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Mopani Copper Zambia: Nkana Copper Concentrator Automatic Lubrication Solution

The Glencore Mining company operates a Copper Mine (Mopani Copper) in Kitwe, Zambia and utilise an 18x ball mill copper concentrator facility to process the copper ore into copper concentrate. Each mill carries a 60-ton charge of copper ore and water and rotates on large bearing housed units, equipped with Timken 239/900KYMB spherical bearings (900mm bore and 1180mm OD). Timken makes regular sales and service calls to this mine and supply a multitude of bearing products.

Problem Statement

Regular bearing failures on the ball mills were occurring due to high amounts of copper slurry contamination ingress through the labyrinth seal arrangement. The cost associated with bearing replacement and the maintenance required for this replacement, combined with the loss of copper concentrate production, was unsustainable for the Mopani mine.

Groeneveld Recommendation

Timken recognised the opportunity to provide a Groeneveld Solution. Timken & Groeneveld concluded a joint visit to the mine and presented an option of installing Groeneveld lubrication systems to the mill sets to allow for constant charging of the large labyrinth seals with clean grease, thereby ensuring no ingress of slurry. The greasing systems would also ensure the bearings are constantly supplied with clean grease, at the right volumes.

The Groeneveld Solution

  • 9 x complete lubrication systems: 9 x 18 kg Twin barrel pumps with #11 metering units
  • Quick couplers fitted on all points: 14 Points per mill set -
  • 126 Lubrication Points
  • 800 m of grease lines
  • 9x greasing system cabinets
  • 800 m of lines trunking and fabrication
  • Preventative maintenance procedures, documentation,
  • maintenance personnel training sessions.

The Twin barrel pump was selected due to its storage capacity and robust design. As the pump would supply a mill set, which meant 2 single mill drums. Each mill was supplied with its own output line and metering block.

Due to the aggressive purging required for the labyrinth seals and the physical size of the seals and the bearings, the grease volume was eventually set to around 5kg per 24-hour cycle.

To ensure a clean and secure environment for the pump and electrical connections, the units were installed in sealed, steel cabinets. The fabrication and laying of the trunking was then placed accordingly.

After installation and commissioning of the system, the concentrators production team was trained in the monitoring and use of the units and the maintenance personnel trained in the monitoring, maintenance and refilling of the reservoirs.

Current Operational Status

Currently the system is operational, and the customer is extremely satisfied with the reliability and consistency of grease supply. The vastly improved greasing cycles are evident during Bearing Preventative Maintenance procedures, during which the cleanliness of the grease within the housing interior is evident. Improvement in bearing wear rates are already evident in the reduction of RIC growth trends.

The Mopani Mine and Groeneveld partnership has evolved and grown since commissioning to now include a maintenance contract, which pays for a full time Arrow (Timken Distributor) / Groeneveld technician, who performs preventative maintenance activities on the Groeneveld systems. The preventative maintenance activities include physical system maintenance, Gina download and reviews, reservoir refill and submission of traceable PM documentation to the mine maintenance planners for recording.

Next Steps

Further developments will include the proposal for bulk Groeneveld grease supply to the concentrator (17 tons annually) and the maintenance of the bulk grease stocking requirements. Opportunity exists for open greasing systems, R&D required around application of grease onto the gear face.

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