Designing Today’s Conveyor Systems for Tomorrow’s Needs

Miners expect the next generation of high-capacity conveyor systems to be longer, faster and more powerful. They’d also like them to be safer, quieter and energy efficient. Here’s what’s coming down the belt line from top suppliers.

By Russell A. Carter, Contributing Editor

Conveyors are consistently absent from inclusion in the “Ten technologies that will disrupt the mining industry” forecasts that consulting and market-survey companies seem to publish with increasing frequency. However, the fact that at least one mine’s bulk material transportation system can be seen from space – the conveyor from the inland Bou Craa phosphate mine in Morocco to a Mediterranean sea port 61 miles away, considered to be the world’s longest – confirms that conveyor technology remains a large and important link in the typical mine-to-market operational chain.

A lesser-known fact associated with that West Saharan conveyor system is that it’s not actually the conveyor hardware that can be seen from space; it’s the drifting residual dust released from the carried material that makes it visible to astronauts – a reminder that high-capacity conveyors can generate big problems involving dust control, proper belt loading and the need for monitoring and maintenance of vast stretches of conveyor hardware in often difficult-to-access areas.

A quick look at just one of the world’s largest mining companies offers a glimpse of the importance that reliable and efficient conveyors have in achieving planned production: Copper output at Rio Tinto’s Kennecott mine in Utah, USA dropped by 36% year-on-year between 2022 and 2023 due largely to motor problems on a conveyor linking the mine to a concentrator. Conveyor availability problems also hindered production at the Escondida copper mine in northern Chile, in which Rio has a 30% ownership interest. 

At the same time, the company has been taking steps in Australia to ensure the long overland conveyor systems in its Pilbara iron-ore mining operations perform at necessary levels. For example, last year Rio Tinto awarded two contracts worth a total of A$61 million for the supply of new conveyor pulleys and pulley rebuilds that will require a purpose-built facility in Karratha, Western Australia. It also gave Fenner Conveyors a major conveyor belt supply contract for one of the longest of Rio’s overland conveyors in the Pilbara region – the 23.8-km-long (15-mile) Western Turner Syncline conveyor system – one of three overland conveyors within the Western Turner Syncline mine which feeds ore into the Greater Tom Price mining operation.

Fenner will deliver 40 steel cord belts, each 595 m (1,900 ft) long and weighing just over 50 metric tons. These reel lengths, according to the company, are optimized to reduce the number of splices required to install the belt. The custom-made belts will feature Fenner’s premium cover compounds such as its Tuff As for superior cut and gouge resistance, and the newer PowerSaver 2.0 compound for low rolling resistance.

Comparing Environmental Cost

Mine project owners almost always have a choice of which bulk material haulage mode to employ at any given site. Truck haulage is generally acknowledged as having an advantage for operations in which the active mining areas might frequently open, close, shift or require ore blending from different zones; while conveyor systems are perceived to offer savings in labor and maintenance along with the elimination of emissions from direct usage of hydrocarbon fuels. 

In recent years, the closer attention given to a company’s carbon footprint and emissions performance now requires project owners to look at the conveyor vs. truck debate from a new angle: direct and indirect greenhouse gas (GHG) emissions – not just from operation of either haulage system, but also from the economic and environmental costs associated with manufacturing and installing a given system, along with the Scope 3 emissions related to infrastructure requirements necessary to allow system operation. A paper* presented at the 2023 SME Annual Conference addressed this issue, comparing five haulage options – diesel-electric haul trucks, battery-electric haul trucks, fuel cell haul trucks, the Railveyor (a light rail train propelled by stationary drive stations), and conveyors – in terms of GHG emissions.

Not surprisingly, the study showed that diesel-electric haul trucks are estimated to have the highest GHG emissions of all the haulage methods at 0.096 kg CO₂e/ton-km. Less apparent, perhaps, is their finding that the Scope 3 emissions associated with the infrastructure required for each method is the highest for conveyors, at 742 tons CO₂e/km of infrastructure. This high emissions factor, said the authors, comes from the amount of raw material and extensive installation work required by conveyor system infrastructure. 

These additional environmental concerns can have the effect of increasing the weight of system decision-making on a project owner contemplating a high-capacity overland conveyor system. Beumer Group, a major supplier in the conveyor systems sector, recently issued a paper addressing how mining companies can make their operations more sustainable to reduce their environmental footprints. Beumer said it relies on modern planning and layout tools to support operators at an early stage of the project and design an ideal conveying solution in collaboration with the customer.

Beumer claims to have installed the first overland conveyor with horizontal curves in the late 1960s. Since then, calculation methods and components such as idlers, belts and drives have undergone constant development, resulting in the implementation of increasingly efficient conveying systems for routes that are often complex. “We can exactly match our systems to the required conveying task and topography,” said Dr. Kilian Neubert, global head of mining at Beumer Group. 

The company points out that while raw materials are needed to produce almost all industrial and consumer goods, extracting them has far-reaching effects on the environment and society. 

“Mining companies need to build trust with the public,” Neubert explained, underscoring why operators need to integrate the issue of sustainability into all aspects of planning a mine and improve the environmental compatibility of the overall system by ensuring the efficient transport of ore and waste rock over longer distances. Optimized routing and the selection of suitable methods achieve these objectives, according to the company, which notes that no two conveying systems are alike, even if the primary task of transporting bulk material from A to B appears comparable.

In Beumer’s approach, the energy consumption of long, horizontal belt conveyors is primarily determined by the main resistance in the upper and return strand in stationary operating conditions. This resistance consists of the running resistance of the idlers, the indentation rolling resistance, and the flexing resistance of both the conveyed material and the belt as they run over the idlers. The forces required to overcome these resistances depend on various operational and design parameters; however, they can be determined using the ‘single resistance method.’ If components with low running resistances are used, such as belts with reduced indentation rolling resistance or optimized idlers, system calculations for newer systems show considerably lower tractive forces of the belt than those of just few years ago. This leads to lower energy costs, and smaller radii can also be selected for the horizontal curves due to the lower tractive forces of the conveyor belt.

The topography of the existing terrain also has a significant influence on the design of the conveying system. An in-depth analysis of various dynamic load cases and a thorough investigation of the technically feasible horizontal and vertical curve radii must be conducted to design the system in the most efficient and environmentally friendly way. This is especially true for longer and more difficult conveyor lines. Potential obstacles that must be considered during the planning phase include residential areas, roads, and rivers. “Today, we can design curved overland conveyors of up to 20 kilometers or longer without the need for a transfer tower,” said Neubert. Conveying capacities for these modern systems can be designed to handle more than 20,000 tons per hour.

“We use our Overland Layout Tool to ascertain the ideal layout for the system,” explained Neubert. “It generates a digital 3D model of the conveyor in the virtual landscape during project planning, more or less automatically.” The critical topography data can either be provided by customers, or drones are used to capture terrain data. “These 3D visualizations are also ideal for supporting mining companies in their public relations work,” said Neubert. “Important factors such as the necessary excavation work and the required steel structures for the conveyor can be evaluated and illustrated on this basis. This procedure considerably accelerates the project planning process and enables us to provide project-critical data to the customer at an early stage.” 

Beumer can also make a case for the use of pipe conveyors, a technology that the company began product development in the 1990s. In these systems, idlers form the belt into a tube that protects the material to be transported against external influences and the environment from dust. This conveying solution, according to the company, is ideally suited for fine bulk materials such as ore concentrates. Pipe conveyors also allow tighter curve radii and greater angles of inclination compared to conventional troughed belt conveyors.

But what if material with large particle sizes requires a larger pipe diameter? The rule of thumb is that the pipe diameter should be about three times the maximum particle size. To solve this problem, Beumer developed a U-shape conveyor. “This variant combines the advantages of a troughed belt conveyor with those of a pipe conveyor,” said Neubert. The idlers form the belt into a U-shape rather than a pipe. The U-shape conveyor enables tighter curve radii than a troughed belt conveyor and higher mass flows than a pipe conveyor and also protects the conveyed material from environmental influences and the environment from material loss and emissions.

Larger Systems, New Challenges

All high-capacity conveyor market trend indicators point to a future in which these systems will grow in size and power to meet the increasing production demands of the industry. New design concepts are expected to balance the benefits of higher throughput with corresponding requirements for energy efficiency, safety and system monitoring capabilities. Higher speeds and bigger belt loads pose challenges for mine operators in the areas of spillage and dust control, as well as for third-party suppliers of conveyor components such as motors, couplings, brakes, belt cleaners and idlers, rollers and pulleys. There will also be an increased range of opportunities for digital-solutions providers to assist in ensuring optimum design and performance through digital-twin modeling and analysis.

Although the conveyor sector isn’t known as a hotbed for radical product-development breakthroughs, promising new concepts occasionally emerge. One recent notable departure from conventional conveyor system design is the rail-running belt conveyor, which combines elements of light-gauge rail transport with the continuous nature of conventional conveyor systems. 

So, what is it? “In a nutshell,” Stefan Ebert, head of product line revamps at FLSmidth, explained, “the rail-running conveyor can be split into three segments: head and tail station, turnaround loop and conveyor route (between head and tail). The head and tail station basically remains as per a conventional conveyor arrangement using all the same components – in particular belt, pulleys, idlers, drives or take-up solutions.”

Developed by the University of Newcastle and thyssenkrupp – whose mining business was acquired by FLSmidth in 2022 – the system carries the belt on wheeled carts between the head and tail, with the belt as the tension member and the carts being carried along by their contact with the belt. Because the wheeled carts circulate past the head and tail ends of the conveyor, automated inspection eliminates the need for daily inspections along the length of the conveyor.

“However, due to the lower energy demand of rail running conveyors these have the potential to be designed remarkably smaller than with conventional conveyors at the same capacity. The full effect here can be drawn especially with new conveyors on the one hand, but on the other hand there is also the opportunity to upgrade to lower energy consumption or increase capacity while keeping the existing conventional head and tail stations in place.

“The turnaround loop is a solution to carry the carts from the carry-side of the conveyor back to the return-side (and vice-versa) and needs to be installed at both ends of the conveyor before the head and tail station. It can be designed, depending on the space available, horizontally (both symmetric or one-sided only) or even vertically.

“The conveyor route itself [comprises] new conveyor modules, equipped with railway tracks carrying the wheeled lightweight carts. The effects on friction via steel-on-steel instead of rubber-on-steel drive the savings in energy.” He explained that the system consists of five core elements in addition to the structural steelwork. These are the belt, railway track, wire rope, support carts and wheels. “The belt used is from conventional steel cord design and is equal to the belts on conventional conveyors. Existing belts with remaining service life can be used when upgrading a conveyor line to the rail-running technology.

“The railway tracks are supported by the module steel structures and carry the carts. The design is based on conventional railway technology. The wire rope connects the carts with each other to ensure correct spacing between the carts.

“The support carts are lightweight since they need to be ‘carried’ in addition to belt and material and have brackets to support and carry the belt. If required, additional measures and design elements will be added to the cart to mitigate de-railing risks. The wheels [are based] on proven railway/light rail technology and are designed for self-centering to minimize wear.”

Ebert told E&MJ earlier this year that two of these systems are planned for commissioning at a large African copper operation in late 2023 through 2024.

Aerial Inspection Takes Off

In one example of how a truly disruptive technology – aerial inspection – can help the mining industry bring the utilitarian nature of conveyor operations into the 21^st century, earlier this year Continental introduced the CONTI ConveyorInspect drone-based inspection system to allow operators to easily determine the condition of belts and idlers, quickly locate failing idlers and track changes in rotating components over time. Real-time reporting allows operators to better estimate their system’s component life and plan maintenance, leading to prevention of costly damage of conveyor system components and unscheduled down time.

The system can provide autonomous visual monitoring or can be guided by a drone pilot. During automated inspections, an infrared and RGB camera-equipped drone inspects both sides of the conveyor following a preprogrammed flight routine. Once the mission is completed, the drone returns to an autonomous charging station and uploads all the relevant visual data to the cloud. With the Drone Pilot inspection routine, a certified pilot controls the drone and collects data in dangerous or hard to reach places.

Once collected, visual data is uploaded to the cloud via the system’s portal, and the data is processed and analyzed by an Artificial Intelligence (AI) based data pipeline. The data analysis and reports can be reviewed via an app available on desktop and mobile platforms.

According to the supplier, Conveyor-Inspect has been engineered and built for the demanding conditions found in mining and extraction. The drone can operate in temperatures of -4°F to 113°F while inspecting conveyors at an average speed of 3 feet per second. With up to 40 minutes of continuous flight and a charging time of only 40 minutes, ConveyorInspect can operate over a maximum range of 3 miles (5 km) and at a maximum altitude of 400 ft (130 m). The drone is equipped with a 4K daylight camera and 640 x 512 thermal camera with a frame rate of 30 FPS.

Employing drone inspection technology even farther upstream in the mining chain can help prevent conveyor belt damage and system downtime from tramp metal such as lost drill rods and bits or broken ground-engaging tool (GET) components. SPH Engineering, a European drone technology developer, recently noted that Newcrest Mining has been using a drone equipped with a magnetometer to inspect tracts of active mining areas at its Telfer mine in Western Australia to identify high-probability indications of metal items for later pickup and disposal. The “GET detection drone” is a DJI M300 RTK equipped with SPH Engineering’s SkyHub onboard computer with True Terrain Following system and a SENSYS MagDrone R3 magnetometer, controlled by the company’s UgCS command software system.

Boosting Motor, Drive and Accessory Performance

To keep pace with future production needs, mine operators will look to electric motor, drive and power transmission manufacturers for integrated designs and broader ranges of output ratings along with better energy utilization performance and high reliability. Recent examples of technological advances in these areas include:

– ABB’s introduction of a “new generation” AMI 5800 NEMA induction motor, designed to offer better energy efficiency and reliability in demanding applications such as conveyors and crushers. Rated for a power output of up to 1,750 hp, the company said the AMI 5800 offers the capability for a high degree of modularity and customization to suit both new build and upgrade projects in a wide range of industries including chemical oil and gas, conventional power generation, mining and cement and metals.

According to ABB, the AMI 5800 motor is a true NEMA design that meets both electrical performance requirements and mechanical mounting standards. A key feature is a high-strength welded steel frame typically found only in motors with larger frame sizes. This lowers stress on the motor while mitigating vibrations and resonance to ensure reliable operation in harsh conditions with a design life of 25 years or 20,000 starts.

The company said an additional feature of the AMI 5800 is a shorter bearing-to-bearing span compared with previous models. This improves performance at high speeds and enables the motor to be used as a simple drop-in replacement to upgrade existing equipment.

Sam Patrick, ABB’s product manager–Large Motors & Generators, said about the new motor: “Its modular design in terms of cooling methods, bearings, shaft extensions and terminal boxes provides the flexibility to match the North American installed base. That makes the AMI 5800 ideally suited for both upgrading existing installations and next generation designs no matter how harsh the environment it will be operating in.”

According to the company, while the majority of regular AMI 5800 designs not only meet but exceed North American standards for energy efficiency, further customization will allow some models to operate above the IE4 equivalent level of energy efficiency while meeting NEMA electrical performance standards.

The new motor is configured for optimal airflow, meaning that it will run as cool as possible, whether in an open-air installation or enclosed with a cooler. The MICADUR insulation system makes the motor suitable for starting high inertia loads direct online (DOL) or with variable speed drives (VSDs).

– Atlas Energy Solutions selected Voith Turbo to supply a total of 21 TurboBelt 800 TPXL fill control fluid coupling drives and spares to power 42 miles of conveyor belt as part of Atlas Energy Solutions’ historic Dune Express project. ELIN Motoren, a Voith company, will also provide 21 customized low-noise electric motors for the project, including spares. Once in operation, the overland conveyor system will serve as a low-impact transport system, moving frac sand from Texas to New Mexico in the US and claiming a new world record for a single conveyor flight without a mid-belt drive with its 16.3-mile overall single flight length.

“As planned, the Dune Express is enormous,” said Roland Hoet, vice president-sales, HDC Voith Turbo Americas. “Conveyor CV-004, the last in the system, will be the world-record holder, and combined with the three conveyors earlier in the line, this 42-mile conveyor system will be the longest in North and South America, and the second longest in the world.”

Voith said the multimillion-dollar project required significant technical work, ultimately developing seven different drive package designs for the install. The drives needed to be designed to provide a specified acceleration time of 10 minutes for the conveyors. This extended start-up time was required to maintain belt tensions, especially along the lengthy horizontal curves for two of the system’s four belts. This start-up time is significantly longer than most large conveyors, which typically require 60 to 120 seconds.

“Voith’s new TurboBelt 800 TPXL fill control couplings are the latest design update to Voith’s TPXL family of fill control models,” said Hoet. “This new technology uses an advanced oil-filling control system which provides continuous fill-level control through a forward and reverse flow pump. It eliminates the On/Off function solenoid fill and drain valves of the previous fill control models.”

“The Atlas project is the largest Voith order in North America for complete drive packages,” said Hoet. “We are responsible for the main electric motors; the TurboBelt TPXL couplings; the gear reducers; the base frames; the connection couplings, both low speed and high speed; the air- to-oil coolers for the TurboBelt TPXL units; and the control system for the TurboBelts. This is an exciting project for Voith Turbo since it proves that hydrodynamic drive solutions can provide critical torque control for even the largest overland material handling conveyor systems.”

Playing it Safe

As conveyor systems become larger, longer and more powerful while the mining labor pool transitions from older, experienced workers to new and “green” employees, products that feature better worker safety, lower weight per unit and reduced maintenance can help “design the hazards out of the system” – a topic that conveyor equipment supplier Martin Engineering addressed recently, pointing out that conveyor system design should be “forward-thinking.”  This means exceeding compliance standards and enhancing operators’ ability to incorporate future upgrades cost-effectively by taking a modular approach. 

Martin warns that reflexively taking a traditional low-bid route for obtaining conveyor system engineering can lead to high-cost problems in the future. “Engineering safer conveyors is a long-term strategy. Although design absorbs less than 10% of the total budget of a project, Engineering / Procurement / Construction Management (EPCM) services can be as much a 15% of the installed cost of a major project, additional upfront engineering and applying a life cycle-cost methodology to the selection and purchase of conveyor components proves beneficial.  

“This method alleviates several workplace hazards, minimizes cleanup and maintenance, reduces unscheduled downtime and extends the life of the belt and the system.” Before the drafting phase, Martin recommends that designers should establish the goals of reducing injuries and exposure to hazards (dust, spillage, etc.); increase conveyor uptime and productivity; and seek more effective approaches to ongoing operating and maintenance challenges.  

One approach to improving worker safety that can also offer operational benefits is the use of lighter, less energy-hungry common components in appropriate applications. Durable rollers made with tough thermoplastics or composite materials now may equal or surpass the service life of traditional heavier metal versions and have the potential to reduce common maintenance-related worker injuries simply by being lighter and less difficult to handle. PROK and Rulmeca, two of the leading roller suppliers, have in recent years introduced lightweight roller technology for mining-class conveyor applications. 

Rulmeca said its Composite Roller features a glass-filled, high-density polyethylene tube. According to the supplier, the polymer material is sturdy and the wall thickness of the tube provides high load-carrying capacity and impact resistance. The material is resistant to abrasion and corrosion caused by environmental factors or the conveyed material itself, leading to extended service life even in harsh operating conditions.

When fitted with an FRAS labyrinth seal and stationary stone guard, the roller’s sealing mechanism both inhibits the ingress of dust or moisture into the bearing area and resists buildup of static electricity, according to the company. The guard prevents the roller from seizing if rocks get jammed and provides increased protection for seal and bearings. 

PROK’s newest high-density polyethylene (HDPE) roller was introduced in mid-2021, described by the company as being lighter, more durable and designed for high-speed, large-tonnage applications where reliability is crucial. The company said it pioneered the use of lightweight HDPE material in conveyor rollers over 10 years ago while searching for a solution that would not damage the conveyor belt in the event of failure and would reduce the risk of manual handling injuries when rollers were being installed or changed out.

The HDPE rollers include a premium seal arrangement with low friction properties to ensure low break away mass and run resistance during operation. They come in a range of sizes and feature visual wear indicator technology.

More recently, PROK introduced its Belt Lifter, a device designed to reduce the risk of worker back injuries resulting from manually lifting conveyor belts for roller replacement. Weighing less than 25 kg (55 lb), the Belt Lifter is claimed to be easy to carry and operate by one person. It is designed on standard PROK conveyor idler mounting dimensions and, according to the company, is suitable for use on 95% of all conveyor applications.

The lifter, according to the company, offers features that can improve safety and simplify the process of changing conveyor rollers: these include quick setup and operation, with a power drive that reduces downtime required to change out rollers. The device provides a safe mechanical aid that reduces the risk of injury, allowing idler frames to be replaced as easily as the rollers. Additionally, the Belt Lifter can be quickly collapsed and relocated, reducing downtime. The product range also includes a heavy-duty option suitable for larger belt widths.