Recycling of waste material is a no-brainer for the planet, and suitable screening applications have to be developed to make it a reality.

“Everyone wants to recycle more; it makes sense environmentally and it’s the right thing to do,” says Kwatani business development manager Warren Mann. “Recyclable waste is generally low value, however, so any recycling solution must have a highly cost effective strategy for separating different elements of the product.”

Mann highlights that, unlike most mined material, the shape and other characteristics of products that industry wants to recycle are often irregular and difficult to screen. Strands of copper wire, for instance, simply do not pass through a screening medium as easily as aggregate stone or sand. Similarly, chips of rubber produced by a tyre shredder are also likely to be highly varied in shape, size and consistency. 

“This means that anyone wanting to screen industrial waste in a commercially sustainable way is unlikely to find an off-the-shelf screen design to do this,” he explains. “Detailed testing of material on different screens – or with a range of screening dynamics and parameters – is usually the only way to find a cost effective solution.”

The real challenge is that most recycling demands an economy of scale, in which a sufficient volume of material can be effectively recycled to overcome the low margins of the final product. It is therefore not enough to find an in-principle solution; the duty that a screen must accomplish is a key variable in its success. 

“Kwatani has decades of experience in understanding customers’ screening needs, so we can design and manufacture a screen that is fit-for-purpose,” he says. “This expertise extends across a range of material and commodities – making us familiar with how different products respond to screening.”

The company’s testing laboratory is where investigations tend to start, and customers can witness how their material performs under different screening conditions. Mann explains that a machine used to screen corrosive products like crushed batteries would need to be built from specialised materials of construction , for example. There are also materials that tend to clog the screening surface, so a self-cleaning kit may be required. 

“No matter what the material is to be recycled, Kwatani is well placed to test how it responds to a range of screening options, and to make recommendations to customers,” he concludes. “The testing we conduct will give recyclers valuable insights into how best to proceed, by avoiding the trial-and-error method that costs them more in terms of time, effort and resources.”

South African based vibrating screen and feeder original equipment manufacturer (OEM) Kwatani reports that orders for its equipment have surged in recent months to record levels, with orders coming not only from South Africa and the southern African region but also overseas markets.

“The current level of business is the best we’ve ever seen since the company was founded nearly 50 years ago and every month now is turning out to be a record month,” says Jan Schoepflin, General Manager Sales & Service at Kwatani. “The growth is quite astonishing – in fact, 50 to 60 %, year on year.”

He adds that Kwatani is currently producing around 60 machines a month. “To keep pace with demand, we’ve rented an additional 3 000 m² of factory space to complement the 17 000 m² we already have,” he says. “Being part of Sandvik Rock Processing Solutions, which in turn is a business area within the Sandvik Group, we’ve also been able to outsource some production to other Sandvik factories overseas, including Sandvik’s Indian factory.”

One of Kwatani’s current orders – won in the face of intense opposition – involves the supply of over 70 screens and associated equipment to a large copper mining operation in Central Asia. This is the largest order in Kwatani’s history and probably the largest single screen order ever to be won by a screen manufacturer based in Africa. “We’re expecting another large order from this region shortly – it won’t be quite as big but will still be very substantial,” says Schoepflin.

Kwatani is also busy with two big contracts in southern Africa, one for a major platinum mine in South Africa and the other for a zinc project in the DRC. Both projects are in the construction phase.

According to Schoepflin, the surge in sales reflects not only more buoyant conditions within the global mining industry but also Kwatani’s membership of the Sandvik Group.

“We became part of Sandvik at the end of 2021 and this has opened many doors to us,” he says. “We’ve always been big in Africa and were, in fact, already ranked as the biggest screen manufacturer on the continent prior to being acquired by Sandvik but were less strong in certain other parts of the world. Being part of Sandvik has given us improved access to many markets, particularly in South America where Sandvik is the dominant supplier of mining equipment.”

Schoepflin also points to the quality of Kwatani’s products as another reason for the skyrocketing demand for its equipment. “We produce bullet-proof products that work reliably and efficiently and that have been proven in Africa’s mining areas, which are probably the toughest in the world in terms of the demands placed on machines,” he says. “Equipment that works well in Africa will perform anywhere.”

He adds that the fact that Kwatani’s equipment is manufactured locally is another major plus for the company. “Our manufacturing costs here in South Africa are low by global standards and our exports also benefit from the fact that South Africa’s currency, the rand, is very weak. The result is that our machines are very competitively priced.”

Kwatani forms part of Sandvik’s crushing and screening division within Sandvik Rock Processing Solutions. This now includes not only Kwatani and Sandvik’s own screening business but also the recently acquired mining related business of Schenck Process Group, making Sandvik the world’s biggest supplier by far of vibrating screens and related equipment.

Close monitoring is the basis for keeping vibrating screens productive and achieving the lowest cost of ownership, says Kenny Mayhew-Ridgers, chief operating officer of leading South African vibrating screen specialist Kwatani. Moving from paper systems to digital solutions is a vital step towards this goal.

“Where machine data recording – combined with periodic inspections and regular maintenance – can be captured in the digital sphere, you can generate a complete picture of the equipment’s lifecycle,” says Mayhew-Ridgers. “Real-time data monitoring is a game changer for screen reliability and performance.”

Wherever there are operational deviations from the prescribed norm, sensor-generated data can quickly alert the right people on the mine – giving them the ability to react timeously, he says. Importantly, this technology also allows patterns to be detected in the relationship between component life and throughput.

“By analysing these patterns, the mine can make well-informed decisions about its maintenance strategies, being aware of the optimal conditions for its equipment duty,” he says. “It also gives us, as original equipment manufacturers, the opportunity to compare machine performance in detail across different customer sites – so that we can adapt and advise accordingly.”

Where Kwatani sees one customer getting longer life from their exciters, for instance, the relevant data is easily available to make comparisons and identify distinguishing factors. He explains that Kwatani can monitor its vibrating screens using industrial sensors and measurement technology which is readily available and supported worldwide. In other words, it is not so specialised that it becomes unaffordable; neither is it so complicated that customers cannot maintain it themselves.

“What is key to the successful application of digital technology is that the raw data that we process must be analysed to become useful for decision making and planning,” says Mayhew-Ridgers. “This means streaming it seamlessly to databases, and allowing our customers to visualise the information effectively.”

To do this, Kwatani partners with system integrators and works closely with its mining customers so that the end-users get the most out of the information without spending time and money to process the raw data themselves.

This digital monitoring can also help to overcome a common challenge in many mining operations: working in silos. Paper systems do not easily lend themselves to sharing of data across different aspects of the operation. This in turn makes it difficult to improve equipment performance on a holistic basis. The availability of various streams of data on a single platform enhances transparency between service technicians, foreman, engineers and the OEM of equipment on site.

“This of course requires that we integrate our systems with our customers’ existing infrastructure, which is an important focus for us,” he says. “Whether greenfields or brownfields project, it is important that information be compatible and seamlessly shared.”

He highlights that the data generated is valuable not only for reflecting a machine’s current status, but because it can store an entire life cycle history. Digital systems can keep track of the equipment’s inspections, maintenance and operational performance over its lifespan.

“The insights gained from this can lead to improvements in the design, or in the way that it is operated,” he says. “This can result in better efficiencies, improved production or other benefits.”

In 2021 the multi-national Sandvik Group acquired Kwatani with its more than 45 year legacy as an original equipment manufacturer and it South African manufacturing facilities are set to become the global engineering and manufacturing base for vibrating screens and feeders for both local and international customers.

The company, known for its commitment to compliance with the South African Mining Charter, is a proudly Level 2 B-BBEE organisation and the internationally recognised Kwatani brand, with its promise of being engineered for tonnage, remains unchanged. The Kwatani brand will continue to be used across Africa while products sold internationally will be sold through the Sandvik sales channels under the Kwatani product name.

While low total cost of ownership (TCO) is a function of product quality, it is also about predicting maintenance intervals and optimising uptime. 

“Prediction and planning have become the pillars of quality aftermarket support,” says Jan Schoepflin, general manager sales and service at Kwatani, now part of the global Sandvik engineering group. “More than ever, OEMs must support customers with systems and services that pinpoint future needs.”

Schoepflin highlights that when equipment users adopt a TCO approach, they realise cost savings through smoother operations and less disruption, as there are fewer unplanned stoppages. 

“This approach should also extend the life of equipment, making it not only more cost effective but more environmentally sustainable,” he says. “As the name suggests, capital equipment is a significant investment and should last as long as possible.”

An important part of an OEM’s support role, then, is to help customers measure the condition and performance of equipment. This vital data allows users to plan better, by knowing what financing and maintenance will cost. This means more accurate proposals and reporting to management and board level. 

“Equipment owners can also outsource some of their business risk to supply partners like Kwatani,” he notes. “If an OEM claims a certain TCO for its equipment, owners should be able to hold the company to this promise, by delivering both reliability and performance at a given cost.”

He says Kwatani does this is by offering instruments like extended warranties and tonnage contracts to customers. By applying the necessary maintenance programmes with genuine spares, owners can benefit from cost certainty and operational uptime.

Planning for maintenance has become even more crucial given Covid-19’s disruption of the global supply chain. Kwatani’s aftermarket specialists work closely with customers to predict what maintenance and spares will be needed. With the risk of longer lead times, effective planning requires that certain stock be kept aside to supply specific customers’ maintenance programmes.

“OEMs with a proven reputation make it easier for users to trust a forecast TCO,” says Schoepflin. “With our focus on aftermarket services, we attract a high level of return business – making us more sustainable over time.”

He emphasises the importance of this sustainability, as customers know the company will be there in future to support the equipment they sell and uphold their TCO promise.

Competing with leading OEMs from around the world, vibrating screen specialist OEM Kwatani has snatched a mammoth export order for over 70 screens. 

The order was signed in April with a large copper mine in central Asia, which boasts a production rate of 35 million tons a year. According to Kwatani general manager sales and service Jan Schoepflin, the machines will be rolled out and delivered over a tight schedule of just eight months. Kwatani, now part of the Sandvik group, is already hard at work manufacturing the large and medium-sized screens at its South African manufacturing facility.

“This is Kwatani’s largest order to date and is probably the largest single order for screens ever placed on a company in Africa,” says Schoepflin. “We are proud to have won such a prestigious bid in the face of intense competition, showing how our global reputation has been growing.”

The order is for large double-deck multi-slope screens, which feed high pressure grinding rolls (HPGRs), as well as for single-deck linear screens feeding concentrators. The screens in this order will installed on isolation frames to minimise the extent to which dynamic loads affect the plant’s building structures. Kwatani is well known for its design, manufacture and servicing of large, robust screens which are engineered for tonnage. 

“As the largest OEM for vibrating screens and feeders in Africa, we have had great success on the continent and abroad with our large ‘banana’ screens,” he says. “These and our other custom engineered screens have been supplied to over 50 countries to date.”

The stringent and lengthy technical adjudication for this project was conducted for the mine by two leading international project engineering houses. The size and value of the order ensured that all the mining industry’s foremost screen suppliers were enthusiastic participants in the bid. Other indicators of the order’s scale are that the screens will consume around 700 tonnes of steel, and will altogether be fitted with 21,000 screening panels.

Schoepflin notes that an important consideration for customers is not only the proven quality and performance of its screens, but Kwatani’s ability to deliver on time. 

“Any large capital expenditure decision on a mine is taken with time-sensitive factors in mind,” he says. “For instance, the delayed delivery of critical equipment can prevent a mine from meeting its planned production targets. This undermines the financial basis for that decision – an eventuality that no mine can afford.”

The end-customer and the project houses therefore had to have full confidence in Kwatani’s capacity. With growing demand from a buoyant mining sector, the company recently added another 3,000 m² to its existing 17,000 m² facility in Spartan, Johannesburg. Its design and manufacturing capabilities are ISO 9001:2015 certified, ensuring that the latest order to Asia will comply with the highest global standards, he says. 

“We also pride ourselves on the quality and resilience of our supply chain, which underpins our ability to manufacture to demanding deadlines,” he says. “We carefully select our supply partners – most of whom are local enterprises – and collaborate closely with them to build their sustainability and responsiveness.”

To keep the project’s schedule on track, dedicated in-house project managers and procurement specialists meet regularly with supply partners to ensure a smooth and streamlined process. This has required perfect alignment of all local and global procurement, including motors, drives and steel. The company’s agility allowed contracts and prices to be tied down for timeous delivery, despite the global supply chain disruption that lingers from the Covid-19 lockdowns. 

“The scale of the mine’s operation indicates that screen efficiency, throughput and performance will be paramount,” he says. “We subject all our vibrating equipment to rigorous tests in our in-house testing facilities prior to dispatch.”

This, he explains, enables customers to achieve continuous tonnage while protecting its assets and reducing the total cost of ownership. Even before manufacturing stage, each design is subjected to Finite Element Analysis (FEA) as a standard procedure to verify engineering integrity. 

Reflecting the journey of the screens from inception to operation, each screen has its own ‘data book’. This carefully tracks each input – whether human or material – into the construction of the screen, for quality and referral purposes. The name of each welder and their certification is recorded, for instance, along with the source and specification of the steel used. 

“As the screens are delivered, Kwatani service technicians will supervise their installation and commissioning on site, as part of our customer support,” says Schoepflin. “Our specialists will witness the cold commissioning – running without load – as well as hot commissioning with full load. We will confirm everything is running to specification and to customer expectations.”

Kwatani will conduct training of the mine staff in maintenance and troubleshooting, so that they can fulfil these essential duties independently. The mine will be able to source all the necessary spares from Kwatani, who will also send an engineer or technician to site to supervise and sign off on certain major tasks. 

Meeting delivery deadlines and avoiding penalties will require detailed logistical planning for the completed units, he notes. The screens will be delivered in batches to a South African port, and shipped as break bulk due to their size. Production of the screens is expected to be complete by early 2023. 

In response to the innovation imperative in the mining sector, Kwatani will use Electra Mining Africa 2022 – to be held at the Johannesburg Expo Centre from 5 to 9 September – as the ideal platform to cast the spotlight on its modern multi-slope screen design and the company’s strides in digital innovation.  

While multi-slope screens – generally known as ‘banana’ screens – have been available since the 1980s and are therefore not necessarily new to the market, Kwatani has in recent years ushered in a whole new approach to the design of these screens, says CEO Kim Schoepflin. 

“Traditionally, multi-slope screens have always been renowned for their high velocity,” she says. “While the high velocity translates into high capacity, the downside is the resultant screening inefficiency and the high wear rate of the panels, which in turn translates into high maintenance costs.”

At the top of these screens, explains Kwatani COO Kenny Mayhew-Ridgers, is usually a first slope with a deck angle of at least 34 degrees – allowing material velocities of over 4 metres per second – curving down to end at about 10 degrees. 

This traditional layout, however, is not always ideal for many operations today, as it calls for a much higher installation height. With a much flatter layout, the Kwatani design means that the installed height of the screen is far lower, translating into lower costs – both from a building and machine fabrication perspective.

“Banana screens have always been designed this way, and it became an industry norm,” says Mayhew-Ridgers. “Nobody really evaluated this traditional design, until recently when Kwatani, through its research and development, challenged the norm and adopted an innovative multi-slope design with great success.”

Kwatani can design its screens to perform efficiently at a lower building height and fit into existing screen infrastructure. The lower physical height of the screen also impacts the capital cost of complementary equipment such as pumps. “Because you have to pump at lower heights, you can therefore acquire smaller pumps, which means that the energy footprint is also much lower,” Schoepflin adds.  

Apart from its leading-edge multi-slope screen design, Kwatani will also showcase its advances in the digital space. Digital technologies, says Schoepflin, have the potential to unlock new ways of managing variability and enhancing productivity. The miniature version of the Kwatani multi-slope screen to be displayed at Electra Mining Africa will therefore be digitally enabled.

“We approach digitalisation in two ways. We believe that sensors are the starting point, as they are where data is created. Embedding sensors in plants, which in turn churn out large volumes of data for analysis, is increasingly attainable,” says Mayhew-Ridgers. 

“The second scenario is the cloud environment, which is gaining strong momentum across the industry. As mining companies digitally transform, they simultaneously expect greater control over their data with all the benefits of a cloud experience. At Electra Mining Africa, we will therefore showcase these two scenarios –sensors with a PLC/SCADA and control room environment, as well as a cloud solution,” adds Schoepflin. 

The digital picture, says Mayhew-Ridgers, is however bigger than these two scenarios. Leveraging digital solutions, mines can now plan and execute maintenance of their mission-critical assets better. Digitalisation empowers maintenance regimes by utilising collected data to monitor equipment health, diagnose faults, predict and troubleshoot failures well before they happen. 

“We will also highlight how the recent acquisition of Kwatani by Sandvik further advances our innovation drive. Leveraging Sandvik’s substantial experience in this field, Kwatani will further drive its digital offering, thus ushering in a new age of efficiency and winning the productivity and cost-control battle for our customers,” Schoepflin concludes. 

Namibia’s bustling mining scene is seeing an exciting expansion and technological innovation at a leading gold mining operation, with Kwatani supplying five mill discharge screens – all custom designed and manufactured at its Gauteng facilities.

Kim Schoepflin, CEO of Kwatani, says her company has a long history in Namibia and a strong footprint across various commodities there – including an established presence at this gold mine. It has worked with the engineering, procurement and construction (EPC) contractor and the end-customer for two to three years on conceptualising the optimal solution.

“The mine is gearing up to increase its production by 50%, to take advantage of the strong gold price,” says Schoepflin. “Our role was to ensure that our discharge screens meet their exact process requirements – with our efficiencies of up to 95% – while delivering mechanical integrity for minimal maintenance downtime.”

The expansion includes the installation of two latest-technology mills – a high-pressure grinding roll (HPGR) and a vertical mill – which will boost production while reducing energy demand. Kwatani’s mill discharge screens, each measuring 3 m wide by 8 m long, will handle the coarse and fine material from the HPGR and the vertical mill. The company will also supply three silo feeders of 1,2 m by 2,5 m in size, to feed material from the silo to conveyors.

“Our screen design optimises the retention time on the deck, allowing for better screening and stratification,” she says. “Due to the volume of slurry and water sprayed onto the screens, the added retention time assists with better drainage at lower cut points.” 

The coarse screens were designed at a decline, and feature a larger screening media aperture with higher amplitude and stroke. Together with lower speed, this achieves better screening efficiency for the coarser particles. The fine horizontal screens, with smaller aperture screening media for the finer feed, were designed with a higher speed and lower amplitude and stroke; this will optimise the screening efficiency of the finer feed to these screens.

She also highlights the attention paid to the isolation of the vibrating screens. In this case, Kwatani engineers selected rubber buffers, which have higher dynamic loads but are more suited to wet applications and screens with a heavier mass.

“The number and type of buffers were defined according to the mass of the screens,” says Schoepflin. “The selection of rubber buffers for larger screens also assists with start-up and shutdown time, allowing the screens to come to rest more effectively.”

For these five screens, Kwatani designed and supplied custom counter-balance frames to minimise the dynamic load to the plant infrastructure. The company’s screen technology includes designing its exciters in-house. This ensures that screens receive the necessary G-forces for optimal material stratification and screening, matching customers’ process requirements with the best possible efficiencies. 

“To make sure our screens cope with the high capacity demands of modern processing plants, we rigorously test all units in our in-house testing facility before dispatch,” she said. “These units began their journey to Namibia at the end of November 2021, and our team will support the commissioning when the customer requires.”

South Africa-based vibrating screen and feeder specialist Kwatani will soon add another installation to its extensive footprint in the Northern Cape, this time for a greenfields expansion of a new customer in the iron ore mining segment.

“We have over 1,000 screens, grizzlies and feeders in this important mining region, giving us a market share of about 95% of heavy-duty screening applications there,” says Jan Schoepflin, Kwatani’s general manager: sales and service. “With our well-established branch in Kathu, we are also able to assure our new customer of quick and highly competent service levels.”

The ore characteristics of iron ore demands mechanically robust screening equipment and Kwatani has built a name for itself in these applications, according to metallurgist Frengelina Mabotja, Kwatani’s head of sales for SADC. “Our equipment is engineered for tonnage and continuous throughput, without compromising efficiencies.”

Kwatani’s scope of work on the 700 tonne-per-hour dry processing plant includes a1,5 metre wide grizzly screen to remove fines from the run-of-mine material before it reports to secondary crushing and a 1.5 metre single deck scalping screen. The company will also install two 2,4 metre wide, double-deck sizing screens to separate material after secondary crushing, and five feeders to draw material from bins and stockpiles onto conveyor belts for feeding onto the downstream process.

“Our niche expertise allowed us to once again offer high performance sizing screens customised for this unique dry sizing application and optimise material separation by achieving the required cut size for the customer’s desired product size,” says Mabotja. “Our solution optimises the material separation while maximising efficiency and ensuring mechanical reliability for continuous and economical production.”

She highlights the depth of in-house experience – from both a metallurgical and mechanical approach– which allows Kwatani to assist the decision-making of customers on equipment choice and specifications. With 47 years in the vibrating screen and feeder business, the company can bring its myriad lessons in the field to bear on each project. 

“Through the work of our design team, supported by our manufacturing and testing facilities, we have ensured that the solution will be fit for purpose and reliable,” she says. “The customer was also able to visit our 17,000 square metre local manufacturing operation in Kempton Park regularly to see how we work, to check on fabrication progress and to witness the testing process.”

This level of engagement with customers builds their confidence in Kwatani’s ability, as they can experience first-hand the systematic, quality-controlled approach to design and manufacturing. The company’s extensive facility is ISO 9001:2015 certified. 

The equipment was completed on a tight deadline of 8 to 12 weeks, for delivery by year-end in line with the customer’s timeframe. 

“Our fully-equipped branch in the Northern Cape, staffed by specialists with decades of mining experience, will oversee the installation and commissioning of the equipment,” says Mabotja. “Our team will also schedule regular site visits to monitor on the equipment’s performance and condition, and advise on maintenance requirements.”

To underpin the reliable operation of all equipment supplied, Kwatani will also provide training for the customer’s maintenance personnel in the basic maintenance routines required. 

Business as usual is how Kim Schoepflin CEO of Kwatani describes the news of the closing date of the transaction whereby Sandvik Rock Processing Solutions and Kwatani signed an agreement for the multi-national Sandvik Group to acquire the shares of this 45-year-old leading vibrating screen and feeder Original Equipment Manufacturer (OEM). 

Schoepflin says when the exciting transaction, which was subject to regulatory approvals and customary conditions, was made known to the mining and materials handling industries earlier this year it was exceptionally well received by the markets, from both potential and existing customers. 

“Kwatani has operated its world class production facility in South Africa for more than 45 years, and both Sandvik and Kwatani are technology leaders so bringing our combined resources to customers will be of enormous benefit,” she says. 

“What is most significant for the South African industry is that the collaboration is aligned with our government’s industrialization strategy. Furthermore, Kwatani is known for its commitment to compliance with the South African Mining Charter and we are a proudly Level 2 B-BBEE company.” 

Add to this, and a game changing move for the South African economy is that the Kwatani facility is set to become the global engineering and manufacturing base for vibrating screens and feeders for both local and international customers. The internationally recognised Kwatani brand, with its promise of being engineered for tonnage, will remain unchanged and the Kwatani brand will continue to be used across Africa while products sold internationally will be sold through the Sandvik sales channels under the Kwatani product name.

Schoepflin says that also exciting for the market is that Sandvik will further develop the Kwatani vibrating equipment brand globally. “This will see increased access to the Kwatani product through Sandvik’s global distribution network and customers will benefit by having access to a vastly increased customer service network.”

“Sandvik will also, through its global technology resources, provide access to monitoring and automation processes as well as access to its extensive R&D facilities which include simulators.” 

This, Schoepflin says, will provide opportunities for driving efficiency arising from the advance of artificial intelligence in the Fourth Industrial Revolution and will significantly empower the process of cost effective customisation. 

About Sandvik Rock Processing Solutions 

Sandvik Rock Processing Solutions, one of four different business areas in the Sandvik Group, is a leading global supplier of equipment, service and technical solutions for the mining and construction industries. Its products and solutions are specifically used in crushing and screening, quarrying and breaking and demolition application. 

About Kwatani 

Kwatani is Africa’s leading Original Equipment Manufacturer (OEM) of custom-engineers vibrating equipment including screens and feeders to both local and international customers. This South African based company, with a proven track record of 45 years, operates a world class production facility in Johannesburg. 

Demonstrating its depth of local engineering expertise and technical capability, local vibrating screen specialist Kwatani has designed and fabricated a specialised spiral elevator for a mobile containerised sorting plant for a diamond mine in Australia.

Although not the first spiral elevator be produced by the company, this particular one was the first of its particular design to be engineered from scratch and manufactured by Kwatani.

Better known for its large, robust vibrating screens and feeders, the Kwatani 450 kg custom spiral elevator was an interesting contrast for the engineering team – but the results reflected the company’s usual standards of excellence. 

Within a timeline of just 10 weeks, the project combined first principles of physics with Kwatani’s decades of experience in custom design and manufacture.

“The client had very specific functional and dimensional requirements for this design, with the available space for installation being very constrained,” said Kwatani senior mechanical engineer Gideon de Villiers, who led the team in developing the two metre high spiral elevator. “We were also pleased to be able to meet the client’s throughput needs first time around with this specific design and build.”

The unit will convey up to 3.5 tonnes per hour of diamondiferous ore between sorters in a mobile containerised sorting plant, which is destined for a diamond mine in Australia. The material to be moved up the spiral elevator ranges in size from 5 mm to 30 mm. 

De Villiers highlights that Kwatani already has an established reputation with the sorter OEM, creating the necessary trust in Kwatani’s custom-engineering capability. 

“Our extensive knowledge on feeders and vibration dynamics placed us well to successfully tackle this innovation,” he says. “We started with the basic engineering calculations to clarify what dynamic movement we required, working through factors like planned tonnages, isolation of dynamic forces, friction value of ore, and motor orientation and direction.”

Designs were simulated using specialised software before Kwatani’s skilled team of artisan welders tackled the task of construction and platework. This included finite element analysis to identify areas of potential ‘hot spot’ stresses. 

Working with relatively light plates of 3 mm to 4,5 mm thickness, the elevator comprises S355 structural steel to cater for dynamic vibrations. The footprint was kept to around 700 mm, with two unbalanced motors at the base. 

“Due to the high value of the diamonds in the material, the structure also had to include static covers welded to the body, as well as maintenance doors with anti-tamper seals,” he says. 

Once fabrication was completed, the team embarked on a thorough testing programme lasting two weeks, conducted in Kwatani’s dedicated test laboratory. This allowed for the adjustment of various parameters, requiring close collaboration between the design and fabrication teams.