Northam Platinum’s R5.6 billion investment in expanding (or nearly quadrupling) its Booysendal PGM production to approximately 500 000 ozpa is a significant capital investment – showing the company’s confidence in South Africa and the future of the PGM market.
And impressively, the project is on time, on budget and incorporates materials handling technology of a magnitude never before seen in Africa, says Booysendal general manager Willie Theron.
This article first appeared in Mining Review Africa Issue 6 2018
Northam Platinum’s vision to build a world-class, large-scale operation producing 500 000 ozpa by 2022/2023, is on the horizon as the company passes the half way mark in delivering one of the largest expansions ever undertaken in the platinum sector at its Booysendal operation, situated on the southern tip of the Eastern Limb of the Bushveld Igneous Complex.
Quick and easy scale-up of the original mine
The original Booysendal operation – a 160 000 ozpa 4E operation now referred to as the North UG2 mine – was really just the start of greater things for the mine.
Having successfully operated at its design capacity shortly after moving into production in 2013, Theron has overseen the expansion of the mine (through a deepening project) and the introduction of a new, standalone North Merensky section.
The deepening project Theron explains entailed the development of two additional levels at the North UG2 mine, which is currently building up to a new steady-state capacity of 180 000 ozpa.
“We are on track to achieve this in our current 2018 financial year,” he confirms. Northam Platinum’s financial year runs from July to June.
The new North Merensky mine, situated in close proximity to the UG2 mine, which commenced development in FY2016, has already reached its initial steady-state design capacity of 25 000 tpm ROM material.
The plan is also to increase this production volume to about 65 000 tpm in the next four years.
“Our expansion efforts will together increase our FY2019 production quite significantly,” Theron points out.
“We are targeting between 205 and 210 000 ozpa for our new financial year and have a process plant, that although is now at capacity at 230 000 tpm (before dense media separation), can comfortably deliver on these production targets moving forward. Nonetheless, plans are already underway to handle the larger volumes from the Booysendal North Merensky in the coming years.”
The big expansion
It is the introduction of a big new mine – Booysendal South – that will elevate the operation’s production levels quite substantially.
“After a continuous relationship spanning over nine years from the concept of Booysendal, Northam appointed DRA as the main EPCM contractor on this project.
DRA was responsible for conducting relevant feasibility studies followed by the initiation of the various projects,” says DRA Booysendal project manager Eddie Badenhorst.
Situated just 4 km south of the North mine (as the crow flies), the Booysendal South project, will comprise a central complex which includes:
- Booysendal Central UG2
- Common boxcut with seven addits splitting into:
- BS1 – 4 barrel decline cluster
- BS2 4 Barrel decline cluster
- BS3 (future replacement decline cluster
- Booysendal Central Merensky
- BCM1 Merensky addit
- BCM2 Merensky addit
- Old Everest workings which includes an existing Valley boxcut
- Future decline cluster replacement option
- Concentrator plant (part of Everest acquisition)
The Central mining complex consists of a 650 m long high wall (140 m wide box cut and a 350 m wide terrace) at a maximum height of 32 m.
The combined high wall area of 16 000 m2 was stabilised. The terrace area is 650 m long and a maximum width of 22 0m.
The Booysendal Central UG2 mine will operate similarly to the North UG2 mine – using a mechanised bord and pillar mining methodology. It will however comprise a single portal system which splits into two declines.
“The initial milestone was to establish the box cut and thereafter establish the seven portals required for access. The boxcut was successfully completed by May 2017. The first blast on the portals took place on 21 May 2017.
“Currently all of the seven portals have intersected reef and the split of the BS1 and BS2 4 barrel decline cluster established. The civils and towers installation of our aerial rope conveyor system – an exciting element of the project – has also been completed,” Theron reveals.
At a ROM rate of 230 000 tpm, a mine of this size will require adequate ventilation and access for the workforce, which explains the necessity for seven adits.
The infrastructure to support the larger Booysendal operation is an impressive feat in itself and included the construction of a 12.75 km road connecting Booysendal North to Booysendal South and access to the growth projects.
“The road, which in essence is like a winding mountain pass, is surfaced, in use and was built according to provincial road standards,” Theron notes.
The road surfacing required 17 445 t of asphalt and earthworks comprised 337 570 cubic metres of earth that had to be moved and placed.
“A limited environmental footprint and tough ground conditions presented some serious challenges for the team.
“Having worked around these challenges the end resulted in the 12.7 km surfaced road that consists of a North and South portion,” Badenhorst explains.
The North road alignment crossed 38 streams or river crossings that resulted in 530 m pipe-culverts and 119 m box-culverts. 682m3 concrete with 15.4 t of steel reinforcement was used during the culvert constructions.
The South road alignment crossed 47 streams or river crossings that resulted in 935 m pipe-culverts. 1325m3 concrete and 20 t of steel reinforcement was used during the culvert constructions.
One of the unforeseen circumstances that had to be addressed on both roads was the ever-changing geology and boulders that came from the excavations. 45 000m3 of boulders on the North road and 49 000m3 on the South road Badenhorst continues.
Of even greater significance is the materials handling system required to move the mined material to the original Everest process plant – situated nearly 5 km away.
“In order to reduce our impact on what is considered an environment-sensitive area, we elected to use a conveying system that reduces our footprint, is very cost effective and will quickly and easily convey our material to the process plant,” Theron reveals.
Innovation in abundance: Building the South RopeCon
The RopeCon system was elected as the best solution for Booysendal South’s material transfer needs.
In essence, it will comprise a series of towers, strategically positioned between the mine and plant, connected by ropes and conveyor belt which will run the entire distance above ground.
“The RopeCon system used on the Booysendal project is a unique system and a first of its kind in southern Africa, also currently noted as the longest RopeCon in the world,” Badenhorst notes.
The distance of the system is 4.7 km, and the lift 530 vertical metres. The towers will house six ropes – 2 x 52 mm diameter ropes, 2 x 47 mm diameter ropes and 2 x 37 mm diameter ropes.
The combined length of all the ropes is a massive 29 km. A helicopter was used to manoeuvre the pilot ropes into place which will pull steel ropes that will in turn pull the six RopeCon ropes into place.
The conveyor belt will operate at 2 400 kW with a breaking force of 1 600 kW.
The drive pulley diameter is 2.3 m and the civil foundations for the drive station complete.
“From the loading station, the conveyor belt will travel across 12 towers which are tall and large to accommodate a 1 150 tph tonnage rate. The tallest tower stretches 59 m in height and the longest span between two towers is a substantial 878 m. The volume of concreate alone required for the foundations of the towers totalled 2 827 cubes and another 236 t of rebar.
All 12 towers have been erected and the ropes pulled through and connected. “We anticipate commissioning our RopeCon by the end of this year,” Theron confirms.
A 4 200 tph silo, 36 m in height and already built, will feed the loading station at the mine and discharge the material at the process plant drive station.
“This element of the project is unique in Africa, especially in terms of its magnitude and we are extremely proud of the successes we have already achieved to date in building and installing it.
“It has a small footprint, is 10 times more cost effective than a conventional system that has to deliver the same tonnage requirements and overcomes our mountainous typography challenges,” Theron highlights.
Discussing the timeline for the build-up of operations as the central complex, Booysendal will commence with ore stockpiling at the concentrator once the RopeCon is commissioned.
This will enable the project to start feeding the concentrator with a 400 – 500 000 t UG2 stockpile in early 2020 and slowly build the concentrator back to capacity as the underground mines develop further.
Apart from the sheer size of the RopeCon, other challenges faced during construction included compliance with electrical standards and the precise design interfacing between the RopeCon and other infrastructure elements connected to it such as the silo and an existing conveyor at Booysendal South.
Bulk material flow simulations were conducted to ensure chute designs at the RopeCon was optimal, Badenhorst outlines.
The civil designs were completed by DRA Global with geotechnical input from ARQ Consulting.
Doppelmayr mobilised on site during January with a crew of 13. The tower installation was completed two weeks prior to schedule and can be credited to the high quality of civil construction completed on time by GLTA.
Currently 177 shipments have been delivered from Austria on site, with outstanding shipments nearing completion.
Along with standard surface infrastructure such as smaller roads, office buildings, stores, workshops and dams, the Booysendal mine will include state-of-the-art technology built into its control centre and change house.
The control centre, located on the surface, will be able to control the underground mine functions remotely, and the modern change house will boast a solar driven heating system capable of producing hot water for over 2 000 people – drastically reducing electricity usage.
To further limit its impact on the environment, the Booysendal mine will make use of three vertical fan stations to provide suitable ventilation over the life of mine.
These fans required a smaller footprint and have less effect on the environment.
The power required will be supplied from the current North mine, construction of a 132 kV power line from North mine to South mine has commenced. This will include a newly built substation at South mine able to provide power to South mine and any future expansions at South mine.
Preparing the South concentrator for start-up
While a minimal amount of work is required to restart the old Everest concentrator, which historically processed up to 300 000 tpm, Northam will use the material collected from the Booysendal South tailings dam to prepare the concentrator for a full restart.
“We have for the last eight months been re-mining the Booysendal South tailings dam recovering chrome and a second phase will be to recover some PGMs while upgrading and repairing in small increments to various sections of the south concentrator. With a remaining lifespan of 22 months, there is more than enough time to complete this.”
FY2022 the big date
Theron is confident that the entire Booysendal mine will be operating at a steady 470 000 ozpa by FY2022/23 – “with upside to get to 500 000 ozpa when combining the (North UG2 and Merensky mine (at 65 000 tpm), Central (BS1 and BS2) BCM1 and BCM2 Merensky mine as well as the BS4 (old Everest portion).”
“We are positive about South Africa, our product, our company and our people which can together deliver on our production goals as far down on the cost curve as possible. The PGM sector is definitely constrained at present but we have a longer term view and will capatalise on this when our market turns.”