Fabricating six massive reactors that are over three storeys high in Gauteng and then transporting these more than 2 500 kilometres to a mine in the Democratic Republic of Congo (DRC) – where all 3265 parts fitted perfectly, with not even one of the 26 900 bolts out of place – is a massive achievement.

This is according to Southern African Institute for Steel Construction (SAISC) CEO Amanuel Gebremeskel, commenting on the Azmet Reactor project, a collaborative effort led by Viva Engineering, an innovative and deserving 2023 Steel Awards Mining and Industrial category winner.

“The project entailed the detailed design of complex geometry with finite element (FEM) modelling, and integrated support frame and platform. As such, it exemplifies precision engineering, showcasing intricate design and fabrication processes.To appreciate the complexity thereof, one has to consider how to plan, design and fabricate such huge 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,” Gebremeskel says.

He goes on to explain that the more conventional approach would be to use heavy concrete tanks; or 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 – allowing 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 huge reactors – but also, several other complex tanks, as well as platework and plant buildings. From a technical point of view, engineers had to consider the design of the vessel in relation to permanent, material, equipment and wind loads.

Due the nature of the spliced connections, these had to be modelled in detail, including all the bolts. Furthermore, as the vessels had to be transported and erected piece by large piece, a lifting study first had to be performed. This 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.

Shaping up and shipping out

Gebremeskel says that the aspect of this project that stood out the most during the judging process was the logistics: “They designed each large structure in a modular fashion, for ease of transport and installation. However, bear in mind that these structures have a diameter of 9.9 metres and a height of 11.6 metres – which is almost the size of a 3-story building!”

The road transportation therefore necessitated exacting tolerances to ensure safe and timely delivery to site in the DRC. 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 minimise the number of loads to site

“The essential brilliance of this project lies in the smooth coordination and orchestration of design, fabrication and erection. This process was perfectly choreographed by the project managers who oversaw the planning down to the finest detail,” Gebremeskel observes.

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 prior to leaving the Viva Engineering workshop in Gauteng.

Here too, Gebremeskel says, adjectives such as ‘innovative’ and ‘ingenious’ come to mind.

“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,” he points out.

Maintaining the continuity of the rubber lining between the bolted faces of each component was successfully addressed, as the project brief explains: ‘The first reactor was trial assembled to prove that the jigs and manufacturing was correct. All six rubber-lined reactors were installed without a single flange hole out of place. Rubber lining is continuous on the bolted faces. This required that the fabrication details incorporated the lining thickness. During fabrication, spacer plates were also inserted in the connections to simulate the lining. Corrosion protection was furthermore applied to the external surfaces of the component’.

Joining quality with manufacturing excellence

Yet another innovative aspect of the Azmet Reactor project is the precision welding required to join the panels during the fabrication process, so they could be bolted together once on site. The level of welding precision and accuracy had to be very high, as the structures could not distort during the transportation process.

“A lot of the design had to cover exactly how to lift and maneuver these large and very heavy modular structures. The most significant load is during the lifting process – as opposed to when they are in use – entailing a very different kind of engineering. The entire design is driven by how one plans to construct and then transport each structure – as opposed to its ultimate application,” Gebremeskel continues.

The benefits of steel in this project were numerous, as detailed in the project brief: ‘The complexity of the reactor geometry is best suited to fabrication in steel. Construction of the reactors…in concrete would not be viable due to the complexity of formwork and deployment of plant onto a site of limited size. The benefit of steel for this application is a relatively lightweight structure (compared to concrete), which can be preassembled and trial-erected before being transported to site. This allows for fast and accurate erection in the final location’.

A precise and praiseworthy precedent

One of the chief challenges, according to Gebremeskel, 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.

“The Azmet Reactors project represents a veritable feat of engineering – showcasing brilliance of design, logistics and installation – and demonstrating the South African steel sector’s capability to execute structurally and logistically complex projects with praiseworthy precision.

This is indeed a victory for our 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.

Custom engineered chutes are scientifically designed and simulated prior to manufacturing by Weba Chute Systems to give customers optimal uptime – but the company has also innovated ways to keep these transfer points well maintained.

Channeling the flow of mined material is among the most onerous tasks on any mine, and Weba Chute Systems designs and manufactures its solutions to withstand these demanding applications. The considerable wear on the components in a transfer point, however, requires constant monitoring and attention. The company has therefore developed a range of responses to help customers to manage this important responsibility.

According to Izak Potgieter, ISO Systems Manager at Weba Chute Systems, a vital role is played by the company’s technical advisors, who visit customers on a regular basis to check the operation and condition of the chutes.

Chute inspection app

“To make their work efficient, and to quickly provide the customer with relevant information, we developed our own chute inspection app for our technicians,” says Potgieter. “This allows them to capture the necessary data and photographs from their inspection, to generate an automated report to guide the customer in their decisions.”

The company also has a reliability model which tracks the duty and condition of each chute over time, and which can inform a predictive maintenance programme. Through its decades of experience, the company has developed a detailed understanding of chutes’ wear trends under varying material conditions.

“Using these models, we can help customers to predict – weeks, months and even years in advance – which aspects of the chute will need maintenance,” he says. “This allows the necessary planning to be done, so that unexpected failures do not occur.”

He notes that Weba Chute Systems’ ISO 9001 accredited quality processes ensure that the spare parts manufactured at its advanced Wadeville facility are consistently what customers require. Collaborating with customers on their maintenance needs therefore also ensures that the right parts are available when required.

Faizel Mahomed, Client Services Manager at Weba Chute Systems, explains that mining conditions at customers’ operations can be expected to change over time. More abrasive ore, for example, or larger lump sizes, may result in faster wear on certain components.

“This makes our close contact with customers even more vital, as we can work with them to adapt to changing conditions,” says Mahomed. “Sometimes increased wear is unavoidable, and we develop innovations that meet these demands – such as our collaboration with a foundry partner to develop liners with 600 Brunel hardness for longer life.”

Among the faster wearing items on a chute is the lip, and to save time Weba Chute Systems has developed a quick-release lip for ease of replacement. He also points to the company’s innovation of a liner that can be replaced from the outside of the chute. This makes it safer and more efficient for the technician, who does not need to enter the chute.

Chutes are often mission-critical for a mine, emphasises Potgieter, and in these cases the customer can take advantage of Weba Chute Systems’ maintenance contracts. These arrangements put a dedicated team on site to monitor and report on equipment condition, and to coordinate the necessary maintenance with the mine’s responsible officials.

The automatic choice

Steel is an automatic choice because of its qualities. Mainly, due to its durability and versatility, steel is the preferred material in the development of structures and infrastructure.

The market 

The steel market is diverse, defined by shape, size and type. Based on market developments in the past few years, in the main, the sector can be dissected into the following categories:

1. Long steel and flat steel 

Long steel is segmented into wire rods, rebars, merchant bars, and heavy sections, among others. Flat steel is subdivided based on product type into hot-rolled wide strips, and quarto plates, among others.

2. Type  

From a type perspective, the market is segmented into carbon steel, alloy steel, stainless steel, and tool steel. Typically, the composition of steel produced depends upon end-users’ desired applications.

Demand and supply

These steel categories have to be available as and when needed. Typically, companies in downstream industries source locally, where it is available, and import it from other countries. The dominant local steel-producing countries on the continent are Egypt, South Africa, Nigeria, Kenya, Tanzania, Morocco, and Namibia.

Africa Iron & Steel Market Outlook Report 2021-2029, a research review of the state of Africa’s steel market was published recently. Its findings reveal interesting trends.

In local production, there is an increase in specialised steel alloys. Steel alloys are designed to meet the demand for steel with enhanced characteristics.

Another intriguing observation is the extent governments are going to protect local producers from imported steel through legislation. The Department of Trade and Industry in South Africa is a case in point (see sidebar).  The DTI has made it a condition for the use of locally-produced materials in projects. This is to facilitate development and employment creation.

However, it is palpable that local production cannot meet the volumes of demand or some of the specifications in projects. From a price perspective, the majority of downstream industry players consider locally-produced steel uncompetitive, as industry body Steel Tube Export Association of South Africa’s (Steasa) Chief Executive Officer, Keitumetse Moumakoe, lamented in a press statement last year. Certainly, imports will continue filling the void in the foreseeable future.

In contrast, in other steel-producing countries, there are no significant restrictions on imports. Presumably, market forces dictate. The downstream industry players in those countries do not have big concerns.

What’s in store for the downstream industry when all is said and done? 

Prospects

On the project front, based on the recent developments, prospects for steel producers appear bright. Most countries in sub-Saharan Africa plan to build more plants to meet the increasing electricity demand. Besides, electrification projects are either ongoing or in the pipeline.

To complement this, countries are diversifying their energy mix to accommodate renewable and are constructing solar power plants.

These developments have the potential to sustain steel demand for a while. Fabricators will be involved in producing steel towers for the transmission grid and distribution infrastructure, steel frames used in solar installations and wind turbines and boilers for power plants.

All in all, granted, the future trajectory of the comings and goings in the market for steel cannot be predicted with certainty. Nonetheless, there is one constant: as long as construction projects are ongoing, you can bet your bottom dollar that steel will always be in demand. Imports will ensure supply certainty.

Sidebar

Protecting the local turf 

South Africa is never short of intriguing developments in many spheres. These have not spared the steel sector.  In a move considered extreme by players in the downstream industry, the country introduced protective tariffs on primary steel hot rolled coil (HRC) and coated steel. Supposedly, this was aimed at curbing the influx of imported steel into the country to protect AMSA, South Africa’s sole domestic steel producer.  

However, this hasn’t deterred the inflow of imports. The downstream industry prefers imported HRC steel due to competitive pricing and access to variety. Ludovico Sanges, the managing director of Duferco, one of the players, says his company has been able to compete successfully in the international market using imported HRC steel.  

Imported steel accounts for about one-third of the country’s steel consumption, according to a new Steel Report published by the South African Iron and Steel Institute (SAISI). If truth be told, this could be a conservative estimate. Despite being cushioned by tariffs, AMSA has not been able to sustain its operations. The decision to close its plant in Boksburg indicates this. Annual domestic steel production capacity in South Africa is estimated at 6.5 million tonnes. With the reduction of AMSA’s capacity, this is set to plummet. The downstream industry will use more imported steel in its projects.

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Leveraging over a century of experience, Murray & Roberts Cementation is working with some of the world’s most respected mining companies to pave the way for safe and efficient underground mining.

According to Graham Chamberlain, New Business Director at Murray & Roberts Cementation, the busy pipeline of projects demonstrates the mining sector’s faith in the company’s unsurpassed industry knowledge and depth of skills. In southern Africa, the main projects underway are at De Beers’ Venetia Mine, Ivanhoe Mines’ Platreef project and Palabora Mining Company.

At the Venetia Underground Project near Musina, work has been ongoing since 2013 in one of the largest investments in South Africa’s diamond industry in decades. Transitioning from opencast to underground mining will extend the mine’s life until 2046. Murray & Roberts Cementation has been engaged in sinking, lining and equipping of two shafts – the production and service shafts – to a depth of 1,080 metres. The company also developed a decline tunnel and is completing associated surface and underground infrastructure, in a project whose scope included raiseboring work to establish ventilation infrastructure.

“In this maturing project, the mine is now getting into ore and starting to develop the infrastructure levels,” says Chamberlain. “At the shaft bottom, good progress continues to be made with the construction of workshops, pumping stations, silos and loading arrangements.”

Trafo Power Solutions has supplied 40 dry-type mini-substations, as well as seven standalone ring main units, to one of the Africa’s largest and fastest growing copper operations, situated in the Democratic Republic of Congo.

“We are immensely proud to be involved in this mega project,” says David Claassen, Managing Director at Trafo Power Solutions. “Considerable design work and planning went into this contract, with very demanding lead times to keep up with the mine’s rapid expansion.”

The mini-substations include units of between 630 kVA and 1,600 kVA capacity with primary voltages of 11 kV and 33 kV. The secondary voltage configurations are 400 V, 690 V and 1,000 V – and some units have dual-ratio secondaries. Protection against the ingress of water and dust was also designed into the units, with an IP54 ingress protection rating.

Fully designed and manufactured in South Africa, the mini-substations were completed in a streamlined production process that facilitated a fast track delivery in batches of five to six units every 10 days. After the manufacturing and assembly process, each unit went through a programme of intensive testing before it was ready for dispatch.

“The units are designed to be as compact as possible,” he explains. “While many will be used for surface infrastructure, the design had to ensure that they could be used underground, where space is limited.”

Safety regulations

The underground environment is governed by stringent safety regulations and standards, making the dry-type transformer an ideal choice. This technology uses air rather than oil to cool the windings, making it safer with less risk of fire, explosion or environmental contamination through leakage. The windings in dry-type transformers are also encapsulated with cast resin, protecting them against humidity levels up to 95%.

Undertaking both the electrical and mechanical design, Trafo Power Solutions has ensured a limited footprint through the use of air-to-air heat exchangers. Air is channelled through the transformer windings and flows over the aluminium tubes of the heat exchanger, while a fan blows air through the tubes to cool the air on their outer surface.

“The substation design also includes arc protection, which will shut the unit down in the event of an arc occurring – before any further damage can be caused,” he says. Each mini-substation is equipped with a control system that will allow the protection functions to be monitored remotely.

The contract was conducted through a leading South African engineering, procurement and construction management (EPCM) firm, and Trafo Power Solutions ensured that all units were delivered by the end of 2023.

“Our early engagement with the EPCM was important on this project, as it allowed our team to understand the project requirements and develop a cost effective solution,” Claassen says.

During this process, all documentation was strictly managed within an online system, including designs, specifications and test certificates – to which the EPCM and end-client had easy access. In this way, designs could be uploaded, shared and signed off using this platform, further streamlining activities for the fast pace of the project.

“The ring main units are fully motorised and controlled externally by remote pendant switching,” he says. “This enhances safety and ease of management, so that personnel seldom have to open the panel doors which requires the necessary safety equipment and protocols.”

The transformers are rated for Class H insulation – for temperatures up to 180 degrees – while the dual-voltage boards are sizeable for a relatively complex voltage distribution system on each mini- substation.

“The detailed design and variety of solutions within the complete contract package really highlights the technical capability of the Trafo Power Solutions team,” says Claassen. “This can be seen in the mini-substation from the medium voltage side and its control and protection functionality, through to the low voltage distribution and the customised transformer design for these applications.”

He emphasises that the standard attributes of dry-type transformers allow them to operate reliably with very little maintenance. With air rather than oil for cooling, for instance, they do not require any regular oil testing or oil changing.

The robust nature of dry-type transformers makes them well-suited for mining applications, whether surface or underground. Claassen notes that Trafo Power Solutions’ extensive experience in Africa reflects that dry-type technology is becoming more popular in the mining sector. The reasons for this trend include their inherent safety, their reliability and their ability to operate without much maintenance.