In early 2021, Afrimat commenced the underground mining phase at Nkomati. With the tarnished history of the mine and underground mining in general, it was a bold step forward. The primary objective of this project was to access 20 million tons of high-grade anthracite coal, which could not be mined by opencast due to the depth below surface.
As part of the risk-mitigating measures, a truly experienced team of miners was sourced, and very careful mine planning was required. We gathered a team to refurbish the equipment but, more importantly, to sink a new decline shaft to access the valuable anthracite seam. Remarkably, we decided, in true Afrimat style, to undertake the inclined shaft project in-house and not employ a specialist contractor for the work.
The collective experience of the qualified miners and production supervisors involved (all near retirement age) was impressive and a testament to the skills and knowledge on hand. To bolster the future underground management team, two of Afrimat’s young mining engineers were redeployed to the project to acquire the necessary technical competence for this very specialised mining effort.
The project commenced in November 2021. A new semi-box cut was blasted into the side of an existing ramp to create a competent highwall. Two shafts were then developed at 8°-12° through challenging geological strata to the coal intersection some 85m below ground level.
All relevant infrastructure was established near the shaft entrances. These included back-up generation for loadshedding, stockpile conveyors for product delivery, a complete lamp and control room, and massive air-circulation fans. An unsatisfactory geological fault approximately halfway down resulted in a significant deviation that delayed the project by more than 12 weeks. Approximately 100m of tunneling was abandoned and rerouted in another direction.
Expected ingress of seepage water and bad underfoot conditions were dealt with on a weekly basis while a safe environment was established and maintained for the duration of the project. Strategically, it made sense to employ rental rock-moving equipment while operating in the harsher rock formations, but ultimately, we had to acquire two new load haul and dump machines to complete the last 20% of the work.
The top of the coal intersection was reached in August 2023. The development of the shaft bottom commenced shortly thereafter to establish a five-road section in the coal to enable us to produce some 20,000 ROM (run of mine) tons per month. The full shaft development was completed by the end of October 2023. The project crew was made up of hardworking mining and engineering staff who all work for Afrimat. Their dedication and enthusiasm bode well for the success of the Mangweni Underground Shaft.
Salient Features of the Mangweni Underground Decline Shaft Project
- Total cost of project: R144 million
- Shifts worked: 2 x 9 hours Monday – Friday; 1 x 9 hours on a Saturday
- Metres drilled by hand: 977m
- Volume of rock material mined: 18,000m³
- Lost Time Injuries: 1 minor case
- Total staff complement for shaft construction: 70
- Planned staff complement when in full production: 110
This project exemplifies Afrimat’s commitment to innovative and bold mining solutions, ensuring the continued success and sustainability of our operations.
