Stacking and reclaiming play a huge role in operational efficiency and production streamlining as capacity increases at Kumba Iron Ore’s massive Sishen mine. The Bed E materials handling expansion project, tasked to deliver on such functionalities, has been a resounding success thanks to ThyssenKrupp Materials Handling, writes Laura Cornish.

ThyssenKrupp Materials Handling (TKMH), a division of ThyssenKrupp Industrial Solutions South Africa, has been supplying stackers and reclaimers to Sishen – the largest opencast iron ore pit in Africa – for over 40 years. Its latest project on-site, completed in July last year, acknowledges the instrumental role its equipment plays in the mine’s overall operational capabilities.

Sishen is a large volume operation, mining about 171 Mtpa (including waste) – as reported in Kumba’s 2012 financial year-end results. And this is set to increase as the main pit dips to the west and the ratio of waste to product increases. Ever-increasing volumes require equipment capable of moving large tonnages of the hard rock material typical to the Sishen mine. This has resulted in various on-site projects aimed at accommodating this, including the Bed E expansion project.

“In March 2010, we were awarded the full turnkey Bed E expansion project, which had the sole purpose of increasing Sishen’s overall stacking, reclaiming and storage capacity,” explains TKMH’s marketing manager, Willie Agenbag.

“The project, which included all civil, mechanical and electrical work, saw us remove the small TKMH stacker as well as its feed conveyor and two small TKMH TAS27.5 reclaimers that has been in operation since 1971. We then extended the bed to 40 m in width and 365 m in length to accommodate a larger volume stockpile. We upgraded and installed new conveyors, and supplied and commissioned a larger 4 000 tph luffing and slewing stacker. One of the most rewarding elements of the project was replacing the two small reclaimers with a new generation, larger, uni-directional TAS40 drum reclaimer, with its associated conveyors, which had to feed  via a new transfer house and link conveyor into the existing system,” Matthias Göing, TKMH sales manager continues.

The new drum reclaimer (a TAS40), which spans 40 m, is equipped with 64 buckets and is big enough to handle up to 5 500 tph of continous throughput.

The transfer car pit was also extended to reach Bed E, thereby enabling Kumba to use any of its three TAS40s across all of its reclaiming beds (A-E) using the existing TKMH transfer car. The transfer car may appear to be a simple device, but is capable of moving a 40 m wide machine weighing around 450 t across multiple beds.

Even though its equipment can be described as ‘giant-sized’, dwarfing the people who operate it, attention to the smallest design and engineering details is essential. “During the design phase we had to ensure that the new drum reclaimer would fit any of the beds, which required interface checks with various other equipment and structures, and adaptations to TKMH’s latest, more operator-friendly designs, enabling it to move seamlessly between beds.

While there are numerous different reclaimer types, Göing explains that the drum reclaimer delivers the best blending results at constant high throughputs. “The machines also perform reliably under severe conditions, which in Sishen’s case include high temperatures, high dust levels and abrasive material characteristics – due to their mechanical simplicity and gentle reclaim action.

“We successfully completed the project in July 2012, on time and within budget, and have a satisfied client to prove it,” acknowledges Stephen van der Walt, project manager for the Sishen Bed E project. And even though the TAS40 replaced two machines, Sishen still boasts the highest concentration of drum reclaimers in the world, which thanks to TKMH includes seven reclaimers and five stackers.

Machines that keep on giving, and giving

While the capital outlay for a reclaimer or stacker is significant, the payback return is quick. “Our fully automated machines must work continuously for the majority of their lifespan.” TKMH reclaimers (and stackers) are no stranger to the demanding requirements of Sishen and have successfully met the mine’s needs for decades.

Every TKMH machine ever supplied to Sishen that is still on-site remains operational today, which for some machines equates to 40 years. “We are extremely proud of this, considering a typical reclaimer or stacker is designed to operate for between 25 and 30 years with the correct maintenance.

“This means that our original machines have delivered many more years than the expected lifespan of what they were originally designed to do. The new generation machines, including small design modifications to meet the needs of the specific material and movement requirements, are expected to deliver even longer lifespans – if operated correctly and maintained properly,” Agenbag notes.

Truly local

TKMH prides itself on being a truly South African company. All design and fabrication work is performed and undertaken locally which provides employment opportunities and substantial benefit to local communities.

TKMH timeline at Sishen – machines pushing past their limit

1971:  TKMH supplied two drum reclaimers to the south plant (no longer operating)

1973: TKMH supplied two stackers, two TAS40 drum reclaimers and a transfer car; the reclaimer drums featured the double shell design.

1979:  TKMH supplied a system for handling coalcrete overburden, including a semi-mobile crusher and a crawler mounted spreader.

Late 1980s:  TKMH changed its reclaimer drum design to a single shell

2005 to 2008: TKMH supplied four TAS41 drum reclaimers (two for ROM and two for product), three stackers and a second transfer car as part of the Sishen Expansion Project.

2009 to 2010: TKMH supplied one off TAS41 product drum reclaimer

2010 to 2012: Bed E expansion project, including a larger replacement stacker and a single drum reclaimer, replacing two smaller ones.