WEBA SAYS NO SECRET TO GETTING REAL VALUE FROM CHUTES

General maintenance service providers often show little respect for the engineering design of specialised on-mine equipment, which can cost the mine dearly in the long run.

This applies as much to transfer chutes as to other mining infrastructure, according to Weba Chute Systems technical director Alwin Nienaber. The result of poor maintenance is usually that mining operations are compromised by unscheduled stoppages caused by equipment failure.

“The tragedy is that what generally drives mines to outsource maintenance to general service providers is an attempt to cut costs,” says Nienaber. “But the result is frequently the opposite – on top of which the mine’s production revenue is severely undermined by misguided attempts at cost-saving.”

He highlights that poor maintenance prevents chutes from delivering the value that the OEM has promised. In Weba Chute System’s case, its chutes are custom-engineered to suit the specific duty; any short-cut taken in maintenance – for instance, in terms of the materials used – will reduce performance and lifespan. There could be costly operational consequences, such as added impact on conveyor belts and resulting damage. More spillage could occur at the transfer point, along with higher dust emissions – all requiring urgent attention.

“OEMs bring a wealth of highly-focused experience with each product, adding tangible value to the mine’s overall efficiency, safety and profitability,” he says. “This expertise translates into smoother mining operations, as we have so much practice in our field that we can assure the customer of the outcome of every intervention.”

This reliability is a key part of the value offered, and extends to the timeous sourcing or delivery of spares and the convenient scheduling of the necessary maintenance. 

“We have witnessed first-hand what can happen to plant availability when critical components like chutes are not well cared for,” says Nienaber. “By collaborating with a customer on maintenance, we helped keep plant availability as high as 98%; when the mine opted for a general contractor to save costs, that availability dropped to below 90%.”

A performance deterioration of that magnitude could be fatal for a mine, Nienaber warns, while the amount saved in operating expenditure was minuscule, and was far outweighed by revenue losses.

“When Weba Chute Systems maintains its own equipment, we ensure the high standards to which they are designed and manufactured,” he says. “That is how we keep our word and earn customers’ trust.”

ASSESS RISK, PLAN AHEAD BEFORE DECIDING ON PDS

As mines work to improve the safety of their trackless operations, the starting point remains a detailed risk assessment that will guide the correct selection of technology and proximity detection systems (PDS).

“There have been too many examples of mines incurring capital expenditure on PDS solutions that are not fit-for-purpose,” says Schalk Janse van Rensburg, chief technology officer (CTO) at Booyco Electronics. “More careful planning will ensure that the solution chosen can be well integrated into the mine’s operation.”

Janse van Rensburg highlights that PDS is a last resort in the risk management hierarchy, and that the mine safety regulations require a proper risk assessment to be done to indicate whether and how PDS will address the mine’s significant risks. 

Such an assessment needs to establish design guidelines for the mine, including site requirements for TMMs, segregation controls to prevent collisions, and operating procedures. Three more levels of operational discipline control in the use of TMMs – the authority to operate, fitness to operate and operating compliance – must also be considered. 

“If interventions at these six levels still cannot adequately mitigate the significant risk, then the mine must move on to consider the collision avoidance options at levels 7, 8 or 9,” he says. “At Level 7 the PDS will provide proximity awareness by alerting the driver, at Level 8 the system will advise on action to be taken, and at Level 9 the system will slow or stop the machine through engineering control.”

Assisted by the TMM operating scenarios outlined by the Earth Moving Equipment Safety Roundtable (EMERST), mines must be able to provide PDS suppliers with a tabulated scope of what they require. Once a supplier has provided a credible proposal in response, he urges mines to effectively test the solution before making a final decision. 

“The process of installing PDS systems in a mine TMM fleet, and ensuring that operators use the system well, must also be well planned and carefully rolled out,” he says. “The Booyco Integrated Approach includes the technical collaboration with OEMs and on-mine staff, and working closely with operators and management alike to ensure their buy‑in and co-operation.”

APEX STRIP CURTAINS STOPS COLD AIR IN ITS TRACKS

Apex General Purpose Strip Curtains are an inexpensive way to cover a door opening and prevent the ingress of hot or cold air, dust and other pollutants while still allowing easy passage for both personnel and vehicular traffic. This product is ideal for installation in small, medium and large openings. 

Manufactured from specially formulated PVC material that does not become brittle with use, Apex General Purpose Strip Curtains are transparent for optimum visibility and safety. This is an important factor when both people and vehicular traffic use the same entrances and exits. 

This locally manufactured strip curtaining product is best known for its patented Balledge® design which, while providing an effective thermal seal, parts easily under pressure to allow people and goods to move through unhindered.

Wim Dessing, sales executive of Apex Strip Curtains & Doors, says that the Balledge® design ensures that the individual strips do not snag or scratch goods or people moving through the opening. This feature also strengthens the strips ensuring a longer life even in the harshest applications. 

Apex Strip Curtains are generally used to prevent the ingress of hot or cold air, depending on the season, and this is considered important as comfortable employees are more productive. This, Dessing says, is especially true when hot air is trapped in a warehouse or manufacturing facility causing excessive heat build-up. 

Apex Strip Curtains & Doors was the first company to locally manufacture general purpose strip curtaining in South Africa.

MULTOTEC’S NEW SPIRAL FOR RETREATING ULTRA-FINES

Multotec has taken another innovative step to help customers recover more of their valuable ultra-fine material so that it does not go to waste in the discard.

As a leading designer and manufacturer of spiral concentrators, Multotec has released its UX7 spiral which focuses on recovering material in the particle size range of 75 microns and smaller. Refentse Molehe, process engineer at Multotec, says the success of the Multotec UX7 is based on extensive in-house test work, which has led to improvements and around 13% better recovery.

“Much of the testing was conducted on chrome, manganese and iron ore, but the UX7 spiral can be as easily applied to copper, platinum and other metals,” says Molehe. “This is an exciting development for the sector, as we have seen growing interest from our customers in gaining financial value from material which has traditionally ended up in tailings storage facilities.”

She notes that efforts to improve the recovery of ultra-fines have used a range of technologies, but spirals have always been regarded as a highly reliable and energy efficient solution. Multotec’s continuous improvement of its spiral technology to suit customer needs now opens the door for customers to cost effectively re-treat their tailings dams to recover valuable ultra-fine material. 

“In addition to its ability to recover ultra-fines, the Multotec UX7 spiral benefits from the various advantages shared by spiral concentrators,” she says. “These include the lower environmental risk and cost due to the absence of chemicals, and the low maintenance of this technology as a result of having no moving parts.”

Multotec’s decades of on-the-ground experience in mineral processing – and its depth of expertise in a range of related disciplines – equip the company to provide a customised, full flow sheet solution. Molehe emphasises that each application of the Multotec UX7 spiral will be based on an in-depth understanding of the customer’s operating conditions, fine-tuned by extensive testing of material to ensure the optimal result.

“Once we can confirm that the UX7 spiral is the appropriate solution for the customer’s operation, then we build in the throughput and capacity requirements and accordingly design the flowsheet to accommodate the specifications to be achieved,” she concludes. 

BRAVO PUMP PUSHES OUT CONTENDERS IN DENSE SLURRY WORK

Competitors are feeling the heat from the hard-working Grindex Bravo 600 submersible slurry pump, which has replaced under-performing products at two mine sites in Limpopo and North West provinces recently. 

The attraction, according to Jordan Marsh, sales manager at Integrated Pump Technology, has been the Grindex Bravo 600’s reliability and efficiency. This is due largely to its innovative cooling jacket between the outer casing and the motor.

“Mines have a frequent requirement for a hard-working pump to transfer slurry from process tanks, where levels change quickly and the material often becomes quite viscous,” says Marsh. “In these dry-bed applications, many pumps struggle with the density or even burn out when no longer submerged.”

The Grindex Bravo 600, though, has proven ideal for these applications, being supplied in South Africa as standard with a glycol-filled cooling jacket to keep its temperature down. This allows it to function reliably even when exposed above the slurry level.

“Plant operators are not always able to be present to check the levels in these tanks, or to add water to dilute slurry, so the specific gravity of the material can rise considerably,” he says. “This is where the Grindex Bravo 600’s agitator comes into its own, agitating the solids into suspension for easier removal. It even handles particle sizes up to 40 mm.”

To demonstrate the pump’s performance under these arduous conditions, Integrated Pump Rental offers mines a trial unit to run over an extended period. These tests are now resulting in purchases, says Marsh, after the customer is satisfied that the pump delivers. Both the impeller and casing are manufactured from hard iron, making for a robust product with long working life. 

“This 22 kW pump also punches above its weight in terms of output, achieving the same performance as our competitors’ 30 kW pumps,” he says. “This makes the solution energy efficient, saving mines on electricity costs.” 

Integrated Pump Technology has been distributing Grindex pumps in sub-Saharan Africa since 2014. So confident is the company about these advanced workhorse pumps, that the company offers a 30 month warranty on the units. Its well-equipped engineering facility in Jet Park undertakes maintenance and repairs to OEM standards.

PUMPING RESPONSIBLY THE ONLY WAY TO CONSERVE GROUNDWATER

As South Africa increases its use of boreholes to meet growing water needs, users must pay more attention to monitoring and controlling how much groundwater they pump or these resources could be rapidly depleted.

This is according to Stephan Venter, Grundfos product manager water utilities for India, Middle East and Africa, who has been extensively involved in providing pumping solutions for borehole users. 

“The main risk when municipalities, businesses or households make use of groundwater resources is that their extraction from boreholes could exceed the recharge rate of the aquifer,” says Venter. “To avoid this, users need to gather a great deal of information from the start – it’s more than just drilling and pumping.”

An important aspect of ensuring the sustainability of a borehole, he says, is the correct sizing of the pumping infrastructure. This requires data including the borehole’s safe yield, the dynamic water level, the required lift above ground, discharge ratio, friction loss in piping, flow demand and well size. 

He notes that while larger water projects will usually employ the services of a qualified hydrogeologist to generate the necessary data on the aquifer, many smaller users simply proceed with minimal information. 

“This makes it difficult to put the borehole on a sustainable footing,” he says. “Lack of investment in the monitoring equipment also creates challenges in controlling the water abstraction adequately.”

He highlights the importance of taking a conservative view on what levels of extraction the aquifer can accommodate. Even when yield testing is conducted, for instance, there could be other users of that particular aquifer who are not pumping at the time of the tests – leading to an over-estimation of yield capacity.  

“Just to be safe, I tend to advise the user to size their pumping equipment at only 50 to 60% of the borehole’s safe yield,” he says. “This reduces the risk of over-pumping, through which they could possibly even lose this valuable groundwater source altogether.”

There is no substitute for constant monitoring, however, and Venter emphasises the value of digital technology in collecting and transmitting data to keep users informed. Many users still use a manual inspection method to check the level of the borehole and the condition of the pump, but the most effective way is through electronic equipment linked to online platforms.

“This provides updated information at the click of a button, either through a SCADA system for larger users, on a standard computer or even on a mobile phone,” he says. “Monitoring and measuring our groundwater resources is vital in a dry country like South Africa, especially as we work towards becoming more responsible water users.”

Further challenges for borehole users include the unreliable power supply and the rising cost of the electricity required to pump water. Fortunately, solar power generation technology has improved in leaps and bounds, says Venter, and has been well leveraged by borehole pump manufacturers. 

“Solar power now allows water to keep flowing even when mains power goes down,” he says. “The development of high-efficiency pumps – combined with technology like permanent magnet motors and variable speed drives – can reduce pumping costs and ensure constant supply.”

He says that specialised software developed by Grundfos – the world’s largest pump manufacturer – even allows users to go online and select the ideal pump model to suit their borehole specifications, helping to make the most responsible use of the country’s scarce groundwater resources.

DRY-TYPE TRANSFORMERS FROM TRAFO IDEAL FOR COAL MINE

Trafo Power Solutions has customised two dry-type transformers for a coal mine in South Africa’s Limpopo province, allowing the units to be fitted into existing enclosures while meeting the customer’s demanding duty requirements.

“While we would normally supply the transformer together with its enclosure, we are also able to design the solution according to the dimensions available on site,” says David Claassen, managing director of Trafo Power Solutions. 

This required one of the transformers – a specialised 3900kVA unit – to be copper-wound to achieve a smaller footprint suitable to the space constraints without compromising the technical performance. With 11kV capacity on the primary windings, this transformer included four separate secondary windings – for 1810V, 1515V, 1360V and 1210V output respectively. 

“Being located outdoors on a coal mine, the transformer had to be well protected from fine dust and moisture, requiring a specially designed IP54 enclosure,” says Claassen. “At the same time, the transformer’s large size meant substantial heat loss, which needed to be extracted from the enclosure. The design therefore included an air-to-air heat exchanger to recycle cool air in a closed loop.”

The second transformer supplied to the mine was a 1600kVA unit for indoor application, stepping down from 11kV to 550V. Working closely with transformer repair experts Koratech Services, who applied certain modifications to the enclosure, Trafo Power Solutions was able to meet the dimensional and electrical requirement of the application – complete with control and protection system.

“Underground mining often presents space constraints which have to be considered in the design of the transformer or the miniature substation,” he says. “With our expertise and our strategic partnership with leading Italy-based manufacturer TMC Transformers, we can readily cater for these conditions.”

He notes that Trafo Power Solutions also supplies dry-type transformers to the marine industry, which requires not only that transformers can be safely employed indoors, but that they often be accommodated in cramped spaces. This experience enhances the company’s technical capability in underground mines. 

Claassen highlights that both transformers were ordered during the tight Level 5 Covid-19 lockdown in South Africa. Despite similar restrictions in Italy, TMC Transformers proceeded with manufacturing, running a 24-hour, three shift operation to ensure the required social distancing. 

“The high level of collaboration with our strategic partner allowed us to design, build and supply the transformers despite the Covid-19 disruption in 2020,” he says. 

Claassen says the dry-type transformer is ideal for both hazardous and non-hazardous areas of coal mines, as the absence of oil as a coolant makes the solution much safer. There is also much less maintenance required on dry-type transformers.  

POPULAR VSI CRUSHER JUST GOT EVEN BETTER

Continually advancing its crushing technology, Pilot Crushtec International has released its new Pilot Modular VS100 vertical shaft impact (VSI) crusher for tertiary and quaternary applications.

The Pilot Modular VS100 is a remodelled and improved version of the company’s popular entry-level Pilot Modular AC06 VSI crusher, according to Francois Marais, sales and marketing director at Pilot Crushtec. The AC06 has, for over 25 years, been successfully serving the aggregate and mining sectors with hundreds of units in the field both locally and internationally. 

Advanced materials and manufacturing methods have enhanced the Pilot Modular VS100, while it has retained the functionality and reliability of the tried-and-tested AC06 model. The versatile crusher is used mainly for producing sand and fines, and for enhancing the quality of aggregate.

“Among the features of the new VS100 are elements that make for a safer working environment,” says Marais. “These include a new inclined staircase, and a three-sided platform that is both non‑slip and chemical resistant.”

He emphasises that this high performance machine is packed with years of experience and know-how. The hydraulic pack both opens and automatically rotates the lid, revealing the modular rock chamber and rotor. The jib crane is installed as a standard item, for safe removal of the rotor. 

“The modular rock chamber allows you to go from autogenous crushing to an anvil ring crushing configuration, and is designed for efficient rock-box build-up,” he says. “The VS100 is also future-proof – with the option of two rotor sizes, five motor sizes, five rotor speeds and a rotor by-pass system.”

Marais explains that these options allow plant capacity requirements to be optimised with economical power consumption, making the unit versatile enough to allow upgrades as plant production requirements increase. 

“Once you start the crusher and the material pours into the newly designed omni-directional feed chute, you notice how smoothly the new advanced vibration isolation keeps the plant running smoothly,” he says.

The new-generation triple bearing, grease lubricated cartridge has an optional Auto Lube system to facilitate regular lubrication for added reliability, while the modular serviceable rotors reduce operational costs. Once the worn wear parts have been replaced – and correct tip material selected to suit the stone – the rotor can be balanced using the balancing kit provided. Pilot Crushtec SupportLink technicians are available to train customers’ maintenance teams during commissioning, ensuring smooth and cost-effective operation into the future.

“Overall, the new Pilot Modular VS100 is the complete package,” says Marais. “With its improved safety features for overall compliance, this brand new design allows operations to increase tonnages from 10 tph to 100 tph, depending on the application.” 

He also points to the unit’s ease of maintenance, made possible by the smart design and the simple operations of the crusher. These factors make the new Pilot Modular VS100 a wise and operator-friendly investment for any operation making use of VSI crushing. The skid-mounted module requires only a level compact surface for installation, and no civils infrastructure.

WEBA FORGES GREEN PATH TO THE FUTURE

A new 390 panel solar plant at Weba Chute Systems’ Germiston facility is now making an active contribution to the South African economy’s environmental protection and energy efficiency efforts.

As part of its green-future strategy, the transfer point specialist commissioned a roof-top solar energy system in December 2020 as part of its integrated response, says Izak Potgieter, ISO systems manager at Weba Chute Systems.

“With a capacity of 160 kW – calculated on 85% performance – the system meets most of the energy requirements of our workshop and offices,” says Potgieter. “This takes considerable pressure off the national grid, while also allowing us to feed power back into the system when there is excess.”

The impact in the first couple of months of operation has already been substantial, he notes; the 62MW generated by the solar panels represents a reduction of about 25 tonnes of carbon dioxide emissions that would have been produced from coal fired power. Other elements of the strategy have included energy efficiency interventions such as installing LED lighting in the workplace, and the continuous monitoring of heating, ventilation and cooling (HVAC) systems to ensure moderate use. 

“Our environmental strategy is also designed to address stakeholder pressures and market opportunities,” he says. “While there is no facility yet for us to be reimbursed for the electricity that we feed back to the grid, we believe this to be an important corporate contribution at this time. We are also building up carbon credits that may be traded with other companies at a later stage.”

Potgieter highlights that the company’s approach is based on eight sustainable business practices, which include partnering with employees, conserving water and electricity, developing a recycling programme, and prioritising the management of chemicals.

“We are keenly aware that our environmental efforts are part of the broader commitment by the mining industry towards a more sustainable future,” he says. “We therefore pride ourselves on making a positive contribution to the sustainability of the mining supply chain.”

Weba Chute Systems measures its corporate environmental performance against all its impacts on the natural environment – including resource consumption, pollution, waste generation and energy use – to reduce the effect on climate change.

ZEST WEG GIVES MOTOR USERS ANOTHER EFFICIENCY BOOST

In the face of rapidly rising electricity costs in South Africa, Zest WEG is phasing in IE4 super‑premium efficiency motors in its WEG W22 range from April 2021 – which will save on customers’ bottom lines and help reduce the load on the national grid. 

According to Fanie Steyn, electric motors manager at Zest WEG, 2021 will see local energy prices rising above R1/kWh for the first time. This makes it the ideal time for the introduction of WEG IE4-rated motors, which will be available in the size range between 37 kW and 375 kW.

“Unlike many countries around the world, South Africa has not regulated the use of energy efficient motors at the level of IE2 or IE3,” says Steyn. “Nonetheless, we have taken the proactive step of making the IE4 level of efficiency available to customers at no premium on the IE3 units.”

Some years ago, Zest WEG introduced its WEG IE3 motors to the country at little or no additional cost relative to its IE2 motors, with the same goal in mind: making both customers and the country more energy efficient.

Specified under the International Electrotechnical Commission (IEC) 60034-30-1:2014 standard, IE1 refers to standard efficiency and IE2 to high efficiency; the IE3 and IE4 ratings are for premium efficiency and super-premium efficiency motors respectively.

“The efficiency of 96.3% on an IE4-rated 110kW motor, when compared to 94.1% on an IE1-rated motor, can save users hundreds of thousands of rand in energy costs over a 10 year period,” he says. “Not only will these IE4 motors be more cost effective to run, but they have been designed with a number of new features that bring considerable benefits.”

Steyn emphasises that WEG IE4 super-premium efficiency motors meet IEC efficiency levels when running on 50 to 100% of load; efficiency is kept constant, which saves energy and ensures minimal losses through various loading points. The innovative frame design also allows maximum heat dissipation.

“Motor frame design plays a crucial role in thermal performance, as it is responsible for the outward transfer of heat generated inside the motor,” says Steyn. “Running cooler means that our motors have increased life spans, allowing Zest WEG to offer a five year guarantee on our WEG W22 electric motor range.”

The motors’ increased mechanical rigidity – achieved by integrating the front and rear feet sides – affords easier installation, higher mechanical stiffness and improved distribution of the mechanical thrust imposed by the load.

“As a first of its kind, our flexible terminal box mounting means reduced inventory and quicker modification,” he says. “The terminal box can be rotated in 90° increments to facilitate supply cable connection orientated to the front, rear, top or either side of the motor.”

In addition to the benefits brought by WEG super premium efficiency motors a substantial increase in energy savings can be reliably achieved using WEG Variable Speed Drives (VSDs), which comply with the European Extended Product standard EN50598. This ensures the system efficiency of the motor and VSD combination. As an additional feature, WEG VSDs have energy savings settings which can be user activated, achieving an automatic saving under any reduced load conditions.

“We are excited to build on the phenomenal reputation of the existing WEG W22 electric motor range by offering an even more efficient motor that is truly “next level” state of the art in electric motors, having the same rock solid quality and reliability,” Steyn concludes.