TRAFO TAKES KEY ROLE IN GLOBAL BREWER’S GAUTENG UPGRADE

Dry-type transformer specialist Trafo Power Solutions has delivered transformers and other electrical upgrades for a global beer maker’s expanded facility in Gauteng.

In addition to the supply of three transformers, the customer was also looking for a partner who would interface with the suppliers of various aspects of electrical equipment, according to Trafo Power Solutions managing director David Claassen. Trafo has therefore interacted closely with the customer’s Europe-based engineering team on the one hand, and with local electrical contractors on the other.

Meeting high-pressure deadlines, three transformers were designed, supplied and commissioned. These included a 1250 kVA and a 1600 kVA unit – both with 11kV to 400 V capacity – as well as a 2000 kVA unit for 11 kV to 690 V application.

“These transformers all comply with the European Directive on Efficiency and are the lowest-loss dry-type transformers available,” Claassen says. “This was the customer’s specification, as they place strong priority on energy efficiency worldwide.”

Also, in the scope of work was medium voltage switchgear, including two ring-main units (RMUs) with one a three-way and the other a four-way.

“We modified the RMU’s in line with the customer’s requirement, including a battery-tripping unit (BTU) on each,” he says. “This ensures there is power available regardless of the condition of the circuit breaker.”

As a brownfield project, there was considerable adaptation of design to suit the plant configuration. Instrumentation was located on a raised base, for instance, where voltage transformers and current transformers were installed for monitoring each RMU.

“We also supplied three very specialised distribution boards (DBs) between the low voltage transformers and the new sections of the plant and new brewhouse,” he says. “This non-standard design has a modular type assembly conforming to EIC 61439 and EIC 61641.”

This provides the highest level of safety and can be supplied by only a few manufacturers in South Africa. The DBs, which are fully-tested for IEC 61641 (Internal Arc Fault), incorporate 2500 Amp incomers, distributing through various feeder circuits to the rest of the plant. Two of the DBs are 400 V and the third is 690 V.

“Another non-standard aspect of the DB supply was its Form 4A design, so that each compartment is separate,” Claassen says.

He highlighted the company’s in-house capacity to provide complete solutions within tight deadlines. In this case, the design, manufacture, delivery and commissioning were achieved in just three months. Installation was also co-ordinated with plant shutdown schedules to avoid costly downtime.

“We develop non-standard solutions where these are required, and take responsibility for integration, compatibility, quality and timeframes,” he says.

AFRISAM URBAN QUARRY AND PLANT DEFINE GOOD NEIGHBOURLINESS

Increasingly hemmed in by urban development, AfriSam’s Jukskei quarry and readymix plant have been applying ever more stringent controls and standards to remain a friendly neighbour.

When the Jukskei quarry began operation some seven decades ago, its location was decidedly rural. However, the surrounding area of Midrand developed rapidly, and in the last 10 to 20 years in particular, various neighbours have closed in around the Jukskei aggregate and readymix operation.

“Today, we are surrounded by residential, commercial and industrial developments,” Zielas Du Preez, regional manager for AfriSam’s Gauteng Aggregates Operations, says. “This process, alongside the changes in environmental regulations, means that we are constantly improving the way we work.”

Noise, dust, blasting and water quality are among the most important areas of focus. To minimise the impact on surrounding areas, noise monitoring is regularly conducted. Measuring points around the operation feedback information on how noise is being dissipated. The data populates an annual survey against which performance can be checked.

With the crushing of blasted granite into various aggregate products, and the constant movement of trucks and other equipment, dust is inevitable. A number of strategies to control dust are applied, Du Preez says. These range from sprays inside the high speed crushers, activated on start-up, to water spray systems along the roadways to suppress air-borne dust.

This success is measured with the monthly analysis of Dust Fallout Buckets, strategically placed in numerous positions around the operation. The collection and analysis of these buckets are performed by an independent consulting group.

Monitoring of water quality is also critical, both upstream and downstream of the pit. This is done at seven sample points, ensuring that any seepage from the quarry is not negatively affecting water quality.

Controlling blasts in the quarry leverages the latest technologies to keep noise, vibration and other impacts low. He notes that electronic blasting has revolutionised the quest for more effective and better controlled blasts.

“Using electronic blasting technology and blast planning software, we can simulate each blast within optimal parameters,” he says. “We keep air blast, vibration and fly rock to a minimum, while still achieving our required fragmentation for the crushers.”

There is even a public engagement element to the blasting programme, where neighbouring properties are kept informed through a roll-call list. In pursuit of safety, AfriSam also engaged with the Helipad next door to declare the quarry area a no-fly zone during blasting.

Du Preez highlights that extra security measures have been applied in the quarry, including lighting and surveillance– as human settlements encroach ever closer.

CHRYSO HELPS SECURE FUTURE OF KARIBA DAM

The multi-million Euro engineering project to reshape the plunge pool at the base of the Kariba Dam wall incorporates the use of CHRYSO’s leading concrete admixtures to ensure optimal results.

Working closely with main contractor Razel-Bec is Mart Solutions, the Zambian distributor for CHRYSO® Southern Africa.

“Any large and complex project like this one demands ongoing collaboration, which started about two years before the concrete work began in October 2019,” says Mart Solutions director Martie Coulson. “Teamwork is vital between Mart Solutions, CHRYSO® and Razel-Bec to ensure the specified concrete mixes are achieved to the consultants’ exacting standards.”

The world-class project at Kariba Dam will see the building of a temporary coffer dam downstream of the main wall, allowing the deep plunge pool to be drained, reshaped and stabilised. This will reduce the backward scour in the pool, created by water released by sluices in the dam wall; the concern is that this scouring is edging towards the dam foundations.

The innovative admixture CHRYSO® Aquabeton ZA is playing a key role in allowing concrete to be placed underwater, to create a foundation for the coffer dam’s seven piers.

“This highly specialised admixture assists in minimising washout and segregation of fresh concrete when placed underwater,” Coulson says.

Among the range of CHRYSO solutions provided by Mart Solutions is CHRYSO® Omega 162 superplasticer, which is an important component of the concrete mix design for the seven piers. These large pier structures will range from 250 tonnes to 700 tonnes in weight. The first of these, currently under construction, will measure 5,5 metres tall when complete.

“CHRYSO® Omega 162 reduces the need to add extra water, and so increases the durability of concrete,” she explains. “This admixture also improves cohesion and lowers viscosity in the concrete mix, leading to improved homogeneity and superior off-shutter finishes.”

CHRYSO® Fuge B, which is a pore-blocking permeability reducer for mass concrete, is also being used. This reduces the size of the capillaries, thereby almost completely eliminating the penetration of water under pressure. This is important for the piers on this project as they are constantly in contact with water. The piers are being slip-formed as hollow structures, from a specially-built rig in the Zambezi River. When the piers have achieved the minimum required height, they are floated into position, secured to the foundation and filled with concrete.

Facilitating the release of formwork from the concrete piers is CHRYSO® DEM S, a versatile mould-release oil for timber or steel. Mart Solutions is also supplying the Kariba project with construction chemicals from CHRYSO’s a.b.e. range. The polymer bonding liquid a.b.e. Duralatex is applied to the cone holes in the piers, and these holes are then filled with a.b.e. Duragrout – a non-shrink grout for sealing.

SUPPORT CONTRACTS SHOW KWATANI’S WORLD-CLASS EXPERTISE

Maintenance contracts are an ever-more popular way for mines to ensure uptime on critical equipment; Kwatani should know, as it has customised contracts in place to service over 500 of its machines in the Northern Cape alone.

“Vibrating screens are critical to a mine’s material flow, which is its life blood,” says Kwatani CEO Kim Schoepflin. “This requires OEMs to be experts, not just in design and manufacture, but in service support and maintenance.”

As a leading local OEM, Kwatani has seen mines gradually embrace the value of maintenance contracts to avoid costly downtime. One of its contracts covers about 400 screens on a single mining operation. The range of its contracts extends to various commodities, from hard materials like iron ore and manganese to soft material such as coal. In one coal operation in Limpopo, Kwatani has contracted to service 160 of its machines.

Schoepflin highlights how regular, expert maintenance is vital for mines to achieve the lowest cost per ton in their production process. However, she warns that these contracts can only be conducted responsibly and effectively with the right level of knowledge and experience.

“With our depth of know-how gathered over more than 40 years, we understand exactly what inspections and critical replacement need to be done and when,” she says. “As importantly, we know how to conduct this work cost effectively.”

Accurate costing of maintenance contracts can only be based on a firm foundation of expertise, especially when contracts invoke penalties due to breakdowns. Kwatani’s experience in the field ensures that the requirements of its maintenance contracts are met. This allows the company to offer a range of financial models to customers when they consider such contracts.

“We are so confident of the quality and reliability of our vibrating screens and feeders that some customers pay us a cost-per-tonne rate to maintain them,” she says. “We design, manufacture, install and commission according to their requirements, and then we take financial responsibility for keeping them fully operational.”

Long-term contracts often also include a commitment to improve and enhance the performance of the screens over time. To do this work professionally requires qualified service teams who are supported by solid engineering teams. Kwatani has developed these resources locally over more than four decades, and continuously develops skills in-house, alongside the various management systems to ensure such skills are available timeously to the customer.

“In addition to training and employing local people for a service role at our branches, we also collaborate with mining customers to empower their locally based suppliers where this is feasible,” says Schoepflin.

She highlights Kwatani’s solution-orientated approach, combining the company’s expertise in its screening technology with the customer’s specific needs and resources.

MAJUBA ASH FACILITY GIVES 2020 A GOOD START FOR CONCOR

Concor has kicked off the year strongly, winning a significant Eskom contract for the extension of Majuba Power Station’s Ash Disposal Facility (ADF).

“This award signals the faith of the market in Concor’s stability, depth of expertise and engineering heritage,” says newly appointed Concor CEO Lucas Tseki. “As always, there is considerable urgency to complete this project. We look forward to completing it on time and on budget with our well-established commitment to safety and project delivery excellence.”

While power stations are generally designed for a life of around 50 years, support facilities like ADFs are often built in phases to optimise initial capital costs. The design for this ADF extension has also considered the changes in environmental legislation.

The contract secured by Concor includes three lined ash platforms and two lined rehabilitation dams; each of these requires subsoil drainage systems, intakes and spillways. The scope of work also includes clearing, bulk earthworks and embankment construction required for the new ash deposition liner terrace, with a subsoil herringbone drainage network.

In addition to constructing a liner system to the terrace area, Concor will install a leachate collection network and system draining to a pollution control dam. The whole contract will include various associated access and other civil works, including extending the ash conveyor route canals on the existing ADF.

The liner systems for the ash facility and the various dams comprise 300 mm of clay as a primary impermeable layer, with a 1,5 mm HDPE geomembrane liner as a barrier. For the ADF, this will be topped with a 300 mm screened coarse ash ballast or protection layer, while in the dams it will be ballasted with a 300 mm layer of cement-stabilised sand and topped with Armorflex blocks.

The contract will involve over 1,3 million cubic metres of bulk earthworks, almost 540,000 square metres of HDPE lining, 11,600 metres of HDPE drainage piping and 14,000 cubic metres of concrete.

“This type of project amply demonstrates Concor’s capability, expertise and indeed capacity as South Africa’s leading black-owned infrastructure and construction services company,” says Tseki. “Our order book for the year is looking positive, and we are hoping to secure a number of important contracts still to be adjudicated.”

FILTER PRESS SAVES WATER, REDUCES IMPACT

A Limpopo chrome mine faced various risks in disposing of its tailings and called Multotec for a solution.

The chrome operation was aware of the challenges that a traditional tailings storage facility (TSF) could create, according to Multotec Process Equipment senior process engineer Khathutshelo Mutshinyalo. These include the large footprint of a tailings dam, the expense of lining the tailings dam and the environmental and social impacts.

“The mine management was keen to conserve scarce water resources by avoiding evaporation,” Mutshinyalo says. “They also wanted to prevent any potential groundwater contamination that might result from solution seepage. There was also the local community to consider, to which a normal TSF could present a risk.”

Multotec was able to explore the full range of its dewatering solutions before recommending the most suitable one for this application, he says.

The filter press technology was the chosen option, as it was shown to meet the duty requirements in the most cost effective manner. As a well-proven mechanical dewatering strategy, the filter press was able to immediately recover about 80% of the clean water in the slurry.

“The cake that is left from the tailings after water removal is then easily moved by conveyor to a dump area,” Mutshinyalo explains. “This dump is much simpler and safer to manage than a tailings dam.”

The solution facilitates short cycle times, less wear on consumables and lower power consumption. The cakes are also easily released from the cloth and leave little residue behind on the cloth. He highlights that the process of reaching the selected solution was driven by thorough investigation, extensive test work, and many years of experience in the field. It always begins with a detailed understanding of the conditions that exist at the site, as well as the customer’s priorities.

“With the support of the research team at our testing facilities in Spartan, we were able to test the behaviour of the customer’s slurry samples with various Multotec solutions,” Mutshinyalo says. “This allowed us to confirm not only the best technology for the application, but also to innovate our equipment for optimal results.”

In this case, the abrasive impact of the tailings material was one of the key factors to be accommodated. While the filter press was proven to be the most effective solution, there was still considerable wear experienced by the filter cloth in the press.

“Combining our field experience and metallurgical expertise, we looked more closely at possible innovations for this aspect of the equipment,” he says. “We developed an improvement that would better protect the high-wearing areas of the filter cloth and deliver longer wear life.”

The detailed preparation behind this solution, and Multotec’s practical expertise in installing and maintaining its equipment, meant that final commissioning on site could be done without delay.

Mutshinyalo notes another recent application of filter press technology was in coal tailings, this time for a coal mine in the Mpumalanga area. Test work was again effectively used to find the solution best suited to the application.

“Here, we needed the filter press to operate in demanding conditions including a high tonnage throughput,” he says. “Once again, the focus was on innovation where we customised the filter cloth to improve its rigidity and life.”

The result was that the cycle life per cloth was doubled based on typical tailings applications – a considerable improvement in the wear life. Apart from the robustness of the filter press, the feed arrangement and process control were optimised to suit the process.

In addition to these applications, Multotec has also applied filter press solutions to copper sulphide, copper oxide and gold sludge applications. The company’s range of equipment and depth of technical expertise allows turnkey solutions which include the various items of auxiliary equipment around the filter press.

“Our branch infrastructure and network around the country gives us a quick response capability with our customers,” he says. “We are always mindful that – alongside the optimal solution – customers need quick action by all partners to keep operations running smoothly.”

GET SMART WITH ROLL-UP DOORS THAT RESET THEMSELVES

Businesses are driven to maintain a balance between safety and productivity. Access between areas within a facility and between the facility and its exterior plays a large part in achieving an optimum balance between these two factors.

“The well-being of personnel and suppliers is extremely important and plays a defining role in complementing the motivation of people in the workplace. The high-tech Smart Reset roll-up doors from Apex Strip Curtains & Doors provide safe and rapid access as well as effective insulation in production plants, retail facilities, warehouses and shipment areas,” Wim Dessing, sales executive at Apex Strip Curtains & Doors, says.

The engineering behind these heavy duty automatic doors is based on years of experience in the market. Manufactured with CE certification and compliance with the Machine Directive 2006/42/EMC as well as other relevant safety and quality standards, the motors and components are designed for easy operation, long life cycles and minimal maintenance.

“Apart from the Smart Reset roll-up door’s rugged construction, the feature which positions Apex Strip Curtains & Doors as a market innovator is the door’s self-repairing capabilities. Should the curtain be accidentally dislodged, it quickly recovers its alignment on its next opening or closing operation,” Dessing points out.

This is made possible by the incorporation of side hinges that slide along special guides, together with the flexible curtain ends that protect the door from damage. On impact with an obstruction, the hinges dislodge themselves to prevent tearing or harm to personnel and goods.

The action is further driven by a DSC electronic safety device that automatically reverses the motion of the door should it hit an obstacle when closing. This IEC-compliant device can be activated by any type of remote control equipment including photocells, pressure sensitive mats, movement detectors and induction loops.

“In addition, a manual release lever allows one to open the door from either side should a power failure or malfunction occur,” Dessing explains.

The Smart Reset roll-up door is supplied with a three phase 400 V externally mounted motor that includes a limit switch and electrically operated hand brake. Suitable for openings of up to 2 metres high and 4 metres wide, the doors are manufactured in Class 2 self-extinguishing polyester which has demonstrated its ability to withstand winds of up to 120 km/h.

Robustness and longevity were defined as important features, so the doors include a soft start and soft stop capability to reduce mechanical stress and wear. An optional inverter system is available when easy speed adjustments are a prerequisite. The precise and uniform rolling of the curtain is ensured by the combination of the two photocells that are mounted inside the casing of the door together with the DSC electronic system.

Aesthetically unobtrusive and compact, the Smart Reset roll-up doors are not only easy to install and operate but also provide companies with the assurance of unobstructed and safe access for vehicles and personnel. “These doors have provided a cost effective solution to the large roll-up door dilemma of ensuring speed of opening and closing, while at the same time ensuring that both people and goods are protected,” Dessing concludes.

ENVIRONMENTAL PROTECTION A BONUS WITH IPR’S SLURRYSUCKER®

The need to incorporate environmental preservation techniques on site has become an ongoing and critical action point for the global mining and industrial sectors. Ensuring water contaminated spaces do not negatively affect surrounding areas is one such area where slurry and dewatering pump specialist Integrated Pump Rental can assist through its SlurrySucker® slurry removal solution.

Not only does Integrated Pump Rentals’ SlurrySucker® dredging system effectively clean process water ponds, return water dams or other water storage areas, it has become recognised as an ideal solution for cleaning water capture areas where silt or slimes is an issue or where water retention and water holding capacity is being threatened. Some of these areas are environmentally sensitive and must be protected from causing any pollution.

“Through our SlurrySucker® product range, we are now able to offer a complete solution to effectively remove slurry from any water-based environment and in so doing now offer one of the most cost effective solutions for any dam cleaning project,” says Lee Vine, managing director for Integrated Pump Rental.

The benefits of the SlurrySucker® extend well beyond improving mines’ environmental footprints. They enable increased water storage, the recovery of minerals and improved processing water quality.

“They further make it significantly easier to extend the life of water-dedicated assets by for example protecting dam plastic liners. Clients are consequently able to incorporate slurry removal projects into their planning in order to extract greater value from all non-mining areas,” Vine outlines.

The SlurrySucker® dredge system incorporates world renowned Grindex slurry pumps, making it the most efficient and cost effective electrically powered floating dredge system designed on the market.

Bodies of water, such as ponds, lagoons, dams and canals should be considered valuable plant assets and must be maintained to maximise their operational efficiency and contribution to optimised operational performance and the SlurrySucker® will deliver in this area without fail,” Vine confirms.

The SlurrySucker® is sized to meet the clients’ slurry removal requirements in terms of particle size, aggregation, distribution, cohesiveness, flow characteristics, sedimentation rates and specific gravity. Typical suction water agitation dredging usually achieves 20% – 30% solids for SGs up to 3.0.

Vine highlights two product options – the Maxi SlurrySucker® which is capable of moving 250 m³ an hour at 20% – 30% by volume – equivalent of approximately 70 dry tons per hour. The Mini SlurrySucker® operates at 100 m³ an hour, again at 20% – 30% by volume for roughly 30 dry tons every hour.

Whether it is short-term pond clean-ups or ongoing pond management projects, the SlurrySucker® is designed for difficult site conditions for many applications including:

• Mining – Process ponds, pits, tailings storage
• Energy – Power stations, oil refineries
• Industry – Chemical storage ponds
• Storm water – Sedimentation dams

“We believe the SlurrySucker® is the easiest method of dredging thanks to remote controlled height adjustment of the primary slurry pump and dredge head assembly,” says Vine.

The SlurrySucker® comes standard with galvanised frame structure and Integrated Pump Rental’s flexible design provides the optionality for stainless steel with polyethylene and UV-stabilised pontoons.

NEW CONCOR HEAD URGES QUICKER PACE TO CONSTRUCTION RECOVERY

Concor’s new group CEO Lucas Tseki is confident South Africa’s construction sector is turning the corner, provided there is no further delay in the adjudication and awarding of large infrastructure contracts by government agencies.

“Concor has weathered one of the industry’s worst downturns and emerged with a robust balance sheet to capitalise on our current and future opportunities,” says Tseki. He says government needs to send the right message by speedily awarding contracts and putting contractors to work.

“As Concor, we are battle-hardened by the past few years and ready to embrace the prospects of 2020 and beyond,” he says. “For my part, I am ready to listen, to learn and to lead.”

The black-owned infrastructure and building construction company, previously Murray & Roberts Construction, is leveraging over a century of experience to become the leading player in its segment.

Tseki acknowledges there are many challenges lying ahead for the construction sector. Not least of these is the rebuilding of trust between key stakeholders including contractors, government, banks, developers and labour.

“The pressures of a low growth economy have strained relationships between the players in the industry,” he says. “We must now generate a more collaborative approach that prioritises continuity and sustainability in how we deliver and maintain the nation’s infrastructure.”

He emphasises that South Africa’s future economic growth relies on sound and ongoing investment in quality construction projects. Given the poor state of the economy, it is likely that innovative funding and contractual solutions will be required to pursue the necessary infrastructural and industrial developments.

“Effective Public-Private-Partnerships (PPPs), for instance, are becoming more vital,” Tseki says. “These could advance infrastructure development in education, healthcare, water, transport and other areas, especially where state expenditure cannot keep up.”

He says Concor’s solid track record in project delivery, commercial management and safety performance equips it to manage complex projects of this kind. He notes that there is appetite among lenders for innovative project models that are based on sovereign risk, while contributing to national developmental priorities that will fuel broader growth.

“As a company, Concor’s world-class heritage and proven ability to execute on time and within budget makes us a valuable partner,” he says. “The country needs the confidence to move into PPPs, but there is no time to lose.”

Concor is active in both inland and coastal projects, and has a strong presence in SADC. It has also just been awarded a large ash disposal facility contract at Eskom’s Majuba Power Station.

IMPROVED LOCAL DESIGN OF ENDURON VIBRATING SCREENS BY WEIR MINERALS

With its extensive range of Enduron® vibrating screens proven over the past 40 years, Weir Minerals Africa is now locally designing and manufacturing new-generation linear motion vibrating screens.

According to Christian Stehle, head of engineering at Weir Minerals Africa, this design capability provides the flexibility to produce vibrating screens to suit each customer’s plant layout. At the same time, the designs will optimise cost, efficiency and performance. South Africa also hosts Weir Minerals’ global screening and separation technology group.

“This expertise ensures that our robust Enduron vibrating screens provide exceptional classification and dewatering screening performance,” says Stehle. The screens are deployed in a wide range of minerals processing applications. He notes that vibrating equipment is generally more challenging to design than static equipment due to the high-frequency cyclic loading to which the machines are subjected.

“The final design must address key criteria like screening efficiency, throughput and loading, while still operating within the acceptable fatigue life limits of the materials of construction,” he says.

Stehle highlights that the use of Finite Element Analysis (FEA) tools allow engineers to optimise screen life by obtaining the stress and deflection levels in the equipment and applying the appropriate structural design and utilisation of materials in the areas experiencing high stresses.

“Traditionally, screen designs used to be heavier in an effort to extend the life of the equipment,” he says. “Using FEA tools during the design stage allows us to retain structural integrity while actually reducing the overall weight of the machine.”

While there are areas of high stress on the equipment that need more strength, technology tools indicate where lower stresses occur. In these areas, less steel can be used to make the structure lighter. Leveraging this technology, the weight of some new-generation screens has been cut by up to 15%.

One of the new, modern screen designs is part of a recent Weir Minerals Africa complete comminution plant contract for a South African mining project. The scope includes two crushing stations, a screening station and all the related feed chutes, bins and conveyors.

Stehle notes that Weir’s Synertrex™ IoT platform can also be applied to monitor and improve the performance of its vibrating screens. Synertrex™ technology is an industrial internet of things (IIOT) system that allows operators to monitor every aspect of their equipment’s operation, to prevent problems and increase throughput.