Tag Archives: Weba Chute Systems

More Weba chutes set to arrive at Zimbabwe platinum mine

Comminution of minerals, Mineral processing, Mining equipment, Precious metals, , , , ,

South Africa-based Weba Chute Systems is set to provide 10 more of its custom engineered transfer chutes for the expansion of an underground crusher station at a platinum mine in Zimbabwe.

Overseeing the contract for Weba Chute Systems is Project Manager, Ted Cruikshank, who explains that the design, manufacture and delivery of the units is already 80% complete. Over the past 20 years, the company has installed approximately 70 chutes for this customer.

“The chutes being supplied in this latest contract will feed run-of-mine material from the ore pass to the underground crusher, as well as from the crusher to the outgoing conveyor,” Cruikshank said. “This has involved designing and building chutes ranging in height from two metres to six metres.”

Before the crusher, the chutes take large material of up to 650 mm in size from a vibrating feeder, at a maximum tonnage of 1,100 t/h. Other chutes take the feeder’s undersize, which is smaller than 180 mm in size, at 550 t/h. Some of the chutes will also be used in conveyor-to-conveyor applications; these feed 1,500-mm wide belts with up to 1,350 t/h of material with a maximum lump size of 250 mm.

“The abrasiveness of platinum ore makes our chute design philosophy – based on the cascade system – very important,” Cruikshank said. “Our use of dead boxes on the inside of the chute creates a layer of ore for the moving material to flow over – thereby extending the wear life of the chute itself.”

Replaceable lips on the dead boxes become primary wear parts, which can be easily and quickly swapped out at the necessary intervals. By controlling the flow of the mined and crushed material, the chutes facilitate smoother transition and central loading onto conveyor belts, in turn reducing wear, damage and spillage, the company explained.

“The chutes also include inspection doors for easy access during maintenance,” Cruikshank said. “To promote optimal uptime for the customer, we are also including a spare set of wearing lip liners for each chute. These are vital for securing the material layer, while ensuring that the dead box itself is protected from undue wear.”

Weba Chute Systems’ agent in Zimbabwe, the locally owned firm Hilmax, will supervise the installation of the chutes.

Weba Chute Systems wins retrofit design work at Mpumalanga coal mine

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When a coal mine in South Africa’s Mpumalanga province needed to replace its high maintenance conventional transfer chutes, it looked to Weba Chute Systems for the best custom-engineered design, the manufacturer says.

Weba Chute Systems is currently busy with designs that will pave the way for the retrofitting of over a dozen chutes at the mine. Eight of the units are silo discharge chutes, transferring coal from the operation’s run-of-mine feed to its coal processing plant. Another four chutes are to be replaced in the plant itself, while there is another chute located between two related feed conveyors.

“The main objective of the new bespoke chutes is to ensure stable supply to the plant, and from there to the nearby power station,” Dewald Tintinger, Weba Chute Systems’ Technical Manager and Designer, says. “The existing equipment is demanding too much maintenance, leading to unacceptable levels of downtime.”

The key to improved uptime and extended chute lifespan is the company’s flow control principles in its designs. The chutes in the plant, for example, must deal with oversize material of between 150 mm and 500 mm in size.

“Handling these large particles, chutes are exposed to high levels of impact and wear,” Tintinger says.“With the controlled flow philosophy of our Weba ‘cascade’ chute system, we control both the velocity and the impact.”

Commenting on other aspects of the custom designs, Tintinger says the transfer points will include features such as dead-boxes to create a lining from the mined material itself. This reduces the wear on the chute’s metal surfaces, extending the maintenance intervals and delivering more uptime. He highlights that the processing plant feeds the power station directly through two overland conveyors.

“This is a highly efficient model for delivering coal, but it demands that all elements of the materials handling system are working together,” he says. “Any disruption of coal flow caused by a transfer chute can cause costly delays, and render coal delivery unreliable.”

He notes that the mine has had good experience from the many other Weba chutes already installed at this operation, and is now standardising on this internationally accepted transfer point design for better results.

Designs and engineering are conducted in-house by Weba Chute Systems’ experienced team, using the latest software and finite element analysis tools for testing.

The design work is expected to be completed around the middle of 2022. Thereafter the mine will be in a position to contract the fabrication and installation work.

Botswana diamond mine feels the impact of Weba Chute Systems custom solution

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Faced with a challenge of large rocks in the run-of-mine (ROM) feed regularly damaging main support structures, chutes and a grizzly feeder, a diamond mine in Botswana reached out to Weba Chute Systems to design a solution to overcome this costly challenge, which included major safety hazards.

According to Hilton Buys, Regional Manager at Weba Chute Systems, the mine’s existing chutes at the ROM section were cracking and breaking under the barrage of heavy kimberlite rocks measuring up to 1 m in diameter.

“Even the robust grizzly feeder could not withstand the impact of these rocks, which were free-falling about two metres from an apron feeder before contact,” Buys said. “Apart from the costs incurred by this damage, the transfer points were posing a significant safety hazard to mine employees.”

The solution – designed and manufactured at Weba Chute Systems’ Wadeville facility – was a special four-tonne swing door in a discharge chute, feeding from the apron feeder to the grizzly. The heavy, fabricated door is strong enough to withstand the impact while absorbing the energy of the falling rocks before allowing them to drop onto the loading section of the grizzly. The feed can then move in a more controlled manner over the grizzly into the crusher below.

“The key principle was for the door not to give way easily, thereby reducing the velocity and momentum of the large chunks,” Buys said.

There was also a design requirement to accommodate the movement of smaller rocks. This was dealt with through the addition of a second door, to also ease these rocks onto the grizzly to ensure a more gradual feed into the crusher feed chute. The success of the design, which is based on the Weba Chute Systems principle of controlled flow, has been demonstrated in the chute’s ability to operate with very little maintenance, he says. The only components needing regular attention are chute lips and swing door rails.

“We also included some specific design elements in the crusher feed chute, by installing impact rubbers,” Buys said. “Any rocks that may diverge from the main flow stream will then strike this rubber, minimising the vibration and impact on the body of the chute and are still able to drop gently into the crusher.”

Following on the success of this design, the solution was repeated at other customers’ sites, including mines in the Northern Cape which experienced similar challenges.

Weba Chute Systems solves choking problem at Botswana diamond mine

Comminution of minerals, Diamond mining, Equipment maintenance, Mining equipment, Mining services, , , , ,

Weba Chute Systems has come to the rescue of a large Botswana diamond producer suffering from continuous chute maintenance with a customised solution that came with a 12-month guarantee.

This primary crusher discharge chute had been a headache for the company, with the crunch coming when, after considerable capital expenditure, the new conventional chute needed maintenance just six weeks after installation.

Hilton Buys, Regional Manager at Weba Chute Systems, said: “This could not continue and the mine needed a long-term solution which is why we believe they came to us for a proposal. Senior experts from our company visited the site to take a careful look at the conditions the chute needed to deal with, and we took our conclusions back to our design office.”

Among the challenges were large lump sizes in the ore stream, contributing to build-up of material in the chute and regular choking, Buys said. Also, while Botswana’s dry season is long, the rain that does fall causes considerable problems to the flow dynamics. The kimberlite on the mine – depending on which part of the pit it comes from – can become very sticky in wet weather, according to the company.

“We therefore had to pay particular attention to flow angles, and the design had to effectively accommodate both wet and dry conditions,” Buys said. The concept design – which included quick-release lips on dead boxes – was approved by the mine and the final design, manufacture and successful installation was conducted.

Adding to the complexity was that the feed end of the primary crusher was some 8 m below ground level, while the crusher itself stood about 10 m tall. The chute had to be positioned below the rock box, which stores the material from the crusher discharge, channelling the stream into the Weba chute at a transfer height of 9 m to the conveyor belt.

“The conventional chute also created excessive dust through uncontrolled rock velocity over this considerable transfer height,” Buys said. “By contrast, our chute’s controlled flow meant that the mine did not even have to apply its dust suppression system.”

After installation, Weba Chute Systems gave the customer a 12-month guarantee on this chute, as it does with all its new chutes. This guarantee, which comes with regular inspection reports, assures the customer that the performance will meet their expectations.

“These inspections allow us to monitor wear, so we can advise the customer on what action is required so that they can schedule maintenance and avoid unexpected downtime,” Buys said.

Installed in 2017, the chute is still operating with little maintenance, having been delivered at a highly competitive price compared to the one it replaced.

“Designing a long-lasting chute is not just about creating a box with some reinforcing where you think there will be wear,” Buys said. “It is an endeavour that must be scientific, based on in-depth analysis of material and flow conditions.”

Buys highlighted the importance of asking a range of technical questions about the specific application so the design answers those needs. The latest software and modelling tools are then applied by the Weba Chute Systems team to guide the most effective design.

Weba custom-engineered chutes cut the dust at platinum mines

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Weba Chute Systems says it has been able to demonstrate to platinum mining customers how its custom-engineered chutes significantly reduce dust at transfer points.

Using the latest dust measuring technology, the company has carried out tests at mines in South Africa and Zimbabwe to compare the impact of Weba designs on material flow and dust levels, Izak Potgieter, Systems Manager at Weba Chute Systems, said.

At the site in Zimbabwe, considerable dust levels were created at bunker discharge chutes. Material of up to 500 mm in size was moving through at a rate of 600 t/h.

“The material flow was the biggest factor generating dust in the conventional chute, as material was not flowing as evenly as it should,” Potgieter says. “This created a lot of energy for the dust particles to expand into the surrounding atmosphere.”

The installation of the Weba chute – with its engineered design for optimal flow control – reduced the dust levels by about 40%, according to the company.

“By controlling the velocity of material, the design not only cuts dust creation but also reduces impact and wear for increased productivity and less maintenance downtime,” Weba said.

At the South Africa operation, the tests were conducted at a transfer point in the milling plant where an average tonnage of 190 t/h was being moved. Despite the use of water sprays, the existing chute was still creating considerable dust. The installation of the Weba chute was able to reduce dust levels by 15%, according to the company.

“Dust levels have shown to have a serious impact on human health, especially smaller particle sizes of 0.3 micron,” Potgieter says. “Health effects of dust relate mainly to particle size and dust may contain microscopic solids or liquid droplets that are small enough to get into the lungs and cause serious health problems.”

Spores and contaminants associated with dust and aerosol can also adversely impact human health, causing a range of issues from respiratory infections to toxic exposure, according to Weba.

Weba’s custom-designed chutes find favour in Africa

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Weba Chute Systems’ Wade Vandenberg says mines across Africa are recognising the value of the company’s custom-designed chutes in controlling material flow, extending wear life and reducing maintenance downtime.

The South Africa-based company’s transfer point solutions have made their way into mines across Africa, from platinum to diamond operations, to gold, coal and copper mines.

In addition to mining hotspots including Ghana, Mali, the Democratic Republic of the Congo, Zambia, Zimbabwe and Botswana, Weba Chute Systems have been installed in countries like Tanzania, Mauritania and Eritrea, it says. Authorised Weba Chute Systems agents are deployed to support customers in key countries, while technical experts from the company’s head office in Germiston, Gauteng, South Africa, are on call to assist.

Vandenberg, Weba Chute Systems’ Technical Advisor, Africa, said: “Not only do these operations gain the benefits of controlled material flow in their operations, but they experience, first-hand, how our engineering design extends wear life and reduces maintenance downtime.”

He highlighted that better dust control – a key part of health and safety policies in the mining sector – is another important benefit Weba chutes bring to an operation.

“Our state-of-the-art digital engineering design facilities and expertise makes use of the latest technologies to simulate the specific material flow conditions in each customer’s application,” Vandenberg said. “This allows us to apply our philosophy that no two chute designs are identical, and to scientifically accommodate exact flow characteristics into our design.”

Discrete element modelling allows close control over the flow of material through the chute. This minimises turbulence, reducing the levels of dust created in the working area. It also cuts spillage levels, which, in turn, means a saving of valuable material and less time spent on cleaning activities.

Izak Potgieter, Systems Manager at Weba Chute Systems, said: “We work towards the ISO dust management standards, supporting our customers in managing health and safety in this critical area of transfer points. Our testing measures dust down to 0.03 micron particles, to make sure that our designs meet stringent health-related targets.”

Flow control also creates more material-on-material movement to reduce wear on chute liners, according to Weba. This ensures longer liner life when compared with that of conventional chutes. Custom design and use of simulation technology allow for the wear life to be carefully predicted, based on operating conditions, the company says.

Vandenberg said: “Our technical expertise and solutions-oriented approach mean that customers can always rely on us. When we commission one of our chutes, it is part of an ongoing productivity journey with our customer, no matter where they are located.”

Weba Chute Systems called in for Mexico gold tailings project

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As part of a significant investment to improve its processing facilities and enable the recovery of 40% of the gold that currently sits in its tailings as waste, a mining operation in Mexico called in a leading transfer point and chute systems equipment manufacturer to conduct a thorough assessment on the functionality of existing chutes in the plant.

Weba Chute Systems & Solutions, leveraging its knowledge of material behaviour in chute systems, was tasked with establishing the feasibility of introducing filtered tailings at a rate of 1,200 t/h onto the existing transfer system currently handling waste with a nominal size of 400 mm at a rate of 5,000 t/h.

While the intention is for the filtered tailings to be conveyed when the waste rock is available, it would still mean the same chutes would need to function transferring completely different material, according to Alwin Nienaber, Technical Director of Weba Chute Systems.

“Optimally, one should be able to assess a working transfer chute handling the actual material, however in the case of a feasibility assessment this is not possible, and we therefore started with a review of the test work and studies prepared by independent qualified professional materials handling experts.”

This was done by Weba Chute Systems & Solutions calibrating the material conditions and behaviour using discrete element method (DEM). Nienaber said: “Use of DEM allowed our technical team to model the interaction between individual particles and boundaries and, in so doing, to accurately predict the bulk solids behaviour.”

Access to DEM software allows engineers to predict bulk material flow patterns and flow rates as well as velocity patterns and dead zones within a transfer system, according to Weba. It also provides accurate information on particle distribution in segregation and blending and the impact forces on particles and boundary surfaces, showing wear patterns.

The feasibility assessment included the transfer of sedimentary dry tailings, sedimentary filter cake, breccia dry tailings and breccia filter cake. DEM modelling was carried out considering material on its own and conditions where blended material would be conveyed.

In total, there were four conveyor transfer points that had to be assessed. These included an inline transfer point, a 90° transfer point, a transfer from conveyor to radial spreader intermediate conveyor and then onto the spreader boom conveyor.

Weba Chute Systems and Kwatani save the day at South Africa gold mine

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Weba Chute Systems and Kwatani have come together to design and install ore silo chutes at a South Africa gold mine to reduce mill wear and other processing challenges caused by the uncontrolled flow of mined material into the mills.

The solution from Weba and Kwatani, a leading local manufacture of vibrating screens and feeders, must also deal with frequent large-size material as the mine has no crushing stage before the milling circuit, Weba said.

According to Weba Chute Systems Technical Advisor, Alec Bond, the over-feeding of material through the existing manually operated chutes is causing regular “mill vomit” in the mine’s four mills. The inconsistent feed exacerbates wear on mill bearings as the material’s weight shifts forwards and backwards inside the mill.

The waves of material causing the “vomit” carry insufficiently milled material out of the mill, including large chunks of rock. This leads to problems for the downstream mineral processing facilities, including inefficient recovery in flotation cells and even blockages in pumps, according to Bond.

“The challenge starts with the existing chutes needing constant supervision and control by operators, being opened and closed with a chain block device,” he says. “Our solution was to design a robust, self-controlling chute and feeder system that would ensure an even flow of material into the mills.”

He explained that the mine’s existing system has no means of closing the silo outlet; any maintenance at the chute area requires the emptying of the silo and the stoppage of the mill. Each of the four silos has three outlet chutes.

Weba Chute Systems Designer, Wesley Hunkin, says: “We therefore added a spile bar arrangement which seals off the silo. The Weba chute, which is choke fed, is placed under this installation. This allows the feed rate to be controlled by the Kwatani feeder, which has been integrated into the chute design.”

The vibrating action of the feeder controls the tonnage and feed rate to the mill, keeping the flow constant. New mounting structures have been designed to accommodate each chute and feeder. There will also be civils works below the silo to provide a solid foundation that absorbs vibrations from the feeder, according to the companies.

A serious challenge is over-sized rocks in the ore feed, which can be up to 800 mm in size. This makes it important for chute designs to accommodate the worst-case scenario of chutes choking, says Hunkin.

He highlighted that the flow of material is also controlled to prevent direct impact onto the conveyor belt feeding the mills, and to ensure central loading onto the centre of the belt.

“If the material from the feeder is biased to the one side, our chute brings everything to the centre of the conveyor,” he says. “This enhances the consistency of material flow into the mill.”

Bond emphasised that the customer motivated for a concept change to address the challenges being experienced with the silo feed.

“Given our materials handling experience, design expertise and high-quality local manufacturing facility, we were able to work closely with the customer and with Kwatani to turn this new concept into reality,” he said.

“Our solution promises direct savings in terms of mill bearings, as well as less mill downtime. There will also be significant gains in terms of recovery rates in the plant if the flow and size of milled material can be improved.”

Weba Chute Systems increases design accuracy with 3D scanning

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Weba Chute Systems & Solutions says it has leveraged the latest technology to ensure high-quality results for its global customer base.

Using 3D scanning technology during on-site assessments has enhanced the levels of accuracy which has, in turn, minimised rework costs in design and manufacturing, and significantly reduced downtime during installation, according to Managing Director, Mark Baller.

“Implementing 3D scanning technology to our capabilities two years ago enabled our on-site technical teams to obtain accurate measurements from a safe distance, and allows us to inspect and survey large infrastructure in detail,” Baller said. “The technology allows us to consider all elements in existing infrastructure and this plays an important role when replacing transfer points or chutes as we are able to create an accurate preliminary design and costing in the early feasibility stages of a project.”

Design engineers can use the data from modern laser scanners to superimpose this information on their design intent, according to the South Africa-based manufacturer of custom transfer points and chute systems. “This allows them to pick up any interference, existing defects, redundant elements, structural deformation and undocumented historical alterations made to the site’s infrastructure that may lead to problems during the design and execution phases,” Weba Chute Systems said.

From this data, taken on-site, Weba Chute Systems teams can generate 3D models specific to on-site conditions enabling accurate reverse-engineering to be done. Baller said it is not just the access to accurate measurements provided by the 3D scanning technology that makes this possible, but also the level of in-depth expertise and experience the company has garnered over its more than 35 years in operation.

“Many companies offer 3D scanning, but do not have the in-house ability that Weba Chute Systems does to process and effectively use the data in a mining engineering environment,” Baller said.

“As a market leader, that is one of our strengths; and comes from our continuous investment in upgrading our systems and work flow processes to ensure that we stay abreast of best practice.”

He concluded: “Leveraging this technology allows our engineers to get to the highest probability factor, so the project can be seamlessly executed and time overruns are not incurred during the constrained shutdown periods which are normal on these projects.”

Weba Chute Systems tackles size issue at Botswana diamond mine

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Weba Chute Systems recent solution at a diamond mine in Botswana has tackled the issue of large particle sizes to ensure more uptime for the customer’s operation.

The mine had been faced with replacing transfer chutes almost every three months, as they could not withstand the arduous operating conditions. Run-of-mine material with lump sizes up to 1,200 mm was fed via an apron feeder onto a grizzly feeder, with the oversize material reporting to the jaw crusher.

The large size of the lump kimberlite in this application – as well as material being uncontrolled – posed an ongoing challenge to the transfer system. Another challenge in this primary circuit was that the conveyor receives material from the grizzly underpan and jaw crusher discharge, and lack of material control had resulted in high impact onto the conveyor belt. This damaged the conveyor and caused considerable spillage, resulting in unplanned downtime as the conveyor belt had to be replaced just about every quarter, according to Weba.

“The added expenditure and lost productivity meant increased operating costs for the plant, and eventually led to a decision to address the total material transfer system. The technical team from Weba Chute Systems assessed the challenges being faced and, in close collaboration with the mine, engineered a material handling solution,” Weba said.

Dewald Tintinger, Technical Manager at Weba Chute Systems, said: “Dealing with challenging applications – and in particular uncontrolled material flow – is something we are known for; we are often called in to assist plants where a standard one-size-fits-all solution has proved inadequate to their specific material handling needs.”

According to Tintinger, standard solutions for transfer points do not consider factors such as lump size and material velocity, or the general arrangement of the transfer point and the relationship between the equipment that feeds and receives material.

“Custom-engineered transfer points, on the other hand, are designed to deal specifically with individual materials handling applications,” he said. “They offer major advantages to a plant, but these often only become apparent after the basic chute systems have failed.”

In Weba’s solution for the diamond mine, the transfer chute that moves material from the apron feeder to the grizzly feeder incorporates an innovative patented mechanism that overcomes the challenges of handling the 1,200 mm lump sizes.

Tintinger said: “An integral swing mechanism – engineered to guide these large lump sizes through the transfer point at a controlled velocity – reduces the impact on downstream equipment. The next chute in the process flow therefore no longer has to deal with excessive impact, as this has been addressed through the swing mechanism in the first chute. The material then flows through the grizzly discharge chute and reports to the crusher.”

The combination of an engineered transfer point – with the swing mechanism in this position – has drastically reduced high impact and excessive wear previously experienced, according to Weba. The chute’s longevity has been dramatically improved, and has not required replacement since its installation over a year ago.

The grizzly underpan chute system handles lump sizes of minus 250 mm and has been designed to accommodate this material. With a drop height from the grizzly feeder to the conveyor of about 7 m – and with lump sizes of up to minus 250 mm – this could become a challenging transfer point.

Tintinger said: “Applying an engineered transfer point solution here was critical to the success of this material handling operation. The chute design accommodates the material flow in such a manner that it is absolutely controlled and excessive damage is no longer caused to the receiving conveyor.”

The crusher discharge chute is the final of the four engineered transfer solutions; while the same engineering principle as the third chute has been applied here, the drop is not as far. The combination of these two chutes has significantly reduced material impact onto the conveyor and has substantially increased belt life.