. The defective concrete was removed and the outer face repaired and re-profiled.
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