KWATANI SCALPERS TREBLE PANEL WEAR LIFE

As mines move towards using one large scalping screen between primary and secondary crushers – rather than a modular approach using multiple smaller screens – Kwatani has found ways to triple the panel life in these single mission-critical units.

According to Kenny Mayhew-Ridgers, chief operating officer of Kwatani, any downtime in this single-line stream would require the mine to store several hours of production. While some mines schedule regular weekly production halts during which an exciter or worn screen panels could be replaced, many operations are not so lenient, says Mayhew-Ridgers.

“The message from these mines is clear: the longer the scalper can run between maintenance interventions, the better,” he says. “Our research and development efforts, together with extensive testing in the field, have allowed us to extend the life of screen panels from eight weeks to over six months.”

While smaller screens use wire mesh screening media, Kwatani has evolved larger screens that use rubber or polyurethane screen panels. Although these panels present less open area, they deliver important advantages. 

“Key to the success of our design is our integrated approach – which matches the panel design with that of the scalping screen itself,” he says. “This allows us to achieve a balance between screening area, aperture layout and screen panel life – a result based on a sound understanding of screen dynamics.”

Whereas wire mesh undergoes rapid wear from abrasive materials, the rubber or polyurethane panels are more wear resistant and deliver longer life. The latter require gentler declines for effective stratification, but a key factor is the stiffness of the screen bed. 

“The stiffness of the supporting structure must go hand-in-hand with the screen panel design to achieve our required results,” he says. 

Polyurethane panels, while strong and lightweight, have screening apertures that tend to be too stiff for heavy-duty scalping applications. This leads to blinding. Rubber overcomes this problem, however, and also delivers improved wear life. 

Kwatani has also developed a panel replacement system – with a fastening mechanism on the underframe – that improves safety and saves time. 

SEAL DOORWAYS BEFORE WINTER BLUES HIT

With winter on the horizon, companies with large doorways that allow easy access will have to find a way of maintaining comfortable indoor temperatures to ensure productive working conditions.

Wim Dessing, sales executive at Apex Strip Curtains, and the South African pioneer of the use of flexible PVC strips in a number of industrial applications, says that it is important to deal with a reputable company when selecting the most appropriate option to do this.

Dessing’s company offers a range of solutions including the traditional Apex Strip Curtain which features the patented Balledge® design. 

“While general purpose strip curtains will certainly do the job in closing off a doorway and prevent the ingress of cold into a working area, it may not be the most appropriate solution for a particular application,” he says. 

Dessing urges companies to look at alternatives means of sealing doorways and says that the range of products available today cater for both application and budget requirements.

The days of just installing a roller shutter door are long over. The company manufactures a range of fast action roll-up and fold-up doors which are suitable for applications ranging from food preparation and the hospitality industry through to mining and manufacturing. 

All doors have been designed using quality materials and components to offer a product that is safe to operate, extremely rugged and an effective barrier. 

For example, the standard Traffic fold up door, which is ideally suited to provide exterior access in production plants, shipment areas and warehouses, is designed to resist wind loading of up to 50 km/hour. A custom model of the door is also available that can withstand speeds of up to 90 km/hour.

The Traffic door is manufactured from strong self-extinguishing Class 2 fabric which offers excellent thermal insulation and vision windows are incorporated into the panels. The supporting structure is of high quality galvanised steel. Installation is exceptionally quick and easy, because the support structure contains all the electric drive gear and a specialised mechanical counterbalancing system. 

Like other doors in the range, the Traffic door is controlled by an electric unit which complies with all IEC regulations and can be activated by any type of remote control equipment including photocells, pressure sensitive mats, movement detectors or induction loops. To facilitate safety, the door is fitted with a release lever that opens it from either side in the event of a power failure or malfunction.

Safety features have also been incorporated and continuity of operation is ensured by a set of back-up batteries housed close to the electrical control panel. The door has a sensor bar on its lower edge which, in the case of an accidental collision, opens the door immediately no matter what stage in its cycle.

Another fast action roll-up door in the range is the Sector, a panel and window model, which uses the same counterbalancing system. This has an extension spring activated by a release lever to facilitate semi-automatic re-opening. 

“All the doors are engineered for extensive opening and closing actions, and require virtually no maintenance,” Dessing says. “However, it is vital that the correct door be selected and factors such as doorway size and the type and volume of traffic moving through this opening must be considered in the purchasing decision.”

Apex Strip Curtains provides a technical information service to assist companies in selecting the most appropriate door. Installation and commissioning is also part of the package.

FLSMIDTH HIGH DENSITY THICKENERS DOUBLE MINE OUTPUT

When one of the world’s largest copper and cobalt producers wanted to double its production rates, it chose FLSmidth to provide a thickener solution that included six of its proven high density thickeners. The order was placed in 2020, and delivery has been completed. 

The mine, located in the Democratic Republic of Congo (DRC), already had FLSmidth thickeners on site, and was satisfied with their performance. According to FLSmidth general manager projects and account sales Howard Areington, the company’s proposal for the mine’s expanded requirements was based on testwork to confirm the characteristics of the material that would be treated. 

“The tests confirmed that we could use a similar design to what we had installed on the mine some years previously,” he says. “This solution included six counter current decantation (CCD) thickeners and one pre-leach thickener, each measuring 31 metres in diameter.”

These units deliver high solids underflow to optimise the recovery of dissolved metals. In addition to the steeper floor slope, these FLSmidth thickeners were designed with a high torque ring gear drive design, with high tolerances that make for minimal maintenance over long periods of time.

“Our high density thickener design ensures consistently high underflow densities which allows the operator to sustain high production rates and better recoveries,” he says. 

These CCD thickeners are manufactured from LDX2101 duplex stainless steel. This provides mechanical benefits without compromising chemical resistance, allowing the mass of each unit to be reduced. The pre-leach thickener, which was not exposed to corrosive conditions, is constructed from carbon steel. 

“We also designed and supplied five impurities removal thickeners, which are high rate thickeners, also in LDX2101 stainless steel,” he says. “The sizes of these units ranged from 20 to 30 metre in diameter.”

Fabrication of the equipment was done in South Africa, while accommodating the demands of the Covid-19 lockdown, which required careful planning and flexibility. With components and platework delivered to site, the welding and construction was conducted by the mine with installation assistance from FLSmidth and its agent in the region. 

BOOYCO EXPANDS ITS COAL FOOTPRINT AS LEVEL 9 LOOMS

Coal mines were among the first customers of proximity detection system (PDS) specialist Booyco Electronics, and the company continues to grow its footprint in this sector as mines work towards Level 9 compliance.

According to Booyco Electronics CEO Anton Lourens, the scale of recent orders from underground collieries and opencast operations are testament to the company’s leadership in the sector. 

“We support an extensive population of our proximity detection equipment on trackless mining machines (TMMs) in coal mines, and expect to see enthusiastic take-up of our new-generation Booyco CXS product,” says Lourens. He highlights that the customer base includes not only the Mpumalanga coalfields, but also those in KwaZulu-Natal province – supported by the company’s network of branches including Witbank and Richards Bay. 

Regulations currently demand that any electrically powered TMM in an underground mine must be equipped with a PDS, but many coal operations have a combination of diesel and electric units. He emphasises that the regulatory framework will soon enforce Level 9 requirements – with more advanced collision avoidance capability – for both diesel and electric TMMs.

“We are working closely with many OEMs and mining customers on aligning and testing our respective equipment for Level 9 compliance,” he says. “It should be remembered, however, that the industry still has considerable work to do on the application of PDS technology to surface diesel TMMs, which pose a range of technical challenges.”

An active participant in the mining industry’s Earth Moving Equipment Safety Round Table (EMESRT), Booyco Electronics collaborates extensively with stakeholders to support mines’ safety and compliance efforts. 

“Coal mines have a key role to play in the testing and application of collision avoidance systems, as the industry upgrades to ever-more effective safety protocols,” says Lourens. “The Booyco CXS consolidates all we have learnt in our 15 years in business, taking that vital step from a warning system to a fully-fledged collision avoidance system.”

He highlights that the Booyco CXS retains the intrinsically safe technology of previous generations, making it more cost effective and generally easier to manage. “The common alternative to intrinsically safe equipment is for suppliers to add a flameproof enclosure to house the PDS, which tends to be heavy and impractical,” he says.

Another contribution to safety and productivity is the Booyco Electronics Asset Management System (BEAMS) – a central information hub for a mine’s PDS assets. Centralising information from PDS hardware and monitoring devices, BEAMS enhances operations by identifying patterns of unsafe behaviour that can be promptly addressed.

SLURRYSUCKER SUCCEEDS WHERE OLD METHODS FAIL

Integrated Pump Rental’s innovative SlurrySucker desilting barge is successfully cleaning a large process dam for a coal mine in Mpumalanga, after past attempts by numerous contractors had failed. 

The dam – at a mine in the Delmas area – measures a substantial 300 metres by 100 metres in size, with a six metre depth. It was unable to function effectively as it had become 90% filled with coal slurry from the processing plant. Ruaan Venter, rental development manager at Integrated Pump Rental, says the pond is also lined with a geomembrane to prevent the coal slurry from contaminating the groundwater.

“Manual excavation methods had been tried by previous contractors, but these could not efficiently move the required volume of sediment,” says Venter. “In fact, some attempts made matters worse by damaging the environmentally important membrane under the pond. In addition, extensive reed growth in the dam also hampered the desilting efforts.”

By contrast, the application of the SlurrySucker was able to meet the safety priorities of the mine while cost effectively removing the slurry. Operating the barge remotely from a defined distance away from the dam’s edge is much safer than having personnel or equipment on the dam itself, he says. Operators also use a buddy system with a harness for added safety. Extensive training of operators was also required by the mine before work began.

“We were able to float the SlurrySucker on those parts of the dam with sufficient water, while also employing hydro-mining on the drier areas,” he says. “This allowed our high-solids pumps to dredge quickly and cost effectively over the whole area of the dam.”

Two monitoring guns, each fed by a 7-bar high pressure discharge hose, are blasting the drier slurry towards the discharge point. Specialised pumps with chopper-impellers are employed, which can deal with the dislodged reeds without becoming clogged. After setting up on site in December 2020, Integrated Pump Rental is expected to complete the slurry removal process by the second quarter of 2021, says Venter.

RAISING BENEFICIATION EFFICIENCIES IN COAL

With South Africa now working hard to contain the cost of its coal-fired power generation, efficiencies are vital throughout the value chain – not least in beneficiation.

This means the continuous improvement in coal beneficiation technology and regular equipment upgrades in plants will become more important, according to MBE Minerals SA managing director Johannes Kottmann. With over a century of experience in the coal sector, MBE Minerals SA has built up a wide footprint of vibrating screens in Africa for sizing, scalping, dewatering and media recovery. It also provides destoning solutions to customers.

“Among the company’s innovations is the side plate mounted drive, a much lighter option to using vibrator motors,” says Kottmann. “The screens can also be supplied with vibrator motors if necessary, while resonance screens offer the added benefit of lower power consumption.”

All types of screening surfaces can be accommodated, with each screen incorporating mechanical design features such as vibration dampening, side plates, cross members and the appropriate feed and discharge chutes.

He highlights that MBE Minerals is actively engaged with developments in coal beneficiation technology through its international network, including the MBE Coal and Minerals’ Research and Development Centre in Cologne, Germany. 

“This centre consults with customers globally in terms of optimum processing solutions, with the support of an in-house laboratory and pilot test work facilities,” he says. The centre also offers customer training, which can range from general mineral processing to maintenance of MBE Minerals’ equipment. 

In addition to designing, engineering and supplying equipment, MBE Minerals conducts projects on a turnkey or EPC basis, he notes; the company can also operate complete coal processing plants. It is particularly well known for its BATAC® jig technology, which delivers high separation efficiencies and improved product quality, as well as high availability and throughput. This technology’s ease of operation, robust design and economical maintenance cost have also been important factors in its success.

The company developed the BATAC® jig to overcome the limitations of early stratification technologies, which achieved separation either by moving the entire jigging bed screen or through water pulsation generated in an air chamber beside the jigging bed. 

“The separation accuracy of BATAC® jigs is due to electronic control of the air pulse generator and sensing of the thickness and densities of the material layers being separated,” he says. The under-bed pulsated BATAC® jig has proved ideal for coarse applications from 150 mm down to fine coal in the 10 to 0,5 mm size range, with throughput rates of between 100 and 1,200 tph. 

MBE Minerals has also developed a reliable and economical solution in destoning raw coal – the ROMJIG® – which has produced impressive results in extensive testing around the world. It achieves an overall reduction in the stone handled, says Kottmann, and there are indications of a lower percentage of refuse in the washery feed.

“This allows costs to be saved in a number of areas, such as reduced wear on machinery and transporting equipment, less grain degradation, and less dust and slurry,” he says. “It also means that flocculation consumption is reduced, along with flotation agents in downstream fines recovery circuits.” 

The range of vibrating screens manufactured by the company includes dimensions up to 3,6 metres in width and 6,75 metres in length; they come in single or double deck configuration and with either circular or linear motion. They have been operating in the African mining industry for the past 40 years.

“We ensure that each application, whether greenfields or brownfields, is carefully assessed in conjunction with the customer, during a comprehensive engagement process to determine the optimum solution,” he says. Services available include detailed engineering, feasibility studies, raw material testing, financing concepts, erection and commissioning. 

Components – as well as automation and process control equipment – can be supplied and installed for complete plants and systems. Measures to modernise plants or improve capacity can also be proposed. The company’s scope of services includes personnel training, along with pre- and after-sales services and support.

NEW GENERATION CAVEX® HYDROCYCLONE BOOSTS THROUGHPUT, WEAR LIFE

Weir Minerals has launched its Cavex® 2 hydrocyclone, which is an exciting improvement on the successful Cavex® hydrocyclone launched in the 1990s.

The design of the new generation model ensures a step-change in separation performance and reduced turbulence, says Lerato Ramanala, product manager hydrocyclones for Africa and the Middle East at Weir Minerals Africa. 

“The Cavex 2 hydrocyclone improves the design of the 360⁰ laminar spiral inlet, which delivered a step-change in separation performance and reduced turbulence,” says Ramanala. “The new design includes the LIG+ advanced laminar spiral inlet and a longer feed chamber, further reducing turbulence and classifying a higher volume of feed slurry.”

She highlights that the Cavex® 2 has the same footprint as the original Cavex® hydrocyclone – and competitor cyclones – so retrofitting is a simple process. Customers can benefit not only from the increased throughput capacity but through operational flexibility by being able to take hydrocyclones offline for maintenance without affecting process flow. 

Results from Cavex® 2 hydrocyclones installed across the globe have shown that it maximises plant recovery by reducing the quantity of misclassified particles; the alpha parameter improves by an average of 10% while the bypass improves by an average of over 15%. Fewer fines are returned to the mill, and mines can reduce their carbon footprint by consuming less energy for small particle reduction.

The Cavex® 2 accommodates the company’s in-house Synertrex® industrial internet of things (IIOT) technology, which detects sub-optimal operating conditions like roping in real time and improves overall performance. This aligns with mining industry efforts to leverage digital technology to create mines of the future. 

The shape of the liner has also been improved leading to longer life, less downtime for maintenance and lower total cost of ownership. Liners are available in a range of materials including industry‑leading Linatex® premium rubber and other robust Weir Minerals natural rubbers such as R55®.

MULTOTEC LEADS THE WAY IN COMPOSITE LINERS FOR LARGE SAG MILLS

As the mining industry moves to larger semi-autogenous grinding (SAG) mills for higher productivity, Multotec is developing and applying innovative liner designs to optimise liner performance, mill efficiency and liner wear life.

“Our strong analysis capabilities in the design process – including discrete element analysis (DEM) and finite element analysis (FEA) – allow us to continuously evolve the application of our composite liners,” says Sam Hearn, global sales and business development manager, Multotec. 

Hearn highlights how Multotec uses DEM software to simulate the interaction between the mill charge and the liners, and to evaluate liner profile over the life of the liner. 

“The DEM analysis considers a range of variables such as the ore’s bond work index, its specific gravity, the size of the grinding media, the mill speed and the slurry density,” he says. “Sophisticated simulation capability allows us to accurately model the performance and wear of our mill liners. This includes predicting the liners’ wear life, to avoid unscheduled downtime and to extend the time between replacements.”

Emphasising that no two mill liner applications are identical, Hearn says that this simulation can guide very specific refinements in the liner design for each customer. A detailed understanding of the operating conditions is vital to ensure that the final solution delivers optimal results.

He notes that the traditional use of steel liners in large SAG mills presents a number of challenges. For instance, there may be bending stress inside the steel liner due to inexact fitting on the mill’s curved surface, and the higher rigidity of steel compared to rubber makes it less than optimal for absorbing the energy of rock material inside the mill.

“This is where our composite liners come into their own,” he says. “These innovative liners combine the impact resistance of Hardox 500 steel inserts and the absorption capacity of our specially formulated wear-resistant rubber compound. Through the simulation, the structural integrity of the liners can be verified, while the geometric layout of the liners can be optimised.”

The composite liners are locally manufactured at Multotec’s extensive facility in Spartan, Gauteng, in an advanced process that includes its unique submerged cutting technique to preserve the surface hardness of the liners.

“We combine our innovative design capacity with the latest tooling capability and production technology for large-scale manufacture,” says Hearn. Following the design and manufacturing process, Multotec conducts field trials to compare to the relative performance of composite liners and steel liners. 

“We are confident that, given our product improvement processes and simulation ability, the wear‑life of our liners will achieve and often exceed expectations,” he says.

CONCOR COMPLETES HIGHEST RESIDENTIAL BLOCK IN MOTHER CITY

Cape Town has just seen the successful completion by Concor of the tallest residential block in the city area – fronted by a carefully preserved, century-old façade onto one of the trendiest streets in town. 

The 16 On Bree project is remarkable not just for its size – it transforms an old two-storey block into a modern 38-floor luxury development – but its complexity. According to Concor Western Cape senior contracts manager Collin Morilly, an early challenge was the preservation of the fragile heritage façade.

“The 16 metre high wall was built not of concrete but of rock, clay and lime, so it needed very gentle treatment and firm support,” says Morilly. “We erected a specially designed structural steel brace that would support the wall and prevent any structural failure while it was cut free from the rest of the building, which had to be demolished.”

A concrete ground beam was also cast along the base of the façade to act as a counterweight and prevent any movement. As the new structure was built, it was stitched in with the braced façade until finally the brace could be removed. There were also three other heritage walls within the building – standing in a U-shape – which were preserved during the construction process.

“The project also had to be implemented in the highly space-constrained city centre, with busy roads on all boundaries of the site,” he says. “This meant there was almost no laydown area for materials and equipment, and we had to ensure an uninterrupted flow of vehicular and pedestrian traffic.”

This was a significant achievement given the scale of the project, which consumed 21,000 m3 of concrete, 1,650 tonnes of reinforcing bar and 650,000 bricks. The new height of the building required the placement of 40 concrete foundation piles. Tower cranes had to be carefully managed to lift and place materials, a task made more difficult by the high winds for which the Cape is known, especially in summer. 

“Then came the unexpected disruption of work due to the Covid-19 pandemic,” he says. “We were soon able to get back to work after the initial lockdown, but this required extra vigilance and discipline because of the number of workers in such a confined space.”

Having about 900 people on a relatively small footprint over multiple floors meant that Covid-19 protocols had to be strictly implemented, based on a thorough understanding by all employees and subcontractors of the infection risks. 

“Social distancing was a particularly onerous aspect for us to adhere to, as the nature of construction demands that workers operate in teams and groups,” he says. “For example, a team of tilers must work in an apartment together, but the regulated social distance must be observed. This required that fewer workers be allowed into an area, which reduced overall productivity.”

Nonetheless, work proceeded apace to roll out the apartments efficiently and to the highest standard of workmanship. Drawing on the expertise of its trusted subcontractors, Concor’s experienced supervisors kept a close eye on the pace and quality of work, with at least four foremen looking after each floor. 

“We run our projects according to our SANS 10400 and ISO 9001 accreditation, and this means close management of the quality assurance and quality control process,” says Morilly. “Our systems included the SnagR snagging software to accurately record and close out snags timeously, and the Synergy document control software to facilitate timeous issue of information, tracking and recording.”

The Finishes Matrices system was also employed, indicating the level and the apartment in which each of the trades should be working every day. 

The result has been an elegant structure gracing Cape Town’s city skyline, rising 120 metres from street level and comprising 380 upmarket apartments. The future may hold scope for further residential units, making use of space currently used for the parking areas. To make this possible, the parking floor-to-ceiling heights were designed to the same dimensions – 2,9 metres – as the apartment levels. 

CONCOR LEVERAGES GLOBAL STANDARDS TO LEAD IN MINING

Meeting international standards is not an end-goal but an essential step in continuously raising the performance bar, according to Concor Mining Services HSE & training manager, Neil Fourie.

With its quality, environmental management, and occupational health and safety management system certifications recently renewed, Concor has underpinned its world-class status, says Fourie.

“These standards represent the life blood of our business, as customers rely on our management processes to provide them with the highest quality of service,” he says. “Our certification in terms of ISO 45001:2018, ISO 9001:2015 and ISO 14001:2015 gives them the peace of mind that we operate a management system aligned to global best practice.”

He emphasises that a key element of the ISO standards is the principle of effective control and continuous improvement to company procedures and processes. 

“Each year that we operate with these certifications in place, our management system matures and improves,” he says. “This guides us into deeper levels of auditing, which in turn drives our efforts to become better at everything we do – including raising our productivity and compliance.”

Good systems provide a backbone for the business, he notes, allowing the management team to focus on the operations and on smooth implementation of projects. This is increasingly vital in a competitive market, where managers on site must be able to tackle their important tasks in a systematic and methodical fashion.

One of the certification requirements is that internal audits are conducted on a regular basis to determine the effectiveness of our systems. “The internal audits are conducted at various levels and this interaction with our employees also has its own benefits, according to Concor Mining Services quality manager, Liz Diederichs. Far from being simply administrative checklist exercises, internal audits create valuable opportunities for engagement, coaching of employees at all levels, raising awareness, and often with inputs from the auditees opportunities for improvement.

“On a quality management audit, for instance, we check that all systems on a project are understood, implemented and maintained, allowing us to give considerable support to site management,” says Diederichs. She highlights the collaborative culture within Concor Mining Services, where all the relevant personnel are involved in the audits and the formulation of procedures. 

“All activities and tasks are discussed in detail, ensuring that employees buy into the process of creating the procedures that ensure the best practice is followed,” she says. 

Fourie notes that having a well-entrenched integrated management system that is aligned to international standards streamlines project turnaround times. On every new site that must be established, clear guidelines are in place for starting up and operating, so everyone can see what needs to be done.

“This also makes it easier to on-board new employees and ensure that they become productive as quickly as possible,” he says. “This adds to our adaptability and agility on projects, enhancing our cost competitiveness, workmanship and reliability in terms of meeting deadlines.”

As managers, specialists and professionals move between sites where projects are already underway, they can also slot into the workflow more easily as the systems and record keeping provide a detailed picture of planned and completed tasks.

“Having our own system based on international standards improves our interaction with the client too,” he says. “It allows us to easily align to the client’s requirements, or to seamlessly apply our own world-class system without compromising continuity.”

Concor Mining Services sets well defined objectives and targets to include from strategic, operational and functional through to health, safety and environmental issues like energy efficiency, carbon footprint, and equipment maintenance. Applying its standards-based integrated management system, the company has over the past five years maintained a zero-fatality rate and a lost-time injury rate of 0,00%, he says.

Installation of LED lighting at company facilities and rain harvesting at engineering workshops are among the energy and environmental interventions, while improved maintenance has been extending equipment lifespan and reducing the carbon footprint. 

Learning from health, safety, environmental and operational incidents has been an important feature in the continuous improvement journey with in-depth investigations, root-cause analysis and corrective action helping to eliminate the causes of non-conformances. The integration of Concor Mining Services’ management systems allows this learning to be effectively shared across the organisation.

“Our formalised systems also allow us to better monitor, measure, analyse our processes and communicate the status of our progress to all employees, so that there is a good understanding of their contribution towards achieving our targets,” says Diederichs.