Palabora Copper Pty Ltd (PC) operates a mining and processing complex (Palabora Mining Company, or PMC) in the Limpopo Province of South Africa, near the town of Phalaborwa, approximately 500 km northeast of Johannesburg. The operations include an underground copper mine, a copper ore processing plant, a copper smelter and refinery, an open cut vermiculite mine and processing plant and a magnetite tailings recovery process.
The PMC mining operations commenced in 1965 by open cut mining methods, which transitioned to underground operations in 2003. It provides copper ore to the company's copper processing plant, smelting and refinery plants on site to produce copper rod and copper cathode sheet. Vermiculite ore is mined from a series of shallow open cuts and is upgraded through a processing plant to produce saleable vermiculite products. Magnetite is recovered from old tailings dumps and pumped to a magnetic separator for production of a magnetite concentrate.
The PMC underground copper mine employs a block caving mining method for the extraction of ore beneath the old open cut void. Production has been sourced from Lift I of the block cave from 500m below the floor of the open cut void. The Lift I block cave ore grade is in steady decline and was expected to become uneconomic by Q4 2015. However satisfactory ore grade has been achieved as the mine has continued to overdraw from the breakthrough into the previous open cut workings.
In 2011 PMC developed a plan to extend the life of the underground mine up to 2033 through the construction of a Lift II block cave 450 m beneath the current Lift I. In November 2013 the PC Board approved the project to complete the Lift II Feasibility Study (FS) and to continue development of the twin decline ramps and associated early works. Development of the declines to the prescribed schedule was an essential activity to maintain the viability of a second lift of block caving ore extraction for continuity of copper production at Palabora. The Lift II FS was completed in May 2014 and final project approval was obtained in December 2014. Lift I production will continue until the ore grade falls below economic cut-off and this is currently expected to continue until Lift II production is available.
The Lift II Project scope includes the following:
- Development of twin decline roadways to provide access to the Lift II orebody.
- A Conveyor Belt Decline and a Service Decline, extending beneath the current Lift I infrastructure, for access and materials handling.
- Development of vertical shafts for ventilation.
- Originally, two 6.1 m diameter, 1200 m deep Raisebored Ventilation Shafts connecting Lift II to the surface were proposed, but the design has now been amended to the blind sinking of one 8.5 m diameter, 1200 m deep shaft, because of poor ground conditions being encountered in the initial Raiseboring.
- Raisebored rises between the Lift I and Lift II levels will provide fresh and return airways for the Lift II development and block caving operations.
- Development of orebody footprint undercut level.
- Established 18 m above the extraction level. Access drives around the mining footprint and block cave undercut drill crosscuts.
- The mining sequence will be from NE to SW, utilizing a three-panel undercut sequence to limit the maximum undercut face length.
- Development of the ore production level.
- Extraction drives - dedicated personnel and production equipment tunnels around the footprint. The production level will also comprise the production crosscuts and draw point tunnels.
- An off-set herringbone pattern draw point layout, similar to Lift l will be utilized for Lift II, including tunnel and draw point spacing of 34 m x 17 m.
- Construction of all services and infrastructure to support both Lift II block cave development and steady state production.
- Crusher chambers and access drives development.
- Sumps and Pump Chamber.
- Crusher 5 and Crusher 6 complexes.
- CV 22 Conveyor leg.
- Ventilation Level.
- Access Ramps as well as associated large and vertical excavations.
- Ore flow infrastructure including conveyors and crushers.
- Two large jaw-gyratory crushers will be used to allow a larger material lump size and a better material reduction ratio for final product dimensions for conveying.
- High crusher availability is planned through maintaining critical spares on site and having a dedicated crusher workshop to facilitate maintenance and repairs independently from production.
- The twin crusher layout will be installed with eight independent tipping points and independent access points, based on experience obtained from Northparkes Mine in Australia for increased productivity.
The Lift II Project battery limits for the underground development and installations are defined as:
- Start of declines to the completion of Lift II footprint production and infrastructure development.
- Transfer feed point onto Lift I Conveyor 5, including the shortening of Conveyor 5.
Diesel Load-Haul-Dump units (LHDs) will be used during development and will continue for steady state production.
The surface works scope includes the following:
- Installation of two optical electromagnetic ore sorters prior to the Autogenous milling circuit.
- Upgrade of the Secondary Milling Plant (SMP) circuit in the existing Processing Plant by means of improved feed distribution to the mills, modifications to improve cyclone classification efficiencies and provision of particle size analyzing equipment to enable real time monitoring of milling performance (particle size distribution).
- Upgrade of the existing concentrator facilities by the installation of a new flotation circuit to maximize metallurgical performance.
The Lift II project battery limits for the Processing Plant upgrades are defined as follows:
- The start of feed conveyors to the Autogenous mills.
- The entry point of the new flotation circuits.
- Exit point of concentrate from new flotation circuits.
The study confirmed up to a 33,500 tpd Lift II design, 380 m below Lift I, with a mine life extension to 2033. Crusher 5 excavation
Surface Works - Underground
Ventilation Shaft - Blind Sinking
The blind sinking of a ventilation shaft project is underway and is expected to conclude in Q4 2023. Management advised that this is not expected to have any material impact on the ventilation capacity for completion of the Project, as changes have been made to the current ventilation system to ensure adequate ventilation is maintained until the new vent shaft is completed.
- Civils Works - Surface mining, terracing and high wall stabilization.
- Shaft Piling (to 45mBC) - Drilling of interlocking piles to curtain and stabilize collar.
- Shaft Collar Construction - Construction of collar and foundation for sinking headgear.
- Surface Infrastructure Establishment - Batch plant, winders, headgear, sinking ventilation, workshops etc.
- Shaft Pre-sink (4mBC to 60mBC) - Initial sinking to allow for the installation of the sinking stage.
- Slow Sink (60mBC to 204mBC) - To fully commission equipment and to bring the crew up to full efficiency.
- Main Sink (204mBC to 1190mBC) - Sinking and lining the shaft to 10m before holing with the airways.
- Drop Raising the Final Cut - Effective holing of the shaft into the airways.
- Shaft Stripping and Clearance - Removal of all sinking equipment for installation of permanent ventilation infrastructure.
Isometric View of The Mine
Lift II Project Achievements 2022
- 4 Drawbells have been constructed.
- The Crusher 5 Silo Support has been completed.
- Crusher 5 Workshop overhead crane was installed and commissioned.