Smart high capacity conveyor systems push capacity limits

The mineral extraction process, which could take place by underground or open-pit mining methods, is only the beginning of the supply chain. Once the mined ore or coal reaches the primary crusher, the operation relies on a network of material handling systems, most often conveyors, to move materials from one location to another.

Today, more sophisticated drive systems are increasing capacities while reducing energy consumption per ton moved. Engineers are working wonders with conveyor systems that allow them to traverse all types of terrain. A better understanding of data is allowing designers to model and evaluate modern material handling systems.

Even large gearless drives for mills are now commissioned remotely. (Photo: Siemens)

The Digital Transformation of Mining

COVID-19 and its impacts significantly accelerated the acceptance of digital tools and work practices across the mining industry during 2020. While travel restrictions and safety concerns may eventually abate thanks to an influx of vaccines, the realization of new, more efficient ways of working, along with better process control and the possibility for more productive operations mean that this trend has likely changed the way businesses in the sector operate forever.

Christian Dirscherl, vice president for mining, excavation and transport at Siemens, discussed some of the changes that Siemens has seen. “In the last 12 months, we have faced COVID challenges, like everyone else, but we achieved our targets nevertheless,” Dirscherl said. “We did see impacts on plant setups, but we’ve been very successful with remote commissioning, for example, for autonomous stockyards and gearless mill drives. With a lot of these projects, we had planned commissioning pre-COVID and there was no way we could have foreseen that happening, so we had to adapt quickly. Most of our teams work remotely now, and commissioning and supervision services for all drives, electrification and digitalization projects are carried out remotely.”

According to a study published in October 2020 by McKinsey & Co, the COVID crisis has accelerated the digitalization of most companies’ customer and supply-chain interactions and of their internal operations by three to four years. And the share of digital or digitally enabled products in their portfolios has accelerated by seven years.

“I absolutely see that in the mining industry,” Dirscherl said. “Mining companies are still very conservative when it comes to innovation and digitalization, but they are becoming more open. That’s partly because of how remote most mine sites are; with current travel restrictions, there’s just no way of bringing technology specialists safely to site for commissioning or troubleshooting.

“And it’s not just a challenge for mining companies, safety is the most important area for Siemens. We can’t send someone to a site if we don’t know what the local situation is, and we want to know that, should that person fall ill during the trip, they will receive the best medical care. There is a lot of risk management involved.

“Also, to travel to different countries often requires a quarantine period when you arrive and when you return. Suddenly, two weeks of commissioning work requires four weeks of quarantining, too. That has to be factored in.

“We’re doing as much as possible remotely across all our divisions, including drives, digital, electrification,” Dirscherl explained. “For instance, we’re commissioning systems via VPN access, and even supervising people on site using augmented reality glasses, or using video communication systems to do consulting jobs from home.”

In line with this shift and, as mining companies also try to minimize their own number of staff on site, Siemens has seen increased interest in its autonomous mine management solutions, asset health analytics (AHA) — particularly for mission critical pieces of equipment like grinding mills, conveyors, and mine hoists — and in manufacturing execution system (MES) inquiries.

“Digitalization has been key in all industries over the past five years, but it requires more than just IT and automation,” Dirscherl said. “It also requires commitment and strategy, and what we’ve seen recently is more mining companies making that investment to truly become part of Industry 4.0.

“Solutions like our material tracking and management (MAQ) for autonomous stockyards deliver more than just process improvements. By removing people from harm’s way, they also improve safety on-site and eliminate the possibility for human error; machines and algorithms can fail, but human failures happen much more frequently.

“They also provide the chance to improve the quality of the product. For example, we’re now looking at using MAQ to blend copper ore; that wasn’t a discussion before.”

AHAs are also becoming more important. The unexpected failure of a critical piece of equipment like a hoist or mill, can, in some cases, cause hundreds of millions of dollars of damage through down time and lost product.

With many experts unable to travel to sites for repairs or troubleshooting, it’s more important than ever to prevent failures, schedule shutdowns well in advance and put proper planning around them.

“Overall, there are still new projects popping up and we see a positive impact on inquiries at the moment, especially for copper and gold projects,” Dirscherl said. “We’ve recently added another reference for our MAQ solution in Europe (autonomous stockyard management), a larger digitalization and automation project in Europe, and a large electrification project in North America.

“Everyone’s talking about becoming carbon neutral, from companies to governments. To make that happen and to meet the targets that many European countries have set around electric vehicles, will require a lot of new infrastructure.

“There is a lot of uncertainty at the moment with COVID but, on the whole, the future looks very promising.”

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The Prairie Eagle mine in Illinois is the largest coal mine of Knight Hawk Coal. (Photo: BEUMER Group)

Perfecting Storage and Stockpiles

At hard coal operations, material is temporarily stored in stockpiles and then continuously fed to be processed, as needed. The design of the depositories must therefore ensure constant filling and reliable emptying. The required capacity is determined based on the incoming and outgoing conveying flow. Different stacking and reclaiming options as well as various layouts for the stockpiles are also needed.

BEUMER Group offers a comprehensive product and system solutions portfolio to customers in the coal mining industry, including engineering expertise for stockpiles as well as the required components, such as stackers and reclaimers.

The company’s conveying technology includes closed pipe conveyors and open troughed belt conveyors that can be adjusted to the respective situation.

Drone technology is also being used more frequently during project planning, implementation and documentation to optimize the design phase. The recorded aerial photos are rectified with regard to their perspective and evaluated photogrammetrically. The software calculates a point cloud in order to generate 3D models from the 2D views, i.e., digital terrain models. Stockpiles can now be greenfield and brownfield developments.

Andrea Prevedello, system technology global sales director at BEUMER Group, explained: “We have some major customers with very interesting projects in this sector including the Prairie Eagle mine in Illinois, the largest coal mine of Knight Hawk Coal. The company produces approximately 5 million tons of coal annually, of which more than 80% is processed and delivered in Prairie Eagle.”

The management team at Prairie Eagle was looking for a more sustainable operating solution and turned to BEUMER Group for help.

“We provided an overland conveyor that transports the coal from the mine to the main processing plant,” Prevedello said. “Our conveyor helps the company to considerably reduce its ecological footprint. With this technology, Knight Hawk can significantly reduce its long-term environmental impact compared to using truck transportation.”

BEUMER not only supplied the conveying solution but also supported the mining group in building a stockpile for hard coal.

“The requirements for storing coal are obviously very different from other materials,” Prevedello explained. “Some of the important requirements change if the stockpile is covered and if explosion-proof equipment is needed. Hard coal is very susceptible to spontaneous combustion, which is why the height of the stockpile must be in certain cases limited.”

Depending upon the customer, stockpile dimensions and design can vary. Two layouts are generally available: circular and longitudinal.

“The dimension and design depend upon the purpose of the stockpile,” Prevedello said. “Space availability and possible future expansions are also critical factors.”

The application must also be considered: does the customer want to store the bulk material temporarily, then continuously feed it for further processing, like Knight Hawk? If so, then longitudinal stockpiles are often the best choice. The irregular flow of bulk material arrives at the stockpile and can then be continuously introduced to the process. The stockpiles can also be extended, if necessary.

Once the layout of a coal stockpile has been decided, the next task is to stack the bulk material efficiently. For this, BEUMER Group provides components such as stackers.

“Depending upon their mobility, systems can be categorized into three groups,” Prevedello said. “The stacker can be stationary, travel on rails or be circular with endless movement. If the machine is circular with endless movement, it is positioned on a column in the center of the stockpile. Over a conveyor bridge installed above the stockpile, the material is transported directly into the axis of rotation of the stacker and from there distributed centrally. Depending on the stacking method, the boom conveyor can be fixed, or it can be lifted and tilted.”

The stacking method of choice depends on whether the bulk material is only temporarily stored or if it also needs to be blended.

“For simple stockpiling without blending, we can use the ‘cone shell method’ where the stacker only moves up and down, without slewing,” Prevedello said. “The stacker design can therefore be much simpler.”

This method works for longitudinal as well as circular stockpiles. However, for blending bulk material, the chevron method is more suitable. In this case, the boom of the stacker starts in its lowest position. The first row of material is deposited in the center of the stockpile with the following rows layered on top of it. In longitudinal stockpiles, the stacker usually moves in a tilting and slewing motion, whereas in circular stockpiles, the stacker moves in a circulating and luffing motion.

Prevedello explained that the perfect system solution requires holistic optimization of the stacker and reclaimer. Reclaimers, such as side reclaimers or bucketwheels, remove the material as necessary and the best option for the customer again depends upon the stockpiling task at the end.

Side reclaimers work for both types of stockpiles — longitudinal or circular — because the bulk material can be reclaimed from the front or the side. When reclaiming from the side, scraper chains move the material on a belt conveyor. Front reclaiming usually uses a rake that pushes the material on to a scraper chain using small side-to-side movements before it is transported further to the conveyor.

The advantage of front reclaiming is that material is reclaimed from the entire cross-sectional area. Bucketwheels are mainly used when the bulk material, especially in large quantities, needs to be blended.

Each operator has their own very specific requirements for stockpiling and stockyard machines. For instance, BEUMER engineers recently delivered a solution for a customer in the energy industry, which included several pipe conveyors and a ship loader. The system was tailor-made to withstand the violent gusts of wind that are often experienced at the site, and the steel structure was specially dimensioned.

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BeltGenius is used for monitoring, benchmarking and optimizing belt conveyors and conveyor systems. (Photo: Voith Turbo)

A Digital Vision for the Entire System

Digitalization and electrification have been a key part of Voith Turbo’s growth and development strategy for some time, and 2021 will be no different.

“Concerning the range of products at Voith, we have years of experience when it comes to drive technology for various mining applications, including conveyors, crushers, armored face conveyors, bucket elevators, bucketwheel excavators, fans and blowers, mills, and stacker and reclaimers,” said Sebastian Steck, vice president for product management, Hydrodynamic Couplings at Voith Turbo. “Since Voith Turbo acquired ELIN Motoren, we now are able to even offer a bigger range of drive packages for mining.” Voith Turbo acquired ELIN Motoren GmbH, an Austrian manufacturer in the field of electric motors and generators, in April 2020. ELIN is active worldwide and supplies individualized solutions for various industrial applications, including mining.

In August, Voith Turbo also announced two new additions to its TurboBelt TPXL series of fill-controlled couplings. The range, which included 500 kW, 800 kW and 1,250 kW models, now boasts 315 kW and 2,500 kW versions, too. These combine hydrodynamics with intelligent control technology to further optimize the performance spectrum in challenging mining conditions.

“2020 saw further successful TurboBelt TPXL installations in Australia,” Steck added. “We further developed our CPC couplings for AFC’s for longwall mining in China, and Voith received the first order for BeltGenius. The technical acceptance on that is now closed.”

Voith’s BeltGenius product family is used for monitoring, benchmarking, and optimizing belt conveyors and conveyor systems. A key part of this is BeltGenius ERIC, which provides a digital twin of customer’s conveyor belts. The program processes sensor data in real time to calculate and compare the performance of different conveyor belts, and to point out possibilities for performance improvements.

Voith Turbo has been successfully running a prototype of Belt-Genius ERIC at a European mine for some time and, in September 2020, the project reached a milestone, by achieving all of its target metrics.

While 2020 was not without its challenges, Voith used the situation to further develop its remote training and support offering for customers in the mining space.

“The COVID-19 pandemic had impacts on our business, but due to our broad sectoral and geographical positioning as well as regional supply chains we have been able to endure the crisis relatively well,” Steck said. “We also saw some issues on the customer side e.g., delayed projects and limited travel activities, so we developed an online training.”

“Overall, in mining, we see a trend toward ‘man-less operations’ and therefore we need to collect and analyze data about each application. We see a gap for trained staff for maintenance and trouble shooting, so digital diagnostic capabilities are really important. The early detection of anomalies where operators can still intervene without unplanned downtime leads to higher productivity, and monitoring of safety factors can be used to optimize belt operation and avoid stoppages.

“Our vision is to become the ‘master of the drivetrain,’ so in addition to our core competence in hydrodynamics, we are developing further solutions to help them keep an eye on other conveyor system components.”

In line with this ambition, Voith Turbo is working hard on new digital solutions for mining applications. One example is the Turbo-
Guide online app.

“The TurboGuide development started after receiving feedback from a customer survey,” Steck explained. “We saw the following pain points from customer side: manuals were not available or too complicated to understand, technical data about optimal operation of constant-fill coupling T type were not available, complicated spare parts buying processes, fewer trained personnel for maintenance and trouble shooting.

“With the TurboGuide smartphone app, the customer can scan the QR-code on their couplings and receive information about the coupling directly, as well as the relevant manuals and further details concerning trouble-shooting, animations and a Voith service contact.

“Voith Turbo will continue developing digital products for the mining industry, especially for belt conveyor applications,” Steck said. “For sure, we will release further products to support our customers in terms of conveyor performance and energy efficiency, too.”

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