TURBINE DRIVE TRAIN OVERHAULED IN JUST SIX WEEKS

In a recent major overhaul of a 70 MVA turbine generator set, Marthinusen & Coutts, a division of ACTOM (Pty) Ltd, contracted with South 32’s Metalloys to take full responsibility for entire drive train refurbishment.

Working in collaboration with business unit ACTOM Turbo Machines, Marthinusen & Coutts completed the work successfully within six weeks. The electrical generation plant is at Metalloys’ manganese plant in Meyerton, Gauteng.

According to Mike Chamberlain, Marthinusen & Coutts’ marketing executive, this achievement showcased the capacity of the divisions to take full control of large mechanical and electrical refurbishments. Chamberlain highlights that the customer did not want to split the responsibility for the complete generator and turbine drive train between separate contractors.

“Marthinusen & Coutts and ACTOM Turbo Machines’ capabilities enable us to control the entire process, offering peace of mind to customers, coupled with optimised cost efficiencies,” says Chamberlain. “This also reduces customers’ risk and managerial effort in dealing with multiple suppliers.”

The scope included a complete inspection of the turbine rotor and internal components, as well as runout and dimensional inspection on the rotor. Inspections incorporated glass bead blasting and non-destructive testing of many components.

High-speed balancing of the 13 tonne rotor was conducted, and turbine rotor journals were repaired. White metal bearings were relined, and the thrust bearing was modified to improve fitment in the bearing casing. Positive material identification tests were conducted on all the studs, nuts and shaft seals. A complete 3D scan was done of the centreline to allow reverse engineering drawings.

At is repair facility in Cleveland, Johannesburg, Marthinusen & Coutts also performed a number of inspections, tests and repairs on the rotor. Dimensional inspections and electrical tests were conducted, as well as non-destructive testing such as the phase array test. Slip rings were ground, the diode wheel was inspected, and the diodes were tested.

ACTOM Turbo Machines inspected and refurbished the auxiliary mechanical equipment. This included lubrication and control oil systems, pumps, coolers, and white metal bearings on ID and FD fans. ACTOM Turbo Machines project manager Hannes de Jager notes that an overhaul of this magnitude and scope would usually take over two months.

“The excellent working relationship we had with Metalloys’ technical staff, and the cooperation we got from them certainly contributed to completing the work as quickly as we did,” says De Jager. Starting the inspections, tests and repairs in July, the team completed the overhaul by mid-August.

Representative SAMPLING – KEY TO SUCCESS IN AFRICA’S COMMODITIES

The growth and diversification of West Africa’s mining sector is making the precision of mineral sampling a vital priority.

“West Africa is a growing market for Multotec samplers and services, with the increased output of commodities adding a new dimension to the importance of our equipment,” says Willem Slabbert, process manager at Multotec Process Equipment.

For over two decades, Multotec has been active in the West African market, with its proven samplers at over 30 sites in countries including Ghana, Liberia, Burkina Faso, Guinea, Sierra Leone, Mali and Guinea-Bissau. A range of commodity sectors use the equipment for both slurry and dry sampling applications, among them gold, bauxite, iron ore and heavy minerals.

Multotec has also presented representative sampling training courses explaining the practical aspects of implementing the Theory of Sampling (TOS).

“In bulk minerals like bauxite – where our sampling plants have been in operation with a major West African producer for 17 years – the sampling protocol and “correctness” of equipment design is key to ensuring bottom-line success,” says Slabbert.

He highlights the importance of reproducible and accurate sampling – cumulatively termed representative – at the interface between the mine and port, and on the ship-loading conveyor to the client.

The sampling, which must comply with ISO standards and best practice as prescribed by the Theory of Sampling (TOS), confirms the mine is supplying product to the end-customer’s contractual specification. “Any imperfection in the sampling process can lead to unnecessary contractual disputes and potential financial losses for the mine or client,” he says.

Multotec supplies wet slurry samplers to many gold mines in West Africa, who rely on good gold accounting and reconciliation at their processing plants. The equipment is popular among large gold producers as well as the smaller entrants.

“With a comprehensive range of Two-In-One, primary and ancillary samplers, we are able to tailor each installation to the customer’s specific application,” he says. “This means accommodating variables like throughput rates and slurry densities, including accounting for grade variability from various mine sources feeding a single processing plant, in many of the West African deposits.”

For brownfield projects, Multotec can design solutions to suit and fit the structural constraints of the customer’s existing infrastructure.

Local service support is available from Multotec’s Ghana branch as well as regional agents and service providers operating in other countries. This ensures a point of contact as first line of support and drawing on its expertise across a range of disciplines, Multotec can put specialists, engineers, design draughtsmen and millwrights to work on projects throughout the West African territories. This ensures optimal placement and performance of equipment to safeguard customers’ profitability.

AFRISAM ENCOURAGING APPROPRIATE BEHAVIOUR OF CEMENT CONSUMERS

With South Africa’s carbon tax in force from 1 June this year, AfriSam is providing customers with transparent pricing and the ability to make greener choices.

According to Richard Tomes, sales and marketing executive at AfriSam, the way the company complies with the new carbon tax is aimed at encouraging the appropriate behaviour of consumers. Rather than apply a blanket price increase, AfriSam is allocating the amount of carbon tax due on each bag of cement.

The carbon tax is a levy that varies according to the amount of carbon emitted in the manufacture of a product. The different cement brands in AfriSam’s range contain varying amounts of clinker – the most energy-consuming element of cement. This means that the carbon footprints of the brands differ from each other.

“We are taking a transparent and responsible approach to the new tax,” says Tomes. “By showing the amount of carbon tax payable on each specific bag of cement, our customers will still see the base price that we are charging. This avoids any confusion about how much of the final price is going toward the tax.”

He notes that this approach will also make it easier for customers to identify the AfriSam cement brands with lower carbon footprints.

“We believe that a tax should not just be a punitive tool, but it should also affect behaviour in society,” he says. “Just as cement producers are working hard to reduce carbon emissions, so the end-user can also play their part by choosing an environmentally-friendly brand.”

While certain specialist cements demand higher clinker content, he says AfriSam increasingly uses extenders to create high-quality cement brands with lower environmental impact.

EVEN CLEANER COAL WITH MULTOTEC’S NEW SX10 SPIRAL

Multotec Gravity Division has taken ‘low cut’ spiral technology to the next level with its new SX10 low density spiral. This further extends the benefits this innovation offers in fine coal beneficiation.

According to Multotec technology manager Faan Bornman, the Multotec SX10 low density spiral’s reduced cut point of 1,55 g/cm3 delivers considerable advantages over the cut points of between 1,6 and 1,8 g/cm3 typically achieved in the industry today.

The result, he says, is a cleaner coal with less waste being achieved in a single stage. This saves on capital costs as no further spiral stages are required for cleaning down the line. The approach taken with the Multotec SX10 spiral is to remove the gangue, or mineral containing particles, from the trough in two off-takes.

The first off-take removes ash. This opens up the available separation surface of the spiral, allowing the remaining material to separate more easily, separating clean coal from less-clean coal.

“The low density spiral is essentially a primary and secondary stage on one centre column,” Bornman says. “Rejects are discarded into the centre column and the remaining product is repulped before being sent to a secondary off-take.”

Facilitating the two off-takes is a longer spiral on the Multotec SX10. This increases the residence time and gives the particles sufficient time to separate.

Depending on the setting of the product box splitters, this new spiral has the ability to produce a thermal coal and a coking coal on one spiral. Bornman says this was proven through test work done in the USA. The two offtakes enable the removal of most of the gangue leaving a middlings and cleaner coal products to be collected at the dart splitters.

Experimental work was carried out using coal from two South African collieries as well as doing site test work in the USA. Promising results were obtained leading to the first order for Multotec SX10 spirals from a North America-based mine.

SUCCESSFUL CONSTRUCTION OF CRESTAQUARIUM BY CONCOR BUILDINGS

The indoor CrestAquarium at Cresta Shopping Centre allows shoppers to view more than 30 species of fish. Constructed by Concor Buildings and unveiled to the public in June 2019, this ‘edu-tainment’ feature is on the lower level of the centre’s food, entertainment and cinema court.

Specialist Italian experts provided the pure cast acrylic blocks for underwater use, and Martin Muller, contracts manager at Concor Buildings explains that one of the first challenges during the project was the logistics of getting these large acrylic panels into place.

“The panels were shipped in two pieces, each measuring five metres in diameter and four metres high,” Muller says. “With each item weighing about four tonnes, they were transported in jigs and trolleyed into the confined space of the shopping centre.”

To create enough space to access the lower level, one of the shopping centres escalators was removed completely to facilitate access for the trolleys. A spider crane, positioned on the food court level above, was used to lift and position each panel. The weight exerted by the crane’s activities was considered during this operation, with back propping of the slab on which it rested being done.

Various other technicalities related to the CrestaAquarium’s operation were also attended to by Concor Buildings. This included two pump rooms and acclimatisation baths for the fish which were used before they were introduced to their new home.

“After establishing the cast concrete base for the CrestAquarium structure, we also installed service ducts for water reticulation,” Muller says. “Another important aspect was the pressurised extraction system used to prevent dust ingress.”

Concor Buildings also built insulated panels around the acrylic structure, which ensured the required heat levels allowing the panels to bond and cure over a number of weeks.

“The next phase was quite technical, with the top of the CrestAquarium being covered with a fibre-reinforced plastic cap, including stainless steel components to avoid corrosion,” says Muller. “An added consideration in almost all our work on this project was that we were working in a live environment. The centre was busy with shoppers and visitors, so it was important as always that we worked with safety as a priority.”

The final aspects of the project included the placing of custom-made, marine themed mosaics in the floor around the CrestAquarium, and hydro-testing of water pressures and equipment. Concor Buildings started on the project in August 2018 and completed it in May 2019.

SOUTH AFRICA SEES VALUE FROM FLSMIDTH’S NEXTSTEP INNOVATION

FLSmidth’s innovative nextSTEP™ flotation technology is proving itself in the South African mineral processing space.

According to Ricus van Reenen, Regional Product Line Manager – Separation at FLSmidth, the nextSTEP™ rotor and stator combination has been at work for over a year at a large South African platinum mine, achieving positive results.

“The customer has achieved significantly lower power consumption on the full-scale retrofits we installed early in 2018,” says van Reenen. “The more efficient design allows the same or higher slurry circulation at reduced rotor speed, leading to lower power draw.”

The retrofits have been applied to both primary and secondary flotation applications, where energy savings of over 10% have been achieved. Years of research and development have been invested in the nextSTEP™ technology, which was originally launched in 2015.

Among the key design elements are the addition of slots to the stator, adjustments in the rotor profile and a parallel distance between the rotor and stator.

“Energy dissipation is now more uniform than in traditional forced-air designs,” van Reenen says. “This means a more even wear pattern across the rotor and stator, and therefore longer intervals between maintenance.”

In the South African installations, the wear on the rotors and stators has been minimal after more than a year’s operation. In the one flotation cell, the equipment has been operational for 15 months. The thickness of the rotor has reduced from 65 mm to only 60 mm, and the stator from 75 mm to 70 mm. After 13 months of operation in the second installation, the wear is even less. The rotor’s thickness has reduced from 65 mm to 63 mm, while the stator was down from 75 mm to 73 mm.

Van Reenen highlights that there have been other benefits experienced by local users of the new technology. Among these has been 16 to 18% less blower air usage, with more concentrated bubble formation.

“Better turbulence energy dissipation around the rotor and stator region, with its related finer bubble size distribution, creates more surface area for bubble-particle attachment,” says van Reenen. “This has delivered more froth and a higher mass pull on our local units.”

The success of the nextSTEP™ technology has led to further retrofits being planned in South Africa, which is in line with FLSmidth’s drive to promote mines’ productivity and performance. Van Reenen says the intensive R&D process continues apace and is not just in the rotor and stator design but also includes areas such as smart control systems and continued digitalisation of process solutions.

QUALITY STRIP CURTAINS OFFER AFFORDABLE SOLUTION

High quality PVC strip curtains offer an affordable solution in applications where dirt, dust or insects need to be kept out and where hygiene, humidity, temperature and noise need to be controlled.

Apex General Purpose Strip Curtains offer another advantage apart from high quality manufacture, and this feature ensures longer life even under harsh operating conditions according to Wim Dessing, sales executive of Apex Strip Curtains & Doors.

Locally manufactured under stringent quality control conditions, Apex General Purpose Strip Curtains feature the patented Balledge® design which facilitates an optimal thermal seal. The specially reinforced edges on individual strips allows these to part easily under pressure allowing people and goods to move through unhindered. The rounded edge also ensures the strips do not snag or scratch goods or people as they move from one area to another.

Made from specially formulated PVC material which is transparent allowing good visibility between cordoned off areas, the Apex General Purpose Strip Curtains are equally at home in heavy engineering and light fabrication facilities as well as packaging and warehouse operations.

Dessing cites as an example instances where the product has been used to enclose loud machinery to contain noise levels or where it is used to control levels of humidity where this is critical to the quality of finished products.

“Tests have shown that PVC strip curtains can reduce noise levels by between seven and fifteen decibels, and this certainly assists in improving working conditions,” he says.

In packaging and warehousing operations where keeping the temperature at specific optimum levels is critical, use of strip curtains has proved invaluable. Applications where temperature control is important also include food preparation areas, cold storage and freezer areas, as well as refrigerated trucks. In such facilities, PVC strip curtains are also effective in keeping out dust and insects thereby maintaining high levels of hygiene.

Similarly, in pharmaceutical and chemical plants PVC strip curtains are used to ensure hygienic and dust-free manufacturing and packaging areas.

Apex Strip Curtains & Doors has been manufacturing PVC strip curtains since 1981, and the company’s team is able to assess individual applications and propose the best fit solution to meet the operating parameters.

SAFE, RAPID DEMOLITION OF RUSTENBURG PELLETISING PLANT

A turnkey demolition contract is underway at a chrome pelletising plant in Rustenburg, after being secured by Forte Demolition Solutions.

A subsidiary of surface materials handling expert SPH Kundalila, Forte Demolition Solutions is tackling the project with its specialised range of mechanical dismantling and demolition equipment.

“Our investment in this equipment is substantial, making us the ideal partner for mines and other operations who need to address closure in a safe and sustainable manner,” says Graeme Campbell, group commercial operations manager at SPH Kundalila.

The plant to be demolished includes several multi-storey structures, conveyors, steel frames and concrete work, as well as large, heavy componentry. Campbell emphasises that Forte Demolition is one of few companies in South Africa with the necessary assortment of fit-for-purpose machinery and attachments. These ensure that the cutting and breaking process is safe and efficient. It also allows many components to be carefully dismantled for resale purposes.

“Among the factors behind our cost effectiveness is that we can shorten customers’ timeframes,” he says. “For example, our precision cutting is done by a shear attachment on an excavator. The power of hydraulics – combined with our specialised technology – means that everything is much quicker and safer.”

Equipment that is being employed on the pelletiser site includes a pulveriser for concrete demolition. It breaks concrete into small pieces that can be used as backfill on site, obviating the need for transporting large concrete chunks to special dumping sites. Other specialised demolition attachments that make Forte Demolition Solutions’ work both productive and safe are grapples, hammers and buckets.

High levels of safety are ensured by an integrated safety, health, environment and quality (SHEQ) management system, according to Brad van Niekerk, project manager at Forte Demolition Solutions.

“Safety is our key priority, which is enhanced by the closely supervised use of our mechanical equipment,” says van Niekerk. “This ensures that workers are not placed at risk by being too close to dangerous working environments.”

He notes that each project is planned and monitored by a skilled professional team, which takes the safest demolition approach. This is also aligned with customer standards to ensure full compliance with corporate and regulatory requirements. The company is also experienced in asbestos removal.

“With our own dedicated asbestos decontamination units and decontamination equipment, we can safely conduct demolition and disposal of asbestos cement, wall cladding, pipes, gutters and other fixtures,” he says. “We work closely with a registered hazardous waste removal specialist to ensure full regulatory compliance.”

A 51% black-owned business and Level 2 B-BBEE contributor, Forte Demolition Solutions operates nationally through its offices in Fochville, Rustenburg, Stilfontein and Carletonville.

HYDRAULICALLY DRIVEN DEWATERING PUMPS ADDED TO INTEGRATED PUMP RENTAL FLEET

No two pump rental applications are unlike, and it is this understanding that has positioned Integrated Pump Rental as one of the leading pump rental operations in South Africa.

Managing director, Lee Vine, says that some dewatering applications are simple plug-and-play operations where access to electric power is not an issue, but others, especially in remote or difficult to reach areas, require the use of diesel driven pump sets. “Large diesel driven pump sets are not always the answer where electricity is not available and to provide customers with a effective solution we recently introduced the Quax hydraulically driven pump range into our fleet.”

Not only will these hydraulically driven submersible pumps complement the existing Integrated Pump Rental fleet by filling the gap between the electrically operated submersibles and those powered by diesel, it will also open opportunities for the company to extend its reach into other markets. Vine says these include dewatering on construction and infrastructure projects in built-up areas as well as in the wastewater treatment sector.

“Quax is well proven in Europe. It is a reliable workhorse that can pump in all sorts of conditions. Apart from dealing with large particles and sludge, the pumps work particularly well where suction lift can be an issue,” Vine says.

The Quax range of submersible pumps includes a 2”, 3”, 4” and 6” unit, and all units are equipped with a run-dry capability which is considered essential in dewatering applications. The pumps are simple to install and operate, and offer reliable pumping even under challenging conditions. This, Vine, says enables end-users to dewater effectively in areas that are traditionally difficult to reach.

The pumps are equipped with a range of impeller option, increasing the versatility of these units. This includes a two bladed impeller for dealing with large particles, a screw impeller for pumping in thick sludge, a stainless steel impeller for applications with a low pH and a high head impeller.

Each hydraulic powerpack is well suited to the individual pump making it compact yet powerful, and each has an automatic shutdown feature should the installation operate outside of its set temperature parameters. The silent powerpack is fully enclosed which reduces noise during operation and makes these units suitable for operation in suburban area.

All pumps are supplied with the requisite accessories for the dewatering application at hand, and this includes pump hose flotation devices.

Quax hydraulically driven submersible pump are available from Integrated Pump Rental for outright purchase or for rental.

REGULATING EFFICIENCY IN MOTORS CAN HELP STABLILISE SOUTH AFRICA’S POWER SUPPLY

South Africa could go a long way to cut the risk of future load-shedding by adopting a minimum efficiency performance standard (MEPS) for electric motors.

According to Fanie Steyn, manager rotating machines at Zest WEG Group, a MEPS would significantly reduce the peak power demand on the national grid. Importantly, the step could be made at no cost to government and would also bring substantial savings to industry’s electrical energy costs.

“The MEPS would phase out the least-efficient electric motor classes by setting a minimum standard for the efficiency of motors imported and sold in South Africa,” he says. “The essential challenge now is that about 280,000 electric motors are imported each year, many of which are low efficiency motors rated at IE1 level as standard.”

Steyn highlights the great strides recently achieved in the efficiency of electric motors. Energy savings of between 2,1% and 12,4%, depending on the individual power rating, can be made by converting from a standard efficiency IE1 motor to a premium efficiency IE3 motor. The capital cost differential is slight and is quickly recouped by lower operating costs.

“It is estimated that as much as 30% of all energy produced globally is consumed by electric motors,” he says. “It is therefore easy to see why improving motor efficiencies has a huge impact on national energy consumption.”

It is significant that more than 42 countries already have MEPS in place. These standards apply mostly to three-phase low voltage motors from 0,75 kW to 375 kW capacity. The MEPS is applied at import stage, so the process would be handled in the conventional manner by customs agencies.

“If the 150,000 low voltage motors entering the country each year were IE3 rated instead of IE1, the national grid could be relieved of about 195 million kWh in a single year,” says Steyn. “This means almost three billion kWh over the next five years.”

He adds that this would also mean lower carbon emissions from power stations. South Africa has committed to reduce these emissions by signing the Paris Agreement in 2016.

“Implementing MEPS will have significant benefits for everyone,” Steyn concludes.

The Zest WEG Group, a subsidiary of leading Brazilian motor and controls manufacturer WEG, has a strong commitment to contributing to the development of the African region, and has been servicing the continent for more than 37 years.