Emergency gearbox repair at African gold mine

Stork gears & services was invited by a gold mining producing company, located in mali and operating the kalana gold mine.

The mine exists of two mine shaft conveyance systems for handling production, personnel and material. Following a routine inspection of the No. 2 Shaft winder gearbox, our customer noticed severe pitting and cracks at the intermediate pinion shaft. It was decided to invite a diagnostic engineer from Stork Gears & Services in order to determine the root cause failure of the damage and discuss repair possibilities. 

A design calculation of the gearbox was also requested by the customer in order to determine whether the gearbox is actually rated for the duty or not. Our engineering department has measured all dimensions which allows us to reproduce a complete new internal gear set. The design calculation will point out if new stronger gears are necessary and if the ore production could be increased.

Following the examination of the gearbox by our engineer it was decided to suspend production and dismantle the gearbox. The damaged pinion shaft was immediately transported to Rotterdam by plane. Shaft No. 1 continued to be fully operational providing access to the mine. Ore production and development was also continued but was constrained by the surge capacity in the mine. The gearbox itself was also airfreighted to Rotterdam for complete testing and reassembling.

Challenge

Week 1

• Visual inspection of the gearbox and shaft
• Onsite non destructive cracks examination testing
• Dismantling of the gearbox
• Transport of the damaged shaft by plane

 Week 2

• Transport of the gearbox by airplane to Rotterdam
• Manufacturing of a new pinion shaft in our workshop

 Week 3

• Machining of bores of the gearbox casing
• Regrinding of teeth of the output shaft
• Transport back to Africa

 Week 4

• On-site re-installation of the gearbox
• Alignment from motor to gearbox
• Vibration measurements
• Complete test run

Gold mining in mali

Mining has long been an important aspect of the Malian economy. At the end of the 20th century Mali had the third highest gold production in Africa. The former Soviet Union had been a major source of economic aid, including construction of the Kalana gold mine.

Market segment: Mining