Palabora Copper Mine - Limpopo Province - South Africa

Sector: Mining

Procurement Type: Design Analysis

Owner: Palabora Mining Company

NOMA´s client: Palabora Mining Company

Design Period: 2013 – 2017

 

The Project

Palabora Mine is owned and operated by Palabora Mining Company (PMC) in Limpopo Province, South Africa. The Palabora Mine began as an open cut copper operation in 1964. Production commenced in 1966 at a rate of 30,000 t/day increasing to 82,000 t/day prior to closure in 2002. The final dimensions of the pit were 800m deep and 1650m to 1900m in diameter.

Underground block cave mining commenced in April 2001. The Lift 1 Undercut Level is located 1200 m below the surface and 420m below the pit floor. Upon breakthrough of the Lift 1 cave to the base of the open pit in 2004, significant instability in the north wall of the open pit occurred. The Lift 1 block cave has steadily produced 30,000 t/day and is expected to have exhausted the current resource in 2022. PMC is currently developing a second lift (Lift 2) to their existing block cave operation (Lift 1) to extend the life of the mine to 2033. Lift 2 is being constructed 450m below the existing Lift 1 infrastructure, at a depth 1650m.

The Lift 2 footprint is approximately 550m long x 250m wide for a hydraulic radius of approximately 85m. Cave propagation is commenced by advanced undercutting and the extraction level, located 18m below the undercut level has 17 production cross cuts for a total of 430 draw points. The coarse primary fragmentation of the cave material is dealt with two underground crusher chambers located approximately 80m offset from the cave footprint.

Key Aspects

• Offset herringbone layout extraction level.
• Advanced undercutting using an inclined ‘crinkle cut’ layout.
• Excavation and civil works for two crusher chambers at a depth of 1,650m below surface.
• Twin declines, man access and fixed conveyor, both 3.6km long to connect Lift 2 with the existing hoisting shaft..
• Two 6.2m diameter ventilation shafts, 1,200m long.

Scope of Works

NOMA Consulting was engage by Palabora Mining Company to carry out the following assessments:

• Back analyses of the Lift 1 block cave and North Wall open pit failure interaction.
• Cave propagation assessment for the proposed Lift 2 block cave.
• Assessment of undercut and extraction level performance during undercutting.
• Detailed ground support design and assessment of two proposed crusher chamber excavations.
• Assessment of Lift 2 block cave impact on North and South ventilation shafts.