The fabrication, in South Africa, of six large reactors for the Azmet Reactor project, being undertaken at a mine in the Democratic Republic of Congo (DRC), is a “massive achievement” after it was awarded the Southern African Institute for Steel Construction (SAISC) 2023 Steel Awards Mining and Industrial category winner, reports SAISC CEO Amanuel Gebremeskel.

He explains that the fabrication of the six reactors, which are over three stories high, in Gauteng and their transport over more than 2 500 km to the mine in the DRC, was successfully performed following all 3 265 components being fitted at their final location “perfectly, with not even one of the 26 900 bolts out of place”.

“The Azmet Reactor project, a collaborative effort led by turnkey structural steel contractor Viva Engineering, is an innovative and deserving 2023 Steel Awards Mining and Industrial category winner,” enthuses Gebremeskel.

The project entailed the detailed design of complex geometry with finite element modelling and integrated a support frame and platform.

“As such, [the project] exemplifies precision engineering, showcasing intricate design and fabrication processes,” he states.

To appreciate the complexity of the project, Gebremeskel details the planning, designing and fabrication of such large modular structures ahead of time, in such a way that they can be moved through four or five different countries by road to install on site at the mine.

He explains that the more conventional approach to meeting the demand for such large reactors would be to use heavy concrete tanks or to set up a substantial design office and fabrication works with a highly skilled team – both of which are not readily available locally in the DRC.

Using an established South African fabricator based in Gauteng, therefore, provided a viable alternative, as it enabled for a controlled environment and close monitoring to ensure that all construction materials and structures met the required quality and safety standards.

Poring over the Project

The Azmet Reactor project not only involved creating six large reactors, but also several other complex tanks, as well as platework and plant buildings.

From a technical perspective, engineers had to consider the design of the vessel in relation to permanent material, equipment and wind loads. Owing to the nature of the spliced connections, these had to be modelled in detail, including all the bolts.

Further, as the vessels had to be transported and erected piece-by-piece, a lifting study first had to be performed, which focused on the selection of the most appropriate lifting methodology, considering that the reactor components would need to be loaded onto conventional heavy-duty transport vehicles.

On the opposite end, at the mine in the DRC, careful consideration was given to the constructability of the project.

Gebremeskel says that the aspect of this project that stood out the most during the awards judging process was its logistics.

“The manufacturer designed each large structure in a modular fashion, for ease of transport and installation,” he says, highlighting that the structures have a diameter of 9.9 m and a height of 11.6 m.

The road transportation therefore necessitated exacting tolerances to ensure safe and timely delivery to site.

Transport jigs were designed and built to brace the components and reduce vibration during transportation, while meticulous load packing optimised weight distribution for the lengthy trip.

All the components of each reactor were packed so that upon arrival on site, it could be assembled from the designated package.

The components also had to be carefully packed in specially designed cradles to optimise each load and reduce the number of loads to site.

“The essential brilliance of this project lies in the smooth coordination and orchestration of design, fabrication and erection,” Gebremeskel observes.

He adds that this process was “perfectly choreographed” by the project managers who oversaw the planning down to the finest detail.

The Tank Logic

Reactors are essentially large tanks that are custom-made to remove precious metals from mined ore and must tolerate a variety of different temperatures and chemicals.

A rubber bladder required to protect the steel from these compounds therefore also had to be installed before leaving the Viva Engineering workshop.

“The lining is put on the inside to protect the steel from whatever solvent is being used. As one can imagine, it is necessary to do some fairly detailed mockups and even trial assemblies to test this.”

The reactors were eventually bolted together. This meant that the lining had to work in a bolted tank rather than a conventionally welded one.

In terms of project delivery, one of the primary challenges was completing the project on time, as late delivery would have resulted in substantial penalties.

“Needless to say, timeous delivery was achieved against all odds,” says Gebremeskel.

He says this project is a victory for the industry, which could certainly not have been achieved elsewhere on the continent.

“Considering the number of mines being constructed throughout Africa, the good news is that similar projects will no doubt be required, which our local steel supply chain can certainly deliver,” he concludes.