REGULAR DESILTING VITAL FOR MINE PONDS

Ensuring sufficient water storage capacity in mines’ process ponds is crucial for the optimal functioning of mineral treatment plants, and this means regular desilting must be conducted.

This is according to Lee Vine, managing director of Integrated Pump Rental, whose company is frequently called upon to urgently attend to process ponds that have silted up. 

“While too much silt in these ponds can disrupt plant operations, this situation also raises the risk of over-topping which can lead to costly environmental damage,” says Vine. “Our locally developed SlurrySucker system can readily address the problem, but it should not be left too long. Ideally, mines would have a pond monitoring strategy and a regular schedule for desilting operations.”

He highlights that fully functional process ponds are increasingly important elements of a mine’s water balance, as mines actively pursue water conservation efforts to make themselves more self-sufficient. Strategies include more reuse of mine water, so ever-closer management of water flows is necessary.

It is usually possible to observe the bank of silt building up once it fills about 40% of a pond’s volume, he says. This indicates that prompt action is required. 

“With our proven technology, the desilting is relatively straightforward and not labour-intensive. It can be conducted effectively by just a couple of operators with the required training,” he says. He notes that recovering the value of the minerals in the silt can often cover the cost of desilting, with many mines being designed to recycle the sediment back into their process plants.

Choosing whether to contract-out the desilting function or conduct it in-house will depend on each mine’s conditions and preferences, says Vine. Integrated Pump Rental can provide the desilting service on a turnkey contract basis or rent the necessary equipment to the mine. For some mines, it might make sense to invest in their own SlurrySucker unit.

“We work with customers to find the right solution, assessing their detailed requirements before making a proposal,” Vine says. “Where mines wish to conduct the work themselves, we can train their staff and fully support the equipment with prompt parts availability and all the necessary engineering and maintenance services.”

FIRM LOCAL BASE SETS UP ZEST WEG FOR AFRICA GROWTH

Establishing a strong local manufacturing base in South Africa has been integral to Zest WEG’s success over the past decade, building the economy and providing an important springboard into Africa.

This process has aligned closely with the strategic approach of Brazil-based parent organisation WEG, which prioritises its member companies’ capability, efficiency and innovation on a local level, according to Juliano Vargas, CEO of Zest WEG.

“This has required considerable investment in our local production capacity and skills base,” says Vargas. “The outcome to date has been very successful, with Zest WEG developing its local structure and supply chain , while working to world class standards and supported by WEG innovation.”

As an example, he notes that Zest WEG today achieves almost 90% local content capability for its transformers and more than 70% local content capability for other products such as E-houses and panels. These products form part of the company’s wide range of solutions, including electric motors, drives, switchgear, energy generation, electrical infrastructure, and generator sets, with different levels of localisation.

This locally developed supply chain delivers various benefits to customers, says Vargas. These include short lead times, as there is little reliance on Europe, China or the US for parts and components. 

“The impacts to our market are considerable, and we have more predictability and control of our supply chain,” he says. The company has embraced South Africa’s commitment to transformation, achieving Level 1 B-BBEE status and investing heavily in training and enterprise development. 

It helped that WEG is a member of the BRICS Business Council (representing Brazil), so it has over the years been able to engage with South African authorities about local content requirements and industry development opportunities.

“Our business – both in Brazil and South Africa – has put our weight behind economic empowerment and transformation, focusing heavily on local suppliers and local skills,” he says. 

Zest WEG’s investment in human capital exceeds the portion of payroll demanded by B-BBEE in local training. Among other initiatives is a bursary programme, and it will shortly employ its third electrical engineer from this scheme. 

Vargas highlights the powerful launchpad that this groundwork has created for growing the company’s footprint in Africa, where it also applies its local development philosophy by partnering with in-country Value Added Resellers (VARs). 

GLOBAL INNOVATION AWARD FOR SANDVIK

Simon Andrews, managing director at Sandvik Mining and Rock Solutions, is thrilled to announce that Sandvik AutoMine® and OptiMine® have been recognised by the 2020 Global Autonomous Mining Solutions Product Leadership Award by Frost & Sullivan.

Frost & Sullivan Best Practices Awards recognise companies in a variety of regional and global markets for demonstrating outstanding achievement and superior performance in areas such as leadership, technological innovation, customer service and strategic product development.

”Sandvik is the only mining equipment and solutions company that was awarded in our 2020 Class of Top 50 Digital Best-practitioners across the Industrial and Energy Space,” says Rohit Karthikeyan, Industry Analyst at Frost & Sullivan.

The AutoMine® system is an innovative automation solution that comprises AutoMine® Underground and AutoMine® Surface Drilling, enabling customers to scale up the mining automation at their own pace. 

The AutoMine® Underground product family includes the sub-products AutoMine® Tele-Remote, AutoMine® Lite, AutoMine® Multi-Lite, and AutoMine® Fleet. AutoMine® Surface Drilling is an automation solution available for a wide range of Sandvik’s iSeries top hammer, down-the-hole and rotary drills.

“One of the biggest competitive differentiating factors is that Sandvik is a mining equipment/mining process and digital solutions provider,” says Karthikeyan. “This expertise in technical, industrial and digital domains enables it to deliver compelling offerings that outperform peers’ products to the market.”

Riku Pulli, President, Rock Drills and Technologies Division, Sandvik Mining and Rock Solutions, says: “We are continuously developing innovative technologies that benefit our customers’ operations and this award indicates the success that Sandvik has achieved with our automation offering over the years.”

EVOLUTION OF CYCLONES TO IMPROVE COAL FINES RECOVERY

Continuous improvement of Multotec classification cyclones helps customers meet both commercial and environmental imperatives in the coal sector, according to Ernst Bekker, product specialist cyclones at Multotec. 

“Today, there is an intense focus on the beneficiation of coal fines, which in the past were generally discarded,” says Bekker. “There is greater awareness of the environmental impact, and it also makes good economic sense to recover more.”

He highlights, however, that dewatering of fines can be costly. Multotec’s efforts to make the process more cost effective have included the investigation of alternative inlet designs, which achieve more efficient separation, especially with fine coal. Also, important has been the incorporation of alternative wear materials, to extend the life span of these cyclones.

“Our focus is on the mechanical life of our units and their physical ability to last, but we also want to extend their efficiency life cycle, so that they perform well for longer,” he says. Ongoing wear creates undulations on the inner surface of a cyclone, for instance, and this causes inefficiencies. 

“Ceramic tiles might last longer, but other materials might retain a smoother surface for better separation,” he says. “Using these alternative materials, we can design custom solutions to suit the application; this ensures the customer is always getting optimal value throughout our cyclones’ entire lifespan.”

He also notes that the company’s overall sensor development programme is giving attention to monitoring wear lining thickness and performance conditions in classification cyclones. 

“With sensor technology, we will be able to pick up roping conditions in the spigot, for example,” he says. “We believe there is even scope with these units to leverage artificial intelligence to help us achieve optimal operating conditions.”

SOLID FOUNDATION FOR DE WATERKANT HERITAGE PROJECT

Variable ground conditions at an upmarket mixed-use development in Cape Town has demanded some innovative solutions from contractor GVK-Siya Zama Construction and readymix specialist AfriSam.

At the Old Cape Quarter project in De Waterkant, four floors of luxury apartments are being added to retail and office space. This meant substantial strengthening of the foundations and columns to accommodate the increased load, according to Garth Robb, contracts director at GVK-Siya Zama Construction. This was not a straightforward process, says Robb, with insufficient space in the basement areas for normal class 3 formwork. 

“We made extensive use of biscuit columns, where we added reinforcing around the old existing columns and core-drilled at an angle from above – adding grout to beef up the column sizes,” he says. “We core-drilled through the base to transfer the load onto the piling, with a number of columns and bases needing to be demolished and reconstructed.”

A key complication was that concrete could only be poured manually into the biscuit columns by wheelbarrow, through 60mm core holes from the slab above. Each column took up to an hour to pour, with admixtures accelerating the hardening rate of this highly fluid 60MPa concrete. 

“There was no option but for concrete to be delivered in smaller volumes, otherwise the concrete would harden in the trucks before it could be used,” he says. “AfriSam worked closely with us to find a solution, which was to deliver just one cubic metre of readymix at a time.”

Readymix trucks usually carry six to eight cubic metres, so carrying just a fraction of this had severe implications for efficiency. However, the situation demanded flexibility from both partners, says AfriSam territory manager Melanie Ross, and the needs of the customer had to come first. 

“Also, the pours could only start in the afternoon, and often continued beyond the 18h00 deadline agreed between the contractor and the authorities,” says Ross. “So extended permissions were obtained, and the AfriSam-contracted drivers agreed to put in the extra time until pours were completed.”

AfriSam supplied over 9,700 m3 of readymix to the Old Cape Quarter project, and about 10 different concrete mixes for different applications. These came from the company’s Woodstock plant about 8km from site and its Peninsula Quarry plant at Durbanville.

GETTING THE RIGHT TOOLS FOR MINING TO GO DIGITAL

The astute application of digital tools is the key to continuously improving efficiencies on underground mines, according to Niel McCoy, business line manager for automation and digitalisation at Sandvik Mining and Rock Solutions.

McCoy says that the choice of digital tools needs to be based on each operation’s key performance indicators (KPIs). This is because the solutions that are implemented will be focused on monitoring and managing those KPIs. He then recommends a phased approach to introducing digital tools to an operation. 

“The starting point is always machine telemetry and basic production or productivity reporting,” he says. “From there, the solutions can be expanded.”

Sandvik Mining and Rock Solutions has extensive global experience in designing and implementing digital tools, including equipment health monitoring and process management. Its AutoMine® automation offering operates on 59 mining sites globally, while its OptiMine® suite of digital solutions is active on 66 connected sites. The ‘My Sandvik’ customer portal, a web-based digital hub, serves 214 sites and its Newtrax technology in wireless IoT connectivity is operating on 115 sites.

“Monitoring equipment health through My Sandvik Digital Services Solutions allows users to draw down telemetry data from their equipment in real time,” he says. “The data is automatically compiled into the required report format for quick analysis and response.”

The next aspect to be addressed is the actual management of the process being monitored, he says. This is where Sandvik’s Task Management and Scheduler – part of its Optimine® suite of digital solutions – can be applied. 

“This allows a tablet to be fitted to an item of equipment so that an underground operator can accept tasks and provide real-time progress reports on those tasks,” he says. “The more advanced the equipment, the more data can be extracted and communicated automatically without operator intervention.”

The solutions allow for data to be recorded on equipment’s key operations – such as the weight of loads in a loader bucket. Telemetry on the equipment gives valuable insights into the equipment’s availability and performance – so that management can respond. 

“When starting digital journeys, the focus must be on improving current operations,” says McCoy. “This means getting work started on time, for instance, before moving onto optimisation efforts. Most digital implementations will battle if the starting point is trying to increase productivity before getting the basics right.”

SOUTH AFRICA HAS WORLD CLASS GAS ENGINE COMPONENT REMAN SKILLS

Leveraging gas as a power source is an exciting prospect for Africa, and offers not only reasonable costs but will have a lower environmental impact. While natural gas is generally a clean burning fuel, gas generated from landfill sites is considered a much harsher application for engines.

Andrew Yorke, operations director at Metric Automotive Engineering, says this is because it is difficult to control the level of contaminants in gas that emanate from landfill sites. 

Yorke says that the relatively poor quality of gas requires advanced ignition monitoring systems in the engine. In addition, the wear rates remain high due to the highly abrasive post-combustion residue, despite filtering of the gas.

“This means that gas engines operating in these applications require more frequent maintenance and the service intervals will also be reduced,” he says. “As a comparison, with natural gas cylinder heads will need to be replaced every 20,000 to 30,000 hours, while with engines burning landfill gas attention will be required as early as every 5,000 hours.”

He notes that there is no real cause for concern as South Africa has a world class engine component remanufacturing capability in Metric Automotive Engineering. Ready access locally to the requisite skills and cutting edge equipment needed to optimise the lifespan and reliability of these gas engines is a major advantage to these industries, he says. 

The company has been in operation for more than 50 years, with its decades of experience underpinning the remanufacturing of both diesel and gas engine components to meet the exacting original equipment manufacturer (OEM) standards.

Yorke says that Metric Automotive Engineering has already been conducting work for customers in the both the natural gas and landfill gas segments, where the generating capacity of the engines is usually between 1 MW and 10 MW. 

The company also provides customers with service exchange units. This not only enhances efficiencies in the maintenance process and reduces downtime, it also allows customers to have remanufactured components such as cylinder head assemblies readily available when worn components need replacement.

HILTON HOTEL UPGRADES WITH GRUNDFOS PUMP SET

A Grundfos Hydro MPC-E booster pump set with four 7,5 kW motors and CIM 500 control system installed at the Hilton Hotel in Sandton is delivering both environmental and cost-saving benefits.

“The new energy efficient system has helped reduce our carbon footprint and combat climate change – an important part of our social responsibility,” says Charmaine Spasojevic, chief engineer at the Hilton Hotel.

Spasojevic says the cost saving will be achieved not only through the consumption of less electricity, but through reduced maintenance. This is due to the elimination of the separate variable speed drives (VSDs), meaning fewer items of plant to maintain. Management at the 12-floor, 329-room hotel will also have real-time access to operating data from the pump set. 

“The system integrates seamlessly with our building management system (BMS), allowing us full control over our service,” she says. The Grundfos CIM 500 control system allows the hotel to monitor various aspects of the pump set, including its running hours, energy consumption and discharge pressure, as well as any power supply problems or water shortages. 

According to Errol Dobson, Grundfos SA’s team leader building service, the Grundfos Hydro MPC-E maintains a constant pressure through continuous adjustment of the speed of the pumps. 

“The system’s performance is therefore adapted to the demand through the pumps being cut in and out as required, and through parallel control of the pumps in operation,” says Dobson. “Constant pressure control is also ensured through the continuous variable adjustment of the speed of each individual pump.”

The solution was designed and supplied in collaboration with Johan Truter, sales director at API Pumps Gauteng, and installed in June 2020. Grundfos service engineer Marius van Wyk commissioned the pump set, which will be serviced and maintained through a Service Level Agreement (SLA) with Grundfos.

MULTOTEC PIONEERS INTRICATE DESIGNS IN SOLID CERAMICS

An innovative ceramic-based solution from Multotec has opened the door for a range of componentry to be shaped using pressed alumina ceramics – for high wear resistance and longer wear life.

According to Boyd Butterworth, sales engineer at Multotec Wear Linings, the opportunity arose when a chrome smelter in the Steelpoort area of South Africa’s Limpopo province was searching for a more cost-effective solution for certain wear parts in their rotary dryer multi-cyclone arrangement. 

“The customer initially required the fabrication and ceramic lining of steel components in the multi-dryer cyclones,” says Butterworth. “The units are employed in the process of drying chromite ore particles and other feed material on its way to the pelletising section of the plant.”

The units are essentially dust cyclones – rather than the process or separation cyclones that Multotec supplies – and are subject to aggressive wear. The feed to these multi-dryer cyclones typically consists of chromite ore, reductants such as anthracite, char, coke and coal and fluxes like quartzite, dolomite and lime. 

“The multi-dryer cyclone has four main components, made initially of steel and later lined with ceramics in response to the rapid replacement rate,” he says. “The wear rate is exacerbated by the high velocity of the material, which is required in order for it to remain in suspension while passing through the system.”

The customer’s eagerness to find a more effective solution allowed Multotec to present an unusual – perhaps unique – concept: solid ceramic components custom-shaped for this specific purpose. 

Butterworth notes that the previous installation of standard ceramic tiles by a competitor did not adequately protect the components from the highly abrasive material which, moving at about 18m/s, was still leading to frequent component replacements.

“Our proposal was to produce a solid ceramic blade and dome arrangement, as well as to provide the rest of the tube and inlet sections with engineered ceramics, installed at a very high standard,” he says. 

Paving the way for this solution was this local manufacturing facility’s highly specialised and innovative new fabrication technique.  The ceramics are shaped into various complex and intricate designs while they are in the ‘green phase’ of production, using state-of-the art CNC technology.

“Thanks to this technique , we can produce solid  alumina ceramic machine  components,” he says.

Butterworth concludes that the company’s research to date suggests that this might be the first time that components like these have been produced from pressed alumina ceramics – making them a pioneering achievement. 

RIGHT CHUTE DESIGN CAN SAVE HIGH CONVEYOR COSTS

Conveyor belts are high cost items in any bulk materials handling application, so it is vital that damage and undue wear is avoided through the correct design of transfer points.

“Where chute systems are not properly designed and manufactured, mines will invariably face sky-rocketing conveyor belt costs,” says Mark Baller, managing director of transfer chute expert Weba Chute Systems. “A custom solution, on the other hand, can reduce these costs by three or four times.”

Baller highlights that conventional chutes tend to allow run-of-mine material – often up to half a metre in size – to drop from considerable heights onto conveyor belts. This is a common cause of damage and significantly reduces belt life. Differences between the material’s velocity and the speed of the belt also aggravates this wear. In addition to frequent belt replacement or repair, mines are faced with the disruption of unplanned stoppages and the unnecessary cost of this downtime.

“The answer lies in a holistic chute design that controls the flow, volume and velocity of material,” he says. “This control is a key factor in reducing wear and tear on belts, while also cutting dust levels which are caused by the impact of falling material.”

Weba Chute Systems achieves this through sound engineering principles, in particular by building the ‘super flow effect’ into its custom-designed products. The customer’s application and environment are also studied in detail to ensure that each design is fit-for-purpose. 

“Our years of experience with transfer points have given us extensive insight into the range of data that we need for appropriately engineering the solutions we propose to customers,” he says. “This includes details of the product being moved and its consistency, the trajectory of the outgoing conveyor, and the transfer height.”

He emphasises that Weba Chute Systems conducts on-site assessments to check that the data being used is correct. The company uses 3D scanning and leverages this data using sophisticated 3D software for the assessment of information ensuring that designs are optimal and accurate. Discrete Element Method (DEM) simulation is also used as a verification tool.

“Many mines are inclined to underestimate the value that can be added to both their process efficiency and their bottom line by good engineering design. Like all other key equipment in a plant, chutes need to match precise operational requirements – hence the need for a customised solution,” Baller concludes.