In 1986 Osborn supplied two 14’ x 22’ shell-supported ball mills for a gold project located in Stilfontein, South Africa. The plant was shut in 2012 and NCP purchased the mills in 2017 together with a three-stage crushing circuit.

In 2019, NCP was awarded the contract for the supply of two 14’ x 22’ refurbished shell-supported ball mills for a client in Northern Zimbabwe. Based on the client requirements and the redundant stock NCP had available, an agreement was reached to supply the mine with re-engineered and refurbished mill components.

NCP’s scope of supply included the MV switchgear together with liquid resistance starters and mill main motors. Several upgrades were completed including:

  • Changes to the ratio of the main reducers to increase the speed of the mill and allow increased power draw within the design limitations of the existing drive train.
  • Manufacturing new discharge endplates for a heavier cantilevered load required for the new trommel screen.
  • Changing the liner design from a grate discharge to an overflow discharge arrangement.

On completion of the mill refurbishment, NCP transported the mill components from Johannesburg, South Africa to the mine in Northern Zimbabwe. NCP’s installation team were on site to supervise and assist with the installation and upskill of the local labour, teaching them the necessary skills required for mill installation and maintenance.

The re-engineered and refurbished components completed under NCP’s quality control allowed us to provide a warrantee equivalent to that of new equipment.

The mills were successfully commissioned in 2021, completing the entire design, manufacture, delivery and installation cycle. The mills are operating successfully with full after-sales, technical support, and regular maintenance inspections being undertaken by NCP.