Tag Archives: Martin Engineering

Martin Engineering on resolving bulk material handling issues with flow aids

In order to achieve controlled and consistent flow on conveyors handling large volumes of bulk material, transfer chutes and vessels must be designed not just to accommodate – but to actually facilitate – the flow of the cargo they will be handling.

Unfortunately, because so many conditions can hamper effective cargo flow, engineering a conveyor and chutework that would handle every material situation is virtually impossible.

Even modest changes in moisture content can cause adhesion to chute or vessel walls or agglomeration at low temperatures, especially if the belt is stagnant for any period of time. Even during continuous operation, a bulk material can become compressed, and physical properties often change due to natural variations in the source deposits, suppliers or specifications, or if the material has been in storage. If left to build up, material can encapsulate belt cleaners and deposit harmful carry-back onto the return side, fouling idlers and pulleys, according to Martin Engineering. At worst, systems can become completely blocked by relatively small (and common) changes. To overcome these issues, a variety of devices collectively known as flow aids can be employed.

What Are Flow Aids?

As the term implies, flow aids are components or systems installed to promote the transport of materials through a chute or vessel, controlling dust and spillage. Flow aids come in a variety of forms, including rotary and linear vibrators, high- and low-pressure air cannons and aeration devices, as well as low-friction linings and special chute designs to promote the efficient flow of bulk materials. These modular systems can be combined in any number of ways to complement one another and improve performance. The components can be used for virtually any bulk material or environment, including hazardous duty and temperature extremes. One of the primary advantages is that an operation can obtain a level of control over the material flow that is not possible any other way.

When employing flow aids, it is critical that the chute and support components are sound and the flow aid be properly sized and mounted, because the operation of these devices can create potentially damaging stress on the structure, the company says. A properly designed and maintained chute will not be damaged by the addition of correctly sized and mounted flow aids.

It is also important that any flow aid device be used only when discharges are open and material can flow as intended. The best practice is to use flow aids as a preventive solution to be controlled by timers or sensors to avoid material build-up, rather than waiting until material accumulates and restricts the flow. Using flow aid devices in a preventive mode improves safety and saves energy, since flow aids can be programmed to run only as needed to control buildup and clogging.

Air cannons

One solution for managing material accumulation in chutes and vessels is the low-pressure air cannon, originally developed and patented by Martin Engineering in 1974. Also known as an “air blaster”, it uses a plant’s compressed air to deliver an abrupt discharge to dislodge the buildup. Cannons can be mounted on metallic, concrete, wood or rubber surfaces. The basic components include an air reservoir, fast-acting valve with trigger mechanism and a nozzle to distribute the air in the desired pattern to most effectively clear the accumulation.

The device performs work when compressed air (or some other inert gas) in the tank is suddenly released by the valve and directed through an engineered nozzle, which is strategically positioned in the chute, tower, duct, cyclone or other location. Often installed in a series and precisely sequenced for maximum effect, the network can be timed to best suit individual process conditions or material characteristics. The air blasts help break down material accumulations and clear blocked pathways, allowing solids and/or gases to resume normal flow. In order to customize the air cannon installation to the service environment, specific air blast characteristics can be achieved by manipulating the operating pressure, tank volume, valve design and nozzle shape.

In the past, when material accumulation problems became an issue, processors would have to either limp along until the next scheduled shutdown or endure expensive downtime to install an air cannon network. That could cost a business hundreds of thousands of dollars per day in lost production. Many designers proactively include the mountings in new designs so that future retrofit can be done without hot work permits or extended downtime. A new technology has even been developed for installing air cannons in high-temperature applications without a processing shutdown, allowing specially-trained technicians to mount the units on furnaces, preheaters, clinker coolers and in other high-temperature locations while production continues uninterrupted.

Engineered vibration

The age-old solution for breaking loose blockages and removing accumulations from chutes and storage vessels was to pound the outside of the walls with a hammer or other heavy object. However, the more the walls are pounded, the worse the situation becomes, as the bumps and ridges left in the wall from the hammer strikes will form ledges that provide a place for additional material accumulations to start.

A better solution is the use of engineered vibration, which supplies energy precisely where needed to reduce friction and break up a bulk material to keep it moving to the discharge opening, without damaging the chute or vessel. The technology is often found on conveyor loading and discharge chutes, but can also be applied to other process and storage vessels, including silos, bins, hoppers, bunkers, screens, feeders, cyclones and heat exchangers.

There is another innovative solution that prevents carry-back from sticking to the rear slope of a discharge chute. The live bottom dribble chute uses material disruption to reduce friction and cause tacky sludge and fines to slide down the chute wall and back into the main discharge flow. By addressing these issues, operators can experience a reduction in maintenance hours, equipment replacement and downtime, lowering the overall cost of operation.

Flow aid devices deliver force through the chute or vessel and into the bulk material. Over time, components will wear, or even break, under normal conditions. Most of these devices can be rebuilt to extend their useful life. Because clearances and fits are critical to proper operation, it’s recommended that flow aid devices be rebuilt and repaired by the manufacturer, or that the manufacturer specifically train plant maintenance personnel to properly refurbish the equipment.

This article was provided to International Mining by Martin Engineering

Martin Engineering expands conveyor training scope with LMS integration

Martin Engineering has added new online conveyor training content specifically designed to integrate with Learning Management Systems (LMSs) so users can assign, monitor and certify progress of all participants during its courses.

The new offering from Martin Engineering includes eight self-paced modules that address methods to identify, understand and correct common bulk conveying issues to improve safety on powerful and potentially dangerous systems, while complying with regulations, maximising productivity and achieving the lowest operating costs.

“Online conveyor training is delivering critical knowledge to companies around the world, and that’s never been more important than in these pandemic-restricted times,” Training Manager, Jerad Heitzler, said. “But, even as the popularity of these programs continues to rise, larger firms face challenges integrating the content into their LMSs so they can ensure thorough and convenient training for all employees – at all levels – across multiple sites. These modules create a verifiable record of employee training, so customers can track and confirm the participation of individuals company-wide.”

Organised into 90-120 minute segments, the virtual classes cover topics such as best practices for safety, fugitive material control and belt tracking.

With the training modules easily accessible and conveniently located in company-wide LMSs, the new Martin content gives customers complete control over scheduling and tracking, the company says.

“This is the type of training that everyone should have, and companies no longer need to rely on an outside vendor to schedule individual or group sessions,” Heitzler continued. “It delivers an in-depth and consistent understanding of conveyors and their hazards, ensuring that personnel at all levels can work safely and efficiently around these powerful systems.”

Martin Engineering has been providing training for much of its 75-plus year history, helping customers better control bulk material flows while reducing the risks to personnel. Designed to maximise employee engagement, the modules deliver topic-specific, non-commercial content that can be put to immediate use, and the new format allows even the most remote locations to take advantage, the company says.

The eight modules cover essential subjects that include an introduction to the concept of total material control, with content on transfer points, belting and splices, as well as belt cleaning, alignment and dust management.

“This system is created using a SCORM 1.2-compliant format, so it will integrate seamlessly with most existing LMSs,” Heitzler added.

SCORM is a widely used set of technical standards that provides the communication method and data models that allow eLearning content and LMSs to work together. All eight modules are currently available in English, Spanish and Portuguese, and can be provided in a variety of formats to meet the requirements of specific customers and their LMSs.

“Seven of the eight modules have a test at the end, requiring a minimum score of 70% to move on to the next module,” Heitzler said. “SCORM allows the content to interact with the LMS and leverage any features that a customer’s system has, which could include tracking the progress of each learner, providing reports or issuing certificates of completion.”

He concluded: “With this new effort in place, Martin has taken another step forward in global conveyor training. We’ve emerged as an LMS content provider to deliver greater flexibility and control over employee learning, helping customers attain the highest levels of efficiency and safety.”

Conveyor belt cleaner tension: the keys to optimal performance

While it is clear there is no single or ideal solution for conveyor belt cleaning and tensioner selection, Todd Swinderman* of Martin Engineering thinks companies need to put the due diligence hours in to make the optimal choice.

Conveyor belt cleaners have evolved over the last 50 years from mostly home-made designs to a wide variety of engineered solutions to suit virtually every application. The expectations have changed over time as the relationship between health, safety and productivity and clean belts have become more widely accepted. As development continues, a single solution to the problem of belt cleaning and tensioner design is unlikely to be found due to the numerous variables and conditions that affect belt cleaner effectiveness.

General requirements

A discussion about belt cleaner tensioners must include the basic approaches to belt cleaning, as the most effective approach is achieved through a combination of cleaner and tensioner designs. Industry has gravitated toward mechanical cleaners and tensioners because they are simple and economical. The most common mechanical belt cleaner designs present a blade or brush at various angles to the belt. Depending on the cleaner type and materials of construction, they can approach the belt at either a positive, negative or zero rake (Figure 1).

Figure 1 – Blade style cleaning angles

Regardless of the basic cleaning approach, maintaining the optimum range of contact pressure will result in the best balance between cleaning performance, cleaning element wear, belt wear and power requirements. CEMA Standard 576, ‘Classification of Applications for Bulk Material Conveyors Belt Cleaning’, provides a performance-based classification system for use in specifying belt cleaners.

Basic approaches to tensioning

There are two basic approaches to applying tension to the belt cleaner: linear and rotary (Figure 2). The blade’s angle of approach to the belt often dictates whether a linear or rotary tensioner is applied. The stored energy that creates the tensioning force most often comes from gravity, springs or actuators. CEMA defines the cleaning positions as Primary, Secondary and Tertiary (Figure 3). Most belt cleaners mounted in the primary position utilise a rotary style tensioner, while most belt cleaners mounted in the secondary or tertiary positions use linear style tensioners.

Figure 2 – Basic tensioning approaches
Figure 3 – CEMA-defined cleaning positions

Linear tensioners

Linear tensioners are most often applied where the compensation for wear is required in small increments, such as with hard metal-tipped cleaners located in the secondary cleaning position or with brush cleaners. The basic tensioner design approach is typically a carriage that constrains the support frame but allows linear movement along a guide or guides roughly perpendicular to the belt surface, with the support frame and blade design providing the cleaning angle. Some designs incorporate a relief ability for impact by splices or belt defects.

The advantages of linear tensioners include: 1) simple in design; 2) can be engineered to one setting for full blade wear; 3) access windows are easily incorporated within the mounting footprint; 4) can accommodate actuator deflection scales for accurate adjustment of cleaning pressure and; 5) delivers the ability to adjust for uneven mounting positions or asymmetrical blade wear.

The disadvantages of linear tensioners include: 1) the tensioner footprint can be large, restricting options for ideal belt cleaner installation; 2) there must be access to the far side for adjustment; 3) the guide mechanisms are subject to fouling from dust and corrosion; and 4) changing from bottom adjustment to top adjustment or providing for adjustment from one side complicates the tensioner design.

Rotary tensioners

Rotary tensioners utilising an actuator are principally designed using a lever arm or an elastomeric element that is concentric with the belt cleaner support shaft. They apply a blade-to-belt contact surface determined by the actuating force and linkage geometry. The energy source delivers a force to the lever arm which rotates the shaft and forces the belt cleaner blade(s) against the belt surface. Rotary designs tend to be compact and, in most cases, the actuator(s) can be mounted at any orientation, which provides options for installing the belt cleaner in the optimum position.

Counterweight tensioner

At one time the most common rotary tensioner was a counterweighted lever arm, with its position adjusted to apply the design cleaning force to a blade or blades that contact the belt. A counterweight can be mounted on one end of the shaft or both. Usually, the initial installation would have the arm angle set so that at the midpoint of the blade wear the arm would be horizontal, thus roughly averaging the design cleaning force over the life of the blade (Figure 4).

Figure 4 – Typical counterweight tensioner

The primary advantage of the counterweight design is that it is self-adjusting by gravity. The disadvantages of the counterweight design are: 1) the lack of damping which allows the blade and therefore the weight to bounce when struck by a splice, strongly adhered material, like ice or a defect in the belt. The unexpected movement of the counterweight can represent a safety hazard and uncontrolled bouncing can result in belt top cover damage; 2) the counterweight tensioner takes a significant amount of space; and 3) if the counterweight arm cannot be mounted horizontally there is a reduction in the force applied to the blade, because the effective lever arm is shortened.

Rotary lever arm and actuator tensioners

Rotary adjustment of the belt cleaning blade can be accomplished in several ways. The support frame is almost always in a fixed location but free to rotate. The required tensioning forces can be applied by many types of actuators, such as: springs, fluid cylinders, electric actuators or from torque stored in an elastomeric element. Rotary tensioners are often used with elastomeric blades, where the change in blade height and thickness as it wears is significant (Figure 5).

Figure 5 – Rotary tensioner types

The advantages of rotary tensioners are: 1) a compact design; 2) a single tensioner mounted on one side of the conveyor can often be used for a range of blade styles and belt widths; 3) they can be designed to minimise the number of times the tensioner has to be adjusted during the life of the blade; and 4) many types of actuators can be used.

The disadvantages of rotary tensioners are: 1) there can be a safety hazard if the support frame is mounted too far from the pulley and the cleaner pulls through; 2) the mounting location of the axis of rotation is critical for proper blade cleaning angle; 3) the constant force output by some actuators can result in a wide variance in cleaning pressure and blade life over time; and 4) when a tensioner is required on both ends of the support frame, it is often difficult to access the drive side of the conveyor for mounting and adjustment.

Other factors

The importance of proper installation should not be overlooked for the proper performance of the belt cleaner. Slight variations in the location of the support frame relative to the belt can cause significant issues with the effectiveness of the blades and can result in support frame bending. Most manufacturers provide detailed instructions for the location of the support frames and tensioners, which must be followed for optimal function.

To be effective, belt cleaners should be frequently inspected and maintained. In practice, the design of the conveyor structure and location of the drive and other equipment makes service difficult. Consideration in the design stage for easy access and ergonomic location of the cleaners for inspection and service will pay dividends in reducing carryback, maintenance time and potential exposure to injuries.

To maximise blade effectiveness and minimise rapid wear, the recommended adjustment protocols should be followed. Studies have shown that there is a critical cleaning pressure range for various types of cleaners and blade types. These studies demonstrate that over-tensioning the belt cleaner does not necessarily improve the cleaning effect, but often results in increased belt and blade wear as well as higher power consumption.

The future of cleaner tensioning

As technology continues to advance, suppliers are beginning to integrate an increasing level of functionality in belt cleaner designs. One such innovation is a belt cleaner position indicator that can monitor the blade and estimate remaining service life based on the current hourly wear rate. Able to retrofit directly to existing mainframes, the device is capable of sending a notification to maintenance personnel or service contractors when a cleaner requires re-tensioning or replacement.

This capability brings a number of benefits. Inspection and service time is reduced, as maintenance personnel no longer need to physically view the cleaner to determine the tension or wear status. It also reduces the time workers need to spend near the moving conveyor, helping to minimise the potential for accidents. By relying on data – not human judgement – to maintain the appropriate tension for optimal cleaning performance and monitor blade wear, the indicator maximises service life and reports with certainty when a blade is nearing the end of its useful life, delivering a greater return on cleaner investment. Replacement orders can be scheduled for just-in-time delivery, reducing the need to stock parts inventory, and installation can be scheduled for planned downtime instead of on an emergency basis.

Taking the technology a step further is another patent-pending device that combines the position indicator with an automated tensioner. This novel powered assembly incorporates sensors that constantly monitor blade pressure and adjust its position to maintain optimal cleaning tension. Maintenance personnel no longer need to visit each cleaner and manually re-tension. Instead, the tasks are performed automatically, reducing maintenance time while maximising the usable area of every cleaner. Analytics provide an unprecedented view and understanding of belt cleaner performance, with real-time data available remotely via a specially designed app.

Automated tensioner

Conclusion

While manufacturers continue to improve belt cleaner effectiveness, it has become clear that there is no single or ideal solution for belt cleaning and tensioner selection. Safety of personnel and the belt itself is an important consideration when selecting a tensioner. Ease of inspection and maintenance is critical for belt cleaner effectiveness, so the tensioner must allow for quick and safe service.

The selection of a belt cleaner should be based on the duty rating of the cleaner as provided in CEMA Standard 576 and then the appropriate cleaning system selected. The system should be selected based on life cycle cost and not just the initial price. The investment for effective belt cleaning is justifiable on direct cost reduction (clean-up costs), extended component life (often 25-40%) and reduced exposure to injuries, which is directly related to reduced clean-up frequency.

*R Todd Swinderman is CEO Emeritus of Martin Engineering

Addressing unsafe work practices around mining conveyors

Due to their size, speed and high-horsepower drive motors, conveyors pose a number of risks to personnel working on or near them. In addition to all the physical danger zones, when an injury occurs, ‘fault’ is often attributed to injured workers’ actions or inactions. However, safety experts point out that injuries generally occur due to a series of factors.

“Accidents are typically a result of a complex combination of probabilities, rather than a single unsafe act,” Martin Engineering Process Engineer, Daniel Marshall, observed. “Except for the unsafe act, it can be said that the accident would not have occurred if there was a safer design, better maintenance or less pressure for production.”

Assessing the risk of a conveyor

A thorough risk assessment by trained professionals is the ideal way to bridge the gap between workers and managers when the rules need review, to identify hazards and implement controls to reduce risks.

“A belt conveyor is a powerful machine with thousands of moving parts,” Marshall continued. “These moving components might severely injure a worker and can produce that injury in a fraction of a second.”

A typical conveyor belt moves at a relatively constant speed, commonly running between 0.5-10 m/s. At the very minimum, a worker who inadvertently touches a running conveyor belt – even with world-class reaction time and total focus on the danger of a conveyor – will come in contact with at least one carrying idler, and the potential is there to hit return idlers, chute uprights, stringer supports, pulleys and drives. The results are often disastrous.

Working around a moving conveyor

It has been estimated that two thirds of the fatalities involving conveyor belts take place while the belt is moving, usually because of a worker becoming entangled or crushed by moving equipment. Most of these take place when maintenance or housekeeping is being done on or around an energised conveyor.

Conveyor service should be performed only when the belt is properly locked, tagged, blocked and tested

These fatalities are generally caused by two compounding practices. The first is performing maintenance without thoroughly locking, tagging, blocking and testing the conveyor. Another unsafe practice is touching a moving conveyor belt with a tool or implement of any kind. When these two choices are combined, the results are usually severe and often fatal. Even working on a conveyor that is turned off, but not locked out, can lead to tragedy.

Workaround and shortcuts

“An intelligent and creative worker will often invent or discover ways to expedite certain functions or make work easier,” Marshall said. “Unfortunately, some of these shortcuts bypass safety hardware and/or best practices, putting the worker in harm’s way.”

The most common of these workarounds involves the “improper locking out” of a conveyor system, Martin Engineering says. The purpose of a lockout is to de-energise all sources of energy, whether latent or active. Failure to properly lockout can exist in many forms – varying from disregarding lockout requirements, to working on a moving conveyor, to improperly stopping the conveyor. An example would be pulling the emergency stop cord and assuming that the conveyor is de-energised.

Another common workaround involves entering a “confined space” without following established procedures. A confined space is any enclosure that is large enough and configured so that an employee can enter and perform assigned work, has limited or restricted means for entry or exit and is not designed for continuous employee occupancy. Very specific rules apply to workers when dealing with confined spaces. Failure to follow those rules can result in increased danger or death, Martin Engineering says.

Other potential unsafe behaviors include crossing a conveyor in a risky manner. Conveyor belts are often lengthy systems bisecting a production facility. Workers may be required to cross a conveyor line to get to an area in need of service or maintenance. To save time, a worker is likely to step over or cross under a conveyor.

“Crossing under” offers multiple hazards, according to the company. If any of the worker’s body parts come in contact with the moving conveyor, it will either act like a grinder and abrade the skin or pull the worker toward rolling components. Crossing under also places the worker at risk from falling objects.

Taking a shortcut by crossing over or under a conveyor can lead to injury

“Crossing over” a conveyor without using a designed and designated crossover structure comes with dangers, as well. There is a high potential for a slip and fall. If lucky, the worker may fall on the ground; if not, the worker will fall onto the conveyor belt. If the conveyor is in operation, the worker may be carried downstream. This can result in contact with the conveyor structure and rolling components or being thrown off the conveyor at the discharge. The safe approach to crossing a conveyor is to use a designated crossover or cross-under point engineered for that purpose, Martin Engineering says.

Anything in a worker’s line of travel is a potential “obstruction”. These can range from piles of spillage, items lying on the walkway or work areas, as well as low overheads. An obstruction can cause several hazards, the most obvious being the opportunity for a trip or fall. If the obstruction is in the middle of the walkway, a worker will have to go around it. If that revised path brings the worker closer to a conveyor, this decision places the worker closer to the hazards of the conveyor.

Neglected safety and control mechanisms

“Emergency stop pull cords are the last line of defence if the belt needs to be stopped quickly in response to an entrapment or impending equipment failure,” Marshall said. “The reaction time when such an event occurs is usually extremely brief, so workers need a way to stop the conveyor as fast as possible. In addition, the belt will not halt immediately and must coast to a stop. If the cord is broken, the switch is not working or the system is disabled, workers have lost the one final tool they have to protect themselves.”

The multiplying effect of unsafe practices

Often an accident occurs due to a combination of several poor work practices. A Mine Safety and Health Administration (MSHA) Fatalgram from 1999 in the USA recounts an event that caused a fatality at a mine when a worker entered an unguarded area alone, near an operating conveyor that was not locked out. The worker’s clothing then became trapped in the conveyor’s operating tail pulley. Four unsafe practices and two unsafe areas combined to produce a catastrophic event. Any individual factor may have led to injury or even death, but the combination essentially sealed the worker’s fate.

In a 2003 study, ConocoPhillips Marine found a correlation between fatalities and unsafe practices. The study showed that for every fatality there are an estimated 300,000 unsafe behaviors.

The research also quantified lost-time accidents, recordable injuries, and near misses. These are independent variables, so the numbers do not mean that lost day incident number 31 will be a fatality. But they do indicate that there is a statistical probability of a fatality for every 30 lost workday incidents. As a result, statistically speaking, an effective way to reduce fatalities is to reduce unsafe behaviors.

The most effective way to reduce fatalities is to minimise unsafe behaviors

“While even one unsafe practice has the statistical potential to lead to serious repercussions, conveyor accidents are rarely the result of a single action,” Marshall concluded. “More often, they result from a combination of company culture and unwise decisions. If workers can eliminate these unsafe practices and minimise their presence in danger zones, their chances of avoiding an accident will improve considerably.”

Martin Engineering goes autonomous with N2 Twist Tensioner for conveyor belts

Martin Engineering has introduced an autonomous tensioning system that, it says, continuously monitors and delivers proper cleaner tension on conveyor belts.

By using Martin Engineering’s new smart technology platform to maintain proper blade-to-belt pressure, the N2® Twist™ Tensioner provides the best possible cleaning performance throughout the life of the blade, according to the company. The system also alerts operators on the Martin Smart Device Manager App when the blade needs changing or if there is an abnormal condition.

“The result is efficient cleaning, increased safety, reduced labour and a lower cost of operation,” the company said.

Andrew Timmerman, Product Development Engineer at Martin Engineering, said the company designed the unit for heavy-duty applications and tested it outdoors in punishing environments and applications.

“The N2 Twist Tensioner has proven itself to be a rugged and highly effective way to maximise both cleaning efficiency and blade life,” he added.

Located on the head pulley, primary belt cleaners commonly have a twist, ratchet or spring tensioner to ensure the cleaner blade stays in consistent contact with the conveyor belt for proper cleaning and material discharge, Martin Engineering says. Prior to the new design, belt tensioners had to be monitored and adjusted manually, in some applications on a daily basis, so they would maintain optimum pressure and carryback removal. Estimating when blades needed changing was often a guessing game that, if left too long, could lead to belt damage, according to the company.

The company continued: “Inadequate tensioning causes carryback to cling to the belt and spill along its path, piling up under the conveyor and emitting excessive dust. This requires extra labour for clean-up and can affect air quality. Over-tensioning leads to friction damage to the carrying side of the belt, premature blade wear and potential splice damage. Both scenarios create unsafe work conditions and raise the cost of operation significantly.”

The N2 Twist Tensioner automatically maintains precise cleaning pressure throughout the entire life of the blade, without maintenance, Martin Engineering says. The tensioner applies the proper amount of torque to deliver optimum cleaning pressure at the blade tip, supporting the Constant Angle Radial Pressure cleaner design that, it says, withstands the force of heavy bulk cargo but retains a consistently tight seal across the belt profile.

Martin Engineering’s smart technology platform monitors blade wear and informs operators when the blade needs changing from control systems that are housed in a durable weather-resistant NEMA 4 control box. Experts recommend changing blades before there is a chance of detachment or a “pull through” (inversion under the head pulley). In the event of a premature pull through, operators are alerted, and the tensioner’s internal self-relieving coupling rolls over. A blade detachment also triggers an alert allowing operators to quickly shut down the system and avoid expensive belt damage.

The electrical system runs both the tensioning system and the sensors, with the unit powered by a rechargeable 12 v battery life. It can also be specified to run on 110-220 VAC.

Martin Engineering concluded: “The N2 Twist Tensioner and Smart Device Manager App ease the burden on managers and workers so they can focus their attention on other critical details of the operation. Precise tensioning and improved belt cleaning reduce the volume of dust and spillage from carryback, improving workplace safety and decreasing the labour needed to maintain and clean around the discharge zone.”

Martin Engineering goes virtual with conveyor training

With in-person training curtailed for the foreseeable future due to COVID-19 restrictions, Martin Engineering says it has developed an extensive array of tools to continue its tradition of educating those who maintain, manage and design conveyors for industrial operations.

The result is a wide range of globally-available options to help improve safety and efficiency, reduce maintenance expenditures and extend equipment life, ultimately contributing to greater profitability, it says.

“The pandemic has impacted our ability to teach traditional classes at customer sites,” PE Todd Swinderman, CEO Emeritus of Martin Engineering and an industry veteran with more than 40 years of hands-on experience, said. “But it doesn’t reduce the need for conveyor operators and facility managers to obtain the benefits and continuing education credits those sessions provide.”

In response to the restrictions that the virus has placed on face-to-face learning, Martin has created a series of interactive online modules based on the same non-commercial curriculum it has produced over the years. Designed to keep attendees engaged and organised into 90-120 minute segments, the virtual classes cover topics such as best practices for safety, fugitive material control and belt tracking. Upon completion, attendees are eligible to receive either Professional Development Unit (PDU) or Continuing Education Unit (CEU) credits.

“The Foundations™ online seminars deliver non-commercial, topic-specific problem-solving information that can be put to immediate use,” Swinderman said. “There’s no sales pitch, and even the most remote locations can take advantage,” he added.

Customer Development Manager, Jerad Heitzler, an instructor of Martin’s safety workshops since 2010, said: “Conveyors are one of the best productivity-enhancing tools available, but conveyor injuries cost employers millions of dollars annually. Because of the size of their material cargoes, the speed of their operation, and the amount of energy they consume and contain, conveyors have been shown to be a leading cause of industrial accidents, including serious injuries and fatalities. But injuries are preventable with the right training, preparation and safety precautions.”

According to Heitzler, the company’s preferred platform is Zoom, but its expert trainers also have experience with Google Meet, Microsoft Teams and Webex.

“Our platform has been built to increase attendee engagement as much as possible,” Heitzler added. “Many trainers don’t use the available platform features effectively, because they were thrust into online training as a result of the pandemic. But we’ve worked hard at using engagement features to increase learner participation, with options such as a raise hand button, chat, Q and A, screen sharing, white boards, private breakout rooms and polling.”

Heitzler said the Martin team has taught around 2,000 attendees using video conferencing since the onset of the virus.

“We’ve presented these modules to learners in coal handling plants, cement manufacturing, aggregate production and pulp and paper mills,” he said. “We’ve also provided training for industry consultants, service providers and engineering firms who design conveyors and plants.”

Swinderman estimates the firm has trained more than 50,000 miners, operators, maintenance staff and management personnel around the world.

There are two standard tracks: one for maintenance and operations personnel that stresses safe work practices and solutions to common conveyor problems, and one designed for technical and management personnel that emphasises the design and operation of conveyors for safety and productivity. In addition, Martin trainers and engineers can custom design programs not only for customers using conveyors but for those needing training on the application of industrial vibration, air cannons and silo cleaning.

“Both methods of training are highly interactive, effective and non-commercial, focusing on delivering timely information that can be put to immediate use,” Swinderman concluded.

Martin Engineering’s Mr. Blade service offering comes to US Mid-Atlantic region

The use of factory-trained, OSHA- and MSHA-certified experts for maintenance of bulk handling systems has taken another step forward as Martin Engineering establishes its newest Mr. Blade™ territory, serving the Mid-Atlantic region of the USA, the company says.

Introduced in 2015, the network is a “unique factory-direct service program”, delivering replacement belt cleaner blades, air cannon valves and other Martin products, specified and custom-fitted on-site and installed free of charge. Further, Martin service technicians will replace the main frame and tensioner of any belt cleaner as needed – also at no charge – as part of the Mr. Blade service relationship.

The new territory is part of a larger initiative to deliver factory-direct service to customers around the world. The Mr. Blade program is currently up and running in the USA, UK and Italy, with additional launches planned for next year. The company estimates that it is currently responsible for about 10,000 conveyor belts worldwide as part of its managed services program.

“Martin assures accurately-sized and professionally installed replacement blades that are matched to the specific application, providing optimum cleaning performance and service life,” the company said. “The company ensures customer satisfaction with its exclusive Forever Guarantee, which specifies that users will experience better cleaning, longer service life and lowest cost of ownership.”

Initial targets for the new territory will be facilities producing or handling sand, aggregate or cement.

Martin Engineering Senior Customer Support Specialist, Marty Smith, explained: “Plants in just about every industry are being asked to do more with limited resources. Maintenance personnel often don’t have the time or training to safely and efficiently perform belt cleaner inspections or air cannon service when needed. Customers really appreciate having a dedicated technician who makes regular visits, so employees can focus on core business activities.”

National Sales Manager for Wear Components, Alan Highton, says shifting the maintenance responsibility to a trusted partner through this kind of service relationship is one way that bulk handlers can continue to streamline their operations, improving the performance and safety of their bulk handling systems at the same time.

“Unlike most suppliers, we have chosen not to use third-party service providers, who typically don’t have the specific expertise to optimise these systems,” Highton said.

“The idea behind the Mr. Blade program is to deliver an unequalled level of service using highly efficient, regionalised systems,” he added. “Our technicians really get to know the conveyors they’re visiting, and with the monitoring systems we now have in place, we’re able to deliver proactive service in advance of a breakdown, replacing worn or failing components before they lead to an event that stops production.”

The company is also taking steps to help customers whose facilities have limited access during the COVID-19 pandemic by partnering with their maintenance staff to remotely train employees to effectively maintain their conveyor systems, offering guidelines on preventive maintenance, inspections and replacement blade ordering. Factory-direct technicians remain in close contact with periodic check-ins and provide key parameters to assure optimum performance, according to the company.

As part of the Mr. Blade service, Martin will install its Position Indicators on every primary cleaner free of charge to deliver remote monitoring for qualifying customers, allowing technicians and operations personnel to access detailed information on conditions and remaining service life via Wi-Fi or cell phone. The monitoring system alerts service personnel when re-tensioning or replacement is required, or when abnormal conditions occur.

Also included are regularly-scheduled inspections, adjustment and blade replacement as required on all Martin belt cleaning systems, as well as the company’s multi-point Walk-the-Belt audits based on worldwide best practices. All services are covered by the price of components, with no contract required, Martin claims.

Highton said the new territory will cover five states: Pennsylvania, New York, Maryland, New Jersey and Delaware. The company has begun serving customers with two technicians in specially-equipped vans, each outfitted with a fresh supply of 8 ft (2.4 m) blade lengths and equipped with a band saw, milling machine and all tools required to achieve a custom fit, accurate installation and precise tensioning.

The vans are designed as mobile business units, with technicians able to electronically enter and update data on each customer system right at the site. With a lifetime record of all belt cleaning equipment, customers will have access to details on the mounting assembly, tensioner and blade wear life, along with total annual cost information for budgeting purposes, the company claims.

Smith said: “Consistent attention to the cleaners helps deliver maximum performance and wear life, minimising component failures and unscheduled shutdowns. And, if there is a breakdown, service is available from MSHA-certified technicians capable of repairing any brand or style of cleaner. We can even supply retrofit blades to fit belt cleaners from any manufacturer.”

Martin Engineering on preventing accumulation in mining hoppers and chutes

Accumulation or blockages in storage systems and build-up in process vessels at mine sites can impede material movement, causing bottlenecks that interfere with equipment performance, reduces process efficiency and put a choke hold on an operation’s profitability, according to Martin Engineering.

Efficient material flow is a critical element of wet mining processes such as stoping, hydraulic mining and wet dredging, the company says. Poor material flow also raises maintenance expenses, diverting manpower from core activities and, in some cases, introducing safety risks for personnel.

“Most systems suffer from some amount of accumulation on vessel walls, which can rob plant owners of the storage systems in which they’ve invested,” Brad Pronschinske, Global Director of Air Cannons Business Group for Martin Engineering, said. “These buildups reduce material flow, decreasing the ‘live’ capacity of the vessel and the efficiency of the bulk handling system overall.”

Pronschinske said the accumulations tend to take one of several forms: arches, plugs, build-ups or “rat holes”.

He added: “If they become severe enough, flow problems can bring production to a complete stop.”

Although many plants still use manual techniques to remove buildup, the cost of labour and periodic shutdowns has led some producers to investigate more effective methods for dealing with this common production issue, according to the company.

Buildup versus throughput

Even well-designed processes can experience accumulations, which have a significant impact on output and profitability. Changes in process conditions, raw materials or weather can all influence material flow, and even small amounts of accumulation can grow into a serious blockage.

Beyond moisture content, there are many causes of raw material buildup on vessel walls, according to Martin Engineering.
Some metals contain naturally occurring magnetic properties; nearly 90% of the earth’s crust contains silica, and the sharp crystalline structure can contribute to buildup. Other factors can include the surface friction of the silo walls, the shape of the vessel, the angle of the slope and the size of the material being loaded.

Lost production is probably the most conspicuous cost of these flow problems, according to the company, but the expense can become apparent in a variety of other ways.

Shutdowns to clear the restricted flow cost valuable process time and maintenance hours, while wasting energy during re-start. Refractory walls can be worn or damaged by tools or cleaning techniques. When access is difficult, removing material blockages may also introduce safety risks for personnel. Scaffolds or ladders might be needed to reach access points, and staff can risk exposure to hot debris, dust or gases when chunks of material are released.

Many of the most common problem areas for accumulation are classified as confined spaces, requiring a special permit for workers to enter and perform work.

“The consequences of untrained or inexperienced staff entering a silo or hopper can be disastrous, including physical injury, burial and asphyxiation,” Martin Engineering says. “Disrupted material adhered to the sides of the vessel can suddenly break loose and fall on a worker. If the discharge door is in the open position, cargo can suddenly evacuate, causing unsecured workers to get caught in the flow. Cleaning vessels containing combustible dust – without proper testing, ventilation and safety measures – could even result in a deadly explosion.”

Getting professional help

“While some large facilities choose to make the capital investment to purchase their own cleaning gear to clear process equipment and storage vessels – as well as train personnel – others are finding it more sensible to schedule regular cleanings by specially-trained contractors,” Pronschinske says. “Given the costs of labour, lost time and potential risk to employees, this can often be accomplished for less than the total investment of in-house cleanouts.”

Safe, effective cleaning requires tools that work inside the silo
from the top, controlled by personnel outside

At one location, for example, the blockage was so severe in one silo that it had been out of use for years. While it took the outside contractor almost two weeks to fully evacuate the vessel, the process restored 3,500 tons (3,175 t) of storage capacity, according to the company.

At another facility, the crew was able to remove enough ‘lost’ product that the value of the recovered material actually paid for the cost of the cleaning.

“In short, regular cleaning of storage vessels can quickly turn into an economic benefit – not an expense, but rather an investment with a measurable return on investment,” the company says.

The costs of cleaning

There are a few types of equipment used for this purpose.

“One operates like an industrial-strength ‘weed whip’ rotating a set of flails against the material in the vessel,” Martin Engineering says. “This approach eliminates the need for confined space entry and hazardous cleaning techniques, typically allowing the material to be recaptured and returned to the process stream.”

The whip can be set up quickly outside the vessel, and it is portable enough to move easily around various bin sizes and shapes, according to the company. Typically lowered into the vessel from the top and then working from the bottom up to safely dislodge accumulation, the pneumatic cutting head delivers powerful cleaning action to remove buildup from walls and chutes without damaging the refractory.

Technicians lower the device all the way down through the topside opening, then start at the bottom of the buildup and work their way up, undercutting the wall accumulation as it falls by its own weight, the company explains. “In extreme cases, a ‘bin drill’ can be used to clear a 12 in (305 mm) pathway as deep as 150 ft (45 m) to start the process.”

Flow aids

Regular cleaning is one approach to keeping materials flowing freely by removing buildups from silo walls, but there are other flow aids which may reduce the need for cleaning or even eliminate it, according to Martin Engineering.

Industrial vibrators for bin & chute applications can reduce or even eliminate the need for cleaning

One method is through industrial vibrators designed for bin and chute applications.

“Electric vibrators are generally the most efficient, delivering the longest life, low maintenance and low noise,” it said. “The initial cost for an electric vibrator is higher than for pneumatic designs, but the operating cost is lower. Turbine vibrators are the most efficient and quietest of the pneumatic designs, making them well suited to applications in which low noise, high efficiency and low initial cost are desired.”

Air cannons (pictured) are another approach to maintaining good material flow, according to the company, particularly in larger vessels. Also known as an air blaster, the air cannon is a flow aid device that can be found in mining, coal handling and many other industries. Applications vary widely, from emptying bulk material storage vessels to purging boiler ash to cleaning high-temperature gas ducts.

“In the mining industry, air cannons are frequently specified to eliminate build-ups in hoppers, storage vessels, transfer chutes, bins and other production bottlenecks,” the company said. “They can also be found in mineral processing plants where metals are extracted using processes creating slurries and other wet, tacky tailings.”

Air cannon technology has been used in mining and material processing for many years, helping to improve flow and reduce maintenance, according to the company. The timed discharge of a directed air blast can prevent accumulation or blockages that reduce process efficiency and raise maintenance expenses.

In underground mines with potentially explosive dust, manual firing of cannons without the use of electrical solenoids is an option, the company says. “By facilitating flow and minimising build-up, air cannons help bulk material handlers minimise the need for process interruptions and manual labour,” Martin Engineering claims.

The two basic components of an air cannon are a fast-acting, high-flow valve and a pressure vessel (tank). The device performs work when compressed air (or some other inert gas) in the tank is suddenly released by the valve and directed through a nozzle, which is strategically positioned in the tower, duct, chute or other location. Often installed in a series and precisely sequenced for maximum effect, the network can be timed to best suit individual process conditions or material characteristics, the company says.

Pronschinske concluded: “The core message for mines and material processors is that they don’t have to put up with accumulation problems and the additional expenses they can cause. There are a number of approaches that can help resolve those issues before they turn into expensive downtime, lost material and safety hazards.”

Martin Engineering conveys speciality contractor message

Using a specialty contractor for installation and ongoing maintenance of conveyor belts contributes to safer and more efficient production – with less unscheduled downtime – and, in the long run, saves money and reduces injuries, according to Martin Engineering.

“Performance problems with conveyor components and systems can frequently be traced to improper installation or insufficient maintenance,” the bulk material handling innovator says. “It is recommended that the component manufacturer or expert contractor install equipment on both new and retrofit applications.”

Serious performance problems stem from a lack of proper maintenance, which is exacerbated by several factors.

Training and retention

The time and resources required to train employees on equipment and certify them to conduct certain procedures such as confined space entry, electrical work, etc can be a significant ongoing expense, Martin Engineering says.

As workers become more experienced and gain certifications to properly maintain efficient systems, their value in the marketplace rises. This leads to retention becoming an issue.

“In contrast, specialty contractors must be experienced, knowledgeable and certified to conduct the appointed maintenance, and it’s up to the contracted company to retain and train that staff,” the company says.

Maintenance danger zones

Due to a greater emphasis on safety and the expensive consequences of unscheduled downtime, bulk handlers are being more meticulous about conveyor operation and maintenance, according to Martin Engineering.

This increased scrutiny includes regular cleaning of spillage, improved dust control, and additional monitoring and maintenance, which expose employees to a moving system more often. These changes introduce a variety of hazards.

Conveyor danger zones where work injuries are likely to occur include:

  • Loading zone;
  • Discharge zone;
  • Mechanical/electrical equipment;
  • Rotating pinch/shear points;
  • Underneath the conveyor; and
  • Unguarded reach-in points.
Danger zones exist along the entire length of the belt, many at maintenance points

“Most common conveyor-related issues are found across a wide range of industries, and personnel who work around the equipment on a daily basis often become complacent about the conditions, viewing issues as an unavoidable outcome of production rather than abnormalities in need of resolution,” the company says.

“An experienced maintenance contractor recognises these problems and may present solutions that internal resources have overlooked. The improvements are designed to reduce employee exposure, improve workplace safety and maximise productivity.”

Service contract types

Maintenance programs differ by provider and may be customisable to suit individual customers, but they generally fall into three categories: inspection/report, cleaning/servicing and full service.

A scheduled inspection and report contract results in a specialty contractor coming to site to thoroughly examine a system – from belt health to equipment function to the surrounding environment – and identify potential issues. A report is produced that presents findings and offers solutions.

The cleaning and servicing contracts are perhaps the most common, Martin Engineering says.

From spillage and silo cleaning to monitoring and changing belt cleaner blades, services can be very specific and fill gaps where maintenance crews might be overstretched. “The first advantage to this is that a conveyor can be surveyed without requiring the attention of plant personnel, freeing them to go about their usual tasks,” the company says. “A second advantage is that the outside surveyor is an expert in proper conveyor practices and current governmental regulations.”

At the highest level, a full service and maintenance contract sends trained technicians who take accountability for monitoring, maintaining and reporting on every level of system function. They replace wear components when needed and propose required upgrades to maximise efficiency, safety and uptime.

“This provides operators with cost certainty, making it easier to project and manage the cost of operation,” the company says.

Return on investment (ROI)

Increasing speeds and volumes on older conveyor systems designed for lower production levels contribute to workplace injuries and increased downtime. Capital investments in newer semi- or fully-automated systems designed for higher throughput require less labour, but the maintenance staff needs to be highly trained by specialised technicians.

Maintenance service contracts deliver the best ROI, according to Martin Engineering, through a series of factors:

  • Compliance – the contractor points out compliance issues and offers solutions prior to expensive fines and violations;
  • Injuries/liability – contractors rely on a strict set of safety procedures to conduct maintenance, reducing liability;
  • Efficiency – maintenance service contracts focus on improving and sustaining uptime with the least capital investment possible;
  • Consistency – contractors have a clear directive and are not affected by internal factors (labour disputes, morale, etc); and
  • Cost of operation – with a defined scope of work on a set budget, along with clear reporting and recommendations on pending needs, operators can better forecast improvements and control labour costs, further improving ROI over time.

Maintenance service contracts are not just a way of controlling and potentially reducing the cost of operation, they are also a safety mechanism.

For example, one case study showed a 79% reduction in lost time incidents and a 40% improvement in production using specialty services, which demonstrated payback in days from an annual specialty maintenance contract.

“Workloads may preclude staff from maintaining proper compliance or they just might not notice some violations,” the company says. “Outside resources take ownership of the plant’s efficient and productive use of the conveyor system and strive to improve conveyor efficiency, maximise equipment life and safety to add value to the operation.”

At the core of the issue is lower operating costs and improved production. The work should match or improve efficiency regarding downtime and throughput. If the criteria of compliance, cost savings and efficiency are met, then the maintenance service contract has provided a tenable ongoing solution, Martin Engineering concluded.

Martin Engineering delves into the danger zone for conveyor belt best practice

In bulk material handling applications, a conveyor is typically a massive, complex and extremely powerful system. It is usually constructed of rubber belting, set on rolling idlers, wrapped around large steel drums at each end and driven by a high-torque motor. As such, a conveyor presents enough danger zones that the entire system should be considered a hazard, according to Martin Engineering.

In most applications, a conveyor belt moves at a relatively constant speed, commonly running somewhere between 0.5-10 m/s. An Olympic sprinter has a reaction time of about 0.18 seconds when poised at the starting line and totally focused on the race. If this athlete becomes tangled in a conveyor belt traveling 1.5 m/s, the person would be carried 0.27 m before even realising what has happened.

A ‘regular’ worker would likely require a longer time to react, Martin Engineering says. For simplicity’s sake, assume it would be twice the athlete’s reaction time, so the worker would be pulled twice as far, introducing the potential to strike many more components or to be pulled farther and harder into the first one.

In addition, most conveyors are engineered with the ability to start remotely. The system may go from dormant to active at any time at the push of a button, and that ability can suddenly catch a worker unaware, leading to serious injury or death, the company says.

Martin Engineering Process Engineer, Dan Marshall, said: “When a conveyor belt is moving, there will usually be more tension on the carrying side. If the conveyor is merely stopped and de-energised, that tension may remain in the belt in the form of stored energy.”

A system under tension will always try to approach equilibrium, according to Marshall; that is, it will try to release the energy. This release will likely come in the form of a pulley slip, which occurs when the belt slides around the head pulley to equalise the tension. The distance the belt will move is proportional to the amount of tension stored and the belt’s modulus (elasticity), possibly several feet. If a worker is on the belt or close enough to be pulled in during this sudden release of energy, injuries or death can occur.

“There’s a simple rule of thumb regarding conveyors: if it’s moving, don’t touch it,” Marshall continued. “The most common way to prevent inadvertent contact is with suitable guarding that renders the moving components inaccessible.”

For maintenance or repairs, procedures for lockout/tagout/block-out/test-out should always be followed when working on a stationary conveyor, and systems should be equipped with anti-rollback devices (also known as backstops) on the head pulley.

Many of the moving parts on a conveyor belt system are rotating components. These parts include idlers, drive shafts, couplings, pulleys and speed sensors. Items rotating at a high speed pose the risk of entanglement or entrapment.

“All moving machine parts should be guarded with adequately constructed, properly installed, functioning and well-maintained guards,” Marshall said.

There are many pinch points on a conveyor, components that the belt touches or comes near, including the drive pulleys, snub pulleys, idlers, stringer, chute walls and deflectors. If a worker’s limb travels with a conveyor belt, it will meet one of these components. The limb, as well as its attached worker, will become trapped between the belt and the obstruction.

The same thing can happen with a tool, which can pull a worker into the entrapment faster than the person can let go.

“Effective fixed guards should be absolute in their protection; workers should not be able to reach around, under, through or over the barrier separating them from moving components,” Marshall added.

Many of the fatalities around conveyors have happened when a worker was cleaning fugitive material from the structure or components of a conveyor system. The process of cleaning may put a worker in proximity to a very dangerous machine, according to Martin Engineering. The need to shovel, sweep or hose off accumulations puts the worker within arm’s length of the conveyor, and often closer.

Airborne dust can cause numerous health risks, ranging from material build-up in the lungs to explosions. Categorised as either respirable or inhalable according to particle size, dry, solid dust particles generally range from about 1 to 100 microns in diameter.

According to the EPA, inhalable coarse particles are 2.5-10 microns in size. They are typically caught by the human nose, throat or upper respiratory tract. In contrast, fine respirable particles (under 2.5 microns) can penetrate beyond the body’s natural cleaning mechanisms (cilia and mucous membranes), traveling deep into the lungs and causing long-term or chronic breathing issues.

While it is virtually impossible to prevent all fugitive material from escaping a conveyor structure, taking practical steps to minimise it as much as possible helps reduce the dangers it can introduce, the company says. When clean-up is necessary, performing the job while the conveyor is running should not be an option. Operators concerned with the cost of lost production from stopping a conveyor to clean need only consider the consequences of an accident to confirm the wisdom of this rule.

Until recently, the engineering of belt conveyors to carry bulk materials hadn’t changed much in the last half-century, despite the fact that virtually every requirement for safety, regulatory compliance and production performance has been raised during that time. Standards continue to tighten and industry best practices now often exceed government requirements.

“Using these new and emerging technologies, even poorly performing conveyors often don’t need to be replaced or rebuilt, but merely modified and reconfigured by knowledgeable and experienced technicians installing the right modern equipment,” Marshall concluded. “Specialised conveyor training and trusted resources from global suppliers are helping to raise operator awareness to make conveyor systems cleaner, safer and more productive.”