This two-section overland trough conveyor system is designed by TAKRAF to accommodate hilly terrain, villages, rivers and forests, delivering 1,500 mt/h of crushed bauxite ore to Utkal Alumina’s plant 11.5 miles away in Orissa, India.

Miners can choose from an array of system configurations, products and services that help keep the ore moving by detecting and analyzing – or just avoiding – problems that cause unplanned stoppages

By Russell A. Carter, Contributing Editor

Think “conveyor,” and a perception of continual motion comes to mind. That’s probably why it’s always startling to see a main conveyor offline during a production shift, because that means the stoppage is most likely unscheduled — and therefore expensive. The prospect of unplanned belt downtime is high on the list of concerns that keep production and maintenance managers on edge — and consequently is a major driving force behind the constant flow of new and improved conveyor designs, components and services available from OEMs and aftermarket suppliers.

Mine conveyor systems are getting more complex and powerful to meet challenges that range from extracting higher volumes of lower-grade ore on the surface, or going deeper underground to reach new resources; to the need to transition systems from diesel to electric power as part of industry-wide decarbonization initiatives. In order to meet these growing issues, most recent large-scale conveyor projects employ a variety of innovative design features and technologies that often mesh with the industry’s shift toward digitalization, energy conservation, fewer transfer stations, and reduced worker presence on site.

Rise of Remote Inspection

Regardless of age, length or complexity, conveyors running in the harsh conditions typical of mine sites need regular inspection and upkeep. Traditionally, this has been done by workers “walking the belt,” and while there’s no substitute for an experienced technician providing eyes-on inspection in the field, there are drawbacks, such as the hours needed for those walks when that valuable employee’s time could be better spent elsewhere, the hazards of accessing and working around dusty, powerful equipment in motion, and the variability of human perception — what one worker sees or hears might be treated quite differently by another, or completely missed.

The viability of remote inspection has grown apace with the availability and continuing refinement of monitoring, scanning, and data acquisition platforms and products. The variety of solutions available to meet customers’ monitoring needs vary from basic fiber-linked sensor arrays on rollers and pulleys to comprehensive packages that collect near- or real-time data for detection of potential or actual system problems.

As an example of the latter, ABB launched its Ability Condition Monitoring solution for belts earlier this year, describing it as an advanced digital service that enables mine operators to track speed, misalignment, damage, thickness and wear, slippage and temperature of conveyor belts in real time, and therefore anticipate maintenance, avoid unplanned downtime, and improve belt reliability and lifetime.

According to the company, Ability Condition Monitoring for belts offers a complete overview of the assets’ condition through continuous monitoring of belt health, generating alarms and warnings in the event of deterioration. By moving from preventative to predictive maintenance, it enables operators to avoid costly failures that can occur between physical inspections and personnel can be removed from dangerous areas.

The technology is based on sensors installed in strategic points of the conveyor belt equipment and is specifically designed to withstand harsh environments while monitoring asset health and condition according to ABB, which also noted that the system provides easy access to informative dashboards. Fault trend analysis, event alarms, data logs and reports can be monitored for single or multiple conveyors and by remote connection, SMS text message and email.

“Real-time monitoring of the actual belt performance prompts the necessary corrective actions ahead of failure or further and more costly damage,” said Eduardo Botelho, global material handling service product manager, ABB. “With equipment condition continuously assessed, operators can plan necessary maintenance only when certain indicators give the signal that the equipment is deteriorating, and the probability of failure is increasing. It will consistently catch misalignment or speed issues online, long before failure, and pre-empt issues such as falling material, energy waste, excessive belt wear, rupture or fire.”

According to ABB, Ability Condition Monitoring for belts can be a stand-alone option or integrated into any control system, being interoperable with existing maintenance tools and infrastructure. KPIs can be customized to meet customer requirements.

Continental AG introduced its own monitoring system recently as well, offering a combination of visual and acoustic inspection capabilities along with data-assisted planning of maintenance intervals.

The company pointed out that about 30% of the operational faults encountered with belt conveyors are attributable to idler problems, and even a medium-sized overland conveyor can have many thousands of idlers, making it almost impossible to consistently identify idler-related problems in a timely manner. Continental’s solution begins with aerial inspection of open sections using a drone equipped with infrared and RGB cameras that monitors both sides of the belt conveyor. After the drone completes a survey flight, it returns to an autonomous charging station and uploads the data it collected as it recharges. The image data is processed with the aid of an AI-assisted (artificial intelligence) algorithm and analyzed for any detected idler defects.

Monitoring in covered sections or underground conveyors is carried out using fixed microphones installed every 20-25 m that capture frequency variations in the idlers. Audio recording occurs twice daily, and data is uploaded to the cloud. Indications of a damaged idler are then investigated using an AI-based algorithm.

“Conventional and often manual inspection methods can be very time-consuming, imprecise or even dangerous for service technicians because of the belt length or local circumstances such as underground routing and enclosed sections,” explained Clemens Panzer, a member of the interdisciplinary team set up for this project. “Documentation is also often performed manually, with reports having to be manually input subsequently into the relevant datasets. Maintenance intervals also frequently follow a fixed rotational principle, meaning that measures required on short notice to avoid or prevent conveyor failures cannot be carried out in a timely manner. Sensor-based inspection, by contrast, permits data-assisted remote monitoring of system condition, with the result that potential damage can be detected at an early stage and avoided.”

Continental said its system has been successfully tested in field trials and additional pilot projects with potentially interested parties are planned. The product is scheduled to be operational in 2021.

Strata Worldwide, a Georgia, U.S.-based provider of mining technology products, recently signed a partnership agreement with AVA Risk Group’s Future Fibre Technologies subsidiary to distribute that company’s FFT Aura IQ conveyor health monitoring system. Cloud-based Aura IQ, according to Strata, allows alerts and reports from conveyor assets located anywhere in the world to be accessible on any Internet-enabled device in near real-time, with no specialist software or equipment.

Aura IQ transmits a series of short, laser pulses through a single fiber-optic cable that can be retrofitted along the length of a conveyor. Acoustic disturbances from the conveyor system cause microscopic changes in the backscattered laser light that is then categorized into known parameters.  Data is simultaneously gathered from every meter of the conveyor and processed to pre-emptively alert operators, either on or off-site in operational hubs or control rooms, to potential failures before they happen. This includes detecting a broken ball or a cracked cage in a ball race, observing and tracking idler bearings as they progressively wear, and predicting potential bearing seizures and prioritizing roller replacements at the next maintenance shut down.

FFT said Aura IQ, developed in partnership with Australian research organization Mining3, has been tested internationally in both surface and underground operations. As a result of these tests, a new version of the conveyor condition-monitoring algorithm for acoustic sensing has been implemented. Other improvements include the ability to monitor conveyor line stands with different idler configurations as well as remove spurious noise frequencies.

ABB Ability Condition Monitoring for belts provides access to dashboards that allow fault trend analysis, event alarms, data logs and reports to be monitored for single or multiple conveyors and by remote connection, SMS text message and email.

Overcoming Old Obstacles

Not all conveyor design advances are targeted toward future tech demands, however. As mature mines look to upgrade their material-handling capabilities, they and their contractors often have to overcome conveyor-system layout problems posed by buildings, landforms, communities and civil works that may have evolved over decades of mine operations. In other cases, the development of remote-but-related mining and processing sites over the course of years leads to the necessity of linking those sites via conveyor systems over terrain that’s not highly amenable to construction and maintenance access. The challenge has been, as always, to provide optimal value to the customer at a justifiable price and with minimal site and operational disruption.

Some fairly recent, large-scale conveyor projects are good examples. When TAKRAF and project partner ABB announced in 2020 they had successfully commissioned the industry’s most powerful gearless conveyor drive system as part of the conversion to underground mining at Codelco’s Chuquicamata mine in northern Chile, they pointed out a number of “firsts” the project embodied including a total 58 MW of drive power for the system and the use of high-strength ST10000 conveyor belting on the system’s long-haul uphill conveyor flights. Dr.-Ing. Mario Dilefeld, head of belt conveyor systems at TAKRAF, also noted that system design had to take into account “…the landscape surrounding the processing plants has been shaped by over 100 years of mining at Chuquicamata. In addition to the various processing systems, waste heaps, train tracks, roads, pipelines, and buildings scar the landscape.” Any new system, explained Dilefeld, had to take into consideration this landscape for its entire length from the end of the underground tunnel to the processing plant more than 5 kilometers (km) away.

In order to accommodate the existing conditions, Dilefeld explained, TAKRAF designed a continuous single-flight conveyor that stretched 5,330 m between the loading and discharge points, with a difference in height of 287 m; horizontal curves with tight radii (1,600 m to 2,300 m) on more than 60% of the conveyor length; and approximately 50% of the conveyor length had to be mounted on elevated structures and with support intervals of up to 96 m.

A few years earlier, TAKRAF India successfully completed a 19-km overland conveyor system for the greenfield Utkal Alumina project in India’s Orissa state. The project called for an overland conveyor system to transport bauxite from the mines to a new 4.5-million-metric-ton-per-year alumina plant. The layout, according to the company, included the longest single-flight conveyor system to be installed to date within India.

The system’s two conveyors traverse a highly undulating and complex terrain. Dropping in total by 250 m over its length from loading point to discharge, the system encounters 11 streams and a river, a forest stretch nearly 470 m long, a high-voltage line crossing, 37 road crossings, a paddy field adjacent to the plant boundary that extends approximately 2.5 km, eight hills and several villages. As a result of the topography and due to the conveyor length, the conveyors were designed with head and tail drives, and multiple tight compound horizontal and vertical curves. In total, the conveyor system features 10 right-hand curves, four left-hand curves and horizontal curve radii of 2,500 m across all locations but one: a critical zone on the shorter conveyor where the horizontal curve is 1,800 m. The overall system features 403 straight sections, 154 right-hand curves and 61 left-hand curves, with a maximum gallery length/support interval of 49.5 m and standard gantry length of 27 m.

At about the same time that the Utkal project was under way, Chinese steelmaker Shandong Steel was looking for an economical solution for transporting large quantities of iron ore from the port of Langshan to its plant. The company had previously relied on an existing pipe conveyor, but the capacity of that system was no longer sufficient to handle the needed volume. The question for Shandong Steel was: Should the plant use a well-developed existing railway and road network or invest in a conveyor system solution to deliver the ore? The steel company’s engineering contractor, Shandong Harbour Engineering, turned to the Beumer Group for input, as Beumer engineers were already familiar with the existing system. Subsequently, the contractor awarded Beumer the project for installation of additional pipe conveyors. Over the course of eight months, Beumer implemented a conveyor system roughly 6.6-km long capable of delivering 5,500 mt/h of ore.

“Of course, we had to prove that this investment was worthwhile,” said Zhengwei Zhang, project manager at Beumer Machinery (Shanghai). “In advance, we performed an economic evaluation.” This included a feasibility study, an investment calculation, the project schedule and a cost-benefit analysis. Different variables are required to compare the costs of pipe conveyors with those of trucks or trains. For example, the transport costs per ton, the material volume that needs to be moved within a set period of time, and also the specific investment costs and the tax depreciation plan.

Beumer said its pipe conveyor technology enables horizontal and vertical curves, an important consideration in this particular project because the route encounters roads, residential areas and rivers. According to the company, depending on the characteristics of the conveyed material as well as the system’s geometry, it is possible to implement vertical curves with angles of inclination up to 30 degrees and horizontal curves with a deflection angle of up to 90 degrees. This ability to navigate curves reduces the number of supports and replaces transfer towers, which results in substantial cost savings for the customer. The closed design of this type of system also protects the environment from spillage and excessive dust.

3 Shandong Pipe Conveyor

The Beumer-designed pipe conveyor linking Shandong Steel’s steel plant with the nearby port of Langshan in eastern China offers the advantages of flexible layout options along with elimination of spillage and dust in populated areas along its route.

Improvements in Iron

Algorithms are the computerized thought processes of “smart mining” technology, using knowledge derived through machine learning principles to categorize, recommend, direct or deny actions based on big-data analysis. In their most useful forms, algorithms can expedite decision-making for complex functions that are simply too massive, tedious or variable for humans to consistently cope with.

A case in point is BHP’s material handling network at Port Hedland, Western Australia. It’s highly complex, comprising five car dumpers, eight stackers, five reclaimers, three lump rescreening plants and eight ship loaders, all connected by about 100 conveyor routes. Selecting the fastest route to send the right material to the right ship is a challenge and BHP turned to technology for a solution.

The company said it now uses algorithms to identify high- and low-performing car dumper routes, then select those that reduce dump times and positively impact vessel lineup. It has measured an uplift in outflow capacity of 1.4 million metric tons per year (mt/y) with very limited capital investment.

However, not every aspect of conveyor operations lends itself to becoming electronically distilled into a neat algorithm. There’s ample opportunity for physical improvements in performance and reliability of “the iron” — pulleys, rolls and frames that are generally the first victims of abrasion, corrosion and other common threats to conveyor system health.

As Iowa, USA-based Precision Pulley & Idler (PPI) noted, extending pulley life in abrasive applications is an ongoing challenge in the conveying industry. At MINExpo, the company exhibited its new ContinuWing technology, which it said incorporates superior wear resistance into both herringbone and conventional wing pulley models by utilizing chromium carbide instead of the mild steel or AR alloys generally used on the face of a wing.  This improvement, it claimed, can significantly extend the service life of pulleys.

With a Rockwell hardness of 58-66 HRC compared to AR400’s 43 HRC hardness rating, chromium carbide is definitely harder, but hardness is not the sole factor that allows this product to excel, according to PPI — it’s the austenitic matrix structure that gives it excellent sliding wear resistance. The surface contains numerous hairline cracks, which are a natural stress-relieving characteristic.

PPI also announced that, through a partnership with the Australian company Vayeron, which specializes in IIoT hardware and data analysis systems, its idler rolls can be equipped with Vayeron Smart-Idler technology capable of conducting on-board vibration, shell wear and carryback buildup analysis, and measuring bearing temperatures, idler RPM, rotation count and belt skipping events.

Smart-Idler components include a rotor that generates rotational energy for the idler, a stator that is shaft-mounted to harvest the rotational energy and also contains the on-board processing capabilities, and an antenna cover ensuring the smart idler antenna is not damaged in the field. The idler roll data is collected and sent to a gateway that interfaces to a PLC or cloud-based server via cell tower Wi-Fi or internet over ethernet connection.

PROK, a conveyor component manufacturer owned by NEPEAN, another Australian company, introduced a new high-density polyethylene (HDPE) roller it claimed is lighter, more durable and avoids secondary conveyor damage in the event of a failure.

PROK’s global product and engineering manager, Ray Anderson, said the new roller was specifically designed for high speed and large tonnage applications where reliability was crucial. “If a traditional steel roller breaks, it can damage the conveyor belt and the whole conveyor system can go offline, so the mining industry has been steadily moving toward lighter, more durable rollers made of advanced composite materials.”

PROK 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 company said the HDPE rollers are suitable for corrosive environments and include a premium seal arrangement. The rollers come in a range of sizes and feature visual wear indicator technology.

PPI’s ContinuWing winged pulley models feature chromium carbide wingtip protection for increased wear resistance and longer service life.

Drives: Smaller Footprint, Increased Options

Bosch Rexroth displayed its new generation of Hagglunds hydraulic motors at MINExpo, including the very compact Atom series and the wide-ranging CB direct-drive product line (See Equipment Gallery, p. 60). The company also highlighted its CMp condition monitoring program, comprising a connectivity tool and ODiN analytics package that can monitor the health of new and existing Hagglunds systems. When indicated by monitoring and analysis, factory-trained and certified service technicians will provide support in accordance with predetermined service levels.

ZF Group presented innovations including a next-generation Redulus4F industrial gearbox series and advanced serviceability options based on its ProVID condition monitoring system, which features an extended global support network designed to provide rapid detection and maintenance.

The new Redulus4F industrial gearboxes feature what the company described as a flexible, compact design capable of creating more than 2,000 gearbox combinations, while delivering extended load capacity and advanced serviceability — all in one package. An innovative Redulus4F “construction kit” includes 20 gearbox sizes designed to support up to a 40% increase in torque and covers a torque range of 99 kNm up to 5800 kNm, resulting in higher load capacity and optimal machine performance. The company said the unique design of this compact gearbox features a smaller outer diameter, less weight and requires less space, enabling a simplified installation process and reduced costs.

Dana announced upgrades to the company’s line of Brevini helical and bevel helical gearboxes used in mining and bulk material handling applications. The upgrades include three new monoblock models to more precisely address torque demands, as well as series-wide design enhancements that improve power density. Offering nominal output torques up to 1,000 kNm, the company said they have been redesigned with superior torque density to deliver more power from a smaller package, which improves efficiency, reduces weight, and minimizes lubrication requirements.

Dana said its Brevini helical and bevel helical gearboxes are engineered with low-temperature housings and special seals that support operations in extreme environments. They can be customized with a wide range of gear configurations, ratios, and input and output shafts. The new gearboxes will be available starting in early 2022.