Tag Archives: mining conveyors

Metso Outotec bags overland and in-plant conveyor order from the Americas

Metso Outotec says it has been awarded an order for a large belt conveyor package for delivery to a mining customer in the Americas.

The value of the order is around €60 million ($61 million), of which a third was booked in the Minerals division’s June-quarter orders received and the rest in the September quarter.

Metso Outotec’s scope of delivery includes 3.5 km overland and in-plant conveyors as well as shuttle head conveyors with a nominal equipment capacity of up to 21,000 t/h.

Metso Outotec says it has the capability to design and deliver even the largest conveyor systems with high project quality, with its overland solutions providing flexible and reliable material transportation with increased energy savings for the lowest total cost of ownership.

Martin Engineering on ‘carryback’ issues with conveyors

“Carryback” is defined as the material that fails to unload from a conveyor belt, adhering to the belt and typically falling off at some point other than the intended discharge, and it’s one of the main sources of fugitive materials, estimated to account for 85% of all conveyor maintenance issues, according to Martin Engineering.

Accumulation on moving components from dirty belts can cause premature wear and require frequent cleanup, which exposes workers to potential workplace injuries and respiratory diseases, it warns.

It can be shown practically and theoretically that a conveyor belt cannot be cleaned 100% because the surface of the belt and the blades are not without imperfections. However, this does not do away with the need for operators to take a proactive approach to keeping the belt clean. Most industries have gravitated to basic mechanical scraping with a metal or elastomeric blade for flat rubber or PVC belting as the best combination of effectiveness, ease of maintenance and low belt wear to yield the lowest cost of ownership.

Belt cleaning effectiveness varies day to day with changing conditions and the number and type of cleaners applied, as well as the maintenance they receive. Keeping the material in the process is always better than letting it accumulate on components and build up under the conveyor. Without effective belt cleaning, experience has shown that as much as 3% of the total cargo can be lost due to spillage, dust and carryback.

The exposure to hazards and injuries is also reduced when less cleanup is required, saving significant – but seldom considered – indirect costs. The key to consistent cleaning effectiveness is to control the process through proper selection, installation, inspection and maintenance of the belt cleaning system and establish a safe cleanup routine and schedule.

The use of multiple mechanical scrapers on a belt has been accepted for quite some time as an effective cleaning approach. In most operations, multiple cleaners are required to reduce the carryback to a safe, acceptable level while limiting manual cleanup to weekly or even monthly tasks.

Effectiveness vs efficiency

The undulating action of the loaded belt passing over idlers tends to cause fines and moisture to migrate and compact on the surface of the belt. The amount of carryback that clings to the belt can range from a few grams to a few kilograms per square meter. The level of belt cleaning required is a function of the operational schedule and method of collecting/disposing of the carryback that is cleaned from the belt or dislodged by return idlers and collects outside of the conveyor discharge chute.

When discussing the efficiency of a belt cleaner, it’s meaningless to talk about efficiency without stating the initial level of carryback. When considering the beginning and ending levels of carryback as a measure of improvement, effectiveness is a better term. Some guidelines do exist. The US Bureau of Mines states that an average of 100 g/sq.m of carryback is a reasonable level of performance for belt cleaning. At this level, a 1,200-mm wide belt traveling 2 m/s and operating 24/7 would create a cleanup workload of about 7 t/d, a significant labour investment that also increases worker exposure to a moving conveyor and the associated risks.

Carryback level determines the cleanup schedule, but, in reality, a typical belt cleaner loses effectiveness over time due to wear, lack of inspection and maintenance. On systems with average or poor maintenance, effectiveness values are generally in the range of 40-60%, thus the need for multiple cleaners.

Cleaning location

Unfortunately, designers often focus on the lowest installed cost of the structure around the head and snub pulleys, without allowing enough space for optimum cleaner installation. The figure below shows the clear areas needed on a discharge chute for installation of belt cleaners in the optimum positions. The installations should be at an ergonomic height above the work platform to encourage proper inspection and service. Consideration in the design stage for locating cleaners in the optimum locations will lead to more effective inspections, maintenance and belt cleaner performance.

Belt cleaning positions (© 2022 Martin Engineering)

Belt cleaners can be placed anywhere along the return run of the belt, as long as the belt is supported in some fashion. Since it’s desirable for the carryback cleaned from the belt to be returned to the main material flow, most belt cleaners are installed inside the discharge chute. Cleaning on the head pulley – labeled the ‘primary cleaning position’ – is preferred. Cleaning the dirty side of the belt before it reaches a snub, bend pulley or return idlers is considered less desirable, requiring a dribble chute for cleaners in the secondary position.

Typical installation of primary, secondary and tertiary cleaners (© 2022 Martin Engineering)

The secondary position is complicated by another fact: the nature of carryback is such that it can adhere to vertical surfaces and not flow down a sloped dribble chute. A tertiary position is sometimes required for difficult materials or critical applications such as conveying over wetlands. In such cases, the tertiary cleaners are often enclosed in a spray box and the effluent directed to a settling basin.

Belt cleaning pressure & blade wear

Without enough cleaning pressure, the blade cannot stay in contact with the belt, resulting in poor carryback removal effectiveness and increased blade and belt wear. With too much cleaning pressure, the cleaning performance declines due to deflection of the elastomeric blade or metal blade indentation into the rubber belt. Power consumption also increases dramatically with excessive cleaning pressure.

Elastomeric primary blade pressure at a positive rake angle (left) and metal secondary blade pressure at zero rake angle (right)

Keeping a belt cleaner properly tensioned is critical for maximum effectiveness and lowest cost of ownership. The cleaning pressure usually varies over time, based on the maintenance department’s attention or lack thereof. Some manufacturers have begun to offer automatic tensioners and wear indicators which maintain the optimum cleaning pressure and alert operators when blades are worn.

Automatic tensioner maintains optimum cleaning pressure without operator intervention (© 2022 Martin Engineering)

Conclusion

Many belt cleaner systems are installed and forgotten. A survey of technicians indicated that about 25% of all belts have cleaners installed, and of that percentage only about 25% are properly maintained. Lack of inspection and maintenance results in a gradually lower level of effectiveness, higher operating cost and an increased exposure to the hazards associated with cleaning up carryback.

Effective belt cleaning starts in the design stage, with adequate space for cleaners and well-positioned work platforms for ergonomic inspection and maintenance access. Service-friendly designs improve production, minimising carryback and prolonging the life of equipment. If the cleaners are located in the optimum positions and easy to access, it is more likely that regular inspection, cleaning and maintenance will be performed, delivering optimum results.

Second Doppelmayr RopeCon goes live at Northam’s Booysendal mine

The second Doppelmayr RopeCon® system at Northam Platinum’s Booysendal platinum mine in South Africa has gone live, helping transport approximately 400 t/h of mined material over a distance of 2.8 km and a difference in elevation of -160 m.

A RopeCon system has been transporting platinum ore at Booysendal since the end of 2018, with this first installation transporting some 909 t/h of material over a circa-4.8 km distance through hilly terrain.

In December 2021, the second installation at Booysendal North was handed over to the customer.

The Booysendal North RopeCon discharges the material into the same silo from which the material is loaded onto the Booysendal South system, which makes it a perfect link in a continuous conveying line, Doppelmayr explained. Since early 2022, the second loading point along the line has been in use, too. The option of an alternative loading point was provided at tower 2. A conventional feeder conveyor transports the material to the RopeCon line where it is loaded directly onto the belt via a chute.

RopeCon, developed by Doppelmayr, offers the advantages of a ropeway and combines them with the properties of a conventional belt conveyor, according to the company. It essentially consists of a flat belt with corrugated side walls: just as on conventional belt conveyors, the belt performs the haulage function. It is driven and deflected by a drum in the head or tail station and fixed to axles arranged at regular intervals to carry it. The axles are fitted with plastic running wheels which run on fixed anchored track ropes and guide the belt. The track ropes are elevated off the ground on tower structures.

“By using the RopeCon system, the customer did not have to rely on trucks to transport the material, a definite advantage in this topographically challenging terrain with its sometimes very steep roads,” the company said. “Furthermore, using the roads only for the transport of people and supplies will have a positive effect on road maintenance costs.”

Booysendal was also particularly careful to choose a transport system that would minimise the environmental footprint of the mine. By guiding the RopeCon over towers, the space required on the ground is reduced to a minimum, or more precisely to the tower locations. At the same time, the system does not represent an insurmountable obstacle for wildlife or humans. The track crosses a number of roads, and even wildlife can roam freely underneath the RopeCon, according to Doppelmayr.

Greenland Resources makes plans to employ Doppelmayr RopeCon at Malmbjerg moly project

Greenland Resources Inc is taking a different tack to mine haulage at its Malmbjerg molybdenum project in Greenland, laying out plans in a feasibility study to use a Doppelmayr RopeCon® aerial conveyor to transport ore to the concentrator.

In a definitive feasibility study that outlined a 20-year open pit mine life with annual life of mine production of 24.1 MIb of molybdenum, Dr Ruben Shiffman, Executive Chairman, said the company had chosen to “prioritise the environment over capital expenditure”.

In addition to the planned use of a Doppelmayr rope conveyor over cheaper and less environmentally friendly diesel haul trucks – which would save the company over $80 million in capital expenditure, according to Shiffman – the company also planned to use salt water as process water in its process plant, with very low reagent concentrations to mitigate any potential environmental contamination.

The Malmbjerg project comprises of a conventional open-pit mine producing 35,000 t/d of molybdenum-rich ore for processing in a conventional base metal sulphide concentrator. The mine plan equipment fleet consists of two 34 cu.m hydraulic shovels loading 13 x 230 t haul trucks operating on 12 m benches.

The operational mining plan will utilise an economic grade control system where higher value ore will be separated and transported to the concentrator while the lower value ore will be stockpiled and processed at the end of conventional mining.

Waste rock will be stored on the west side of the deposit and used for haul road and construction activities at the mine site.

Current mining reserves dictate a mine life of 20 years where the concentrator will be fed directly from the open pit for a period of 11 years and stockpiled ore will be processed for the remaining nine years.

Ore produced from the open pit will be transported to the primary crusher and loaded onto the Doppelmayr Seilbahnen GmbH ropeway aerial conveyor for transportation to the concentrator located 21.7 km northeast of the open pit on tidewater.

“The ropeway aerial conveyor is similar to historic ore tramline systems that are employed in challenging topography where ore surface transportation systems are not topographically and economically favourable,” Greenland Resources said. “The ropeway is expected to generate electrical power for the mine site during the life of the operation.”

The ropeway aerial conveyor discharges ore into a 35,000 t “live” stockpile at the concentrator for processing. The concentrator is of a modular design constructed on barges and transported from an overseas shipyard to the project site where the barges will be permanently located in a dedicated beach location. The 35,000 t/d concentrator modular design was selected based on the economics of offsite construction and reduced concentrate production commission time.

The life of mine average mill feed grade is 0.176% MoS2 at an estimated recovery of 84.6% MoS2.

The concentrator comprises two SAG circuits feeding a conventional multi-stage flotation circuit to produce a molybdenite-rich concentrate. Due to the four-to-six-month ice-free shipping season, concentrate will be inventoried in containers on site during the non-shipping period and shipped to end users when the shipping season commences.

The estimated initial capital for the project is $820 million with $194.4 million of this being set aside for the rope conveyor.

 

Chute Technology improves the flow at Ulan operations

Chute Technology says its new coal and ore handling technologies, designed to overcome production-limiting factors at mines and bulk handling terminals throughout Australia, are proving their worth in service at the Ulan operations in New South Wales.

The technology packages are designed to eliminate potential bottlenecks, occupational health and safety issues and weak links in the production chain that can increase downtime and reduce output, Chute Technology says.

Typical issues include bin surging, bulk cleaning, spillages, blockages and reduced throughput rates, resulting in inefficient production.

According to Dennis Pomfret, Managing Director, Chute Technology, the company designed a customised chute to eliminate potential downtime for a specific section of the bypass system at the Ulan Surface Operations, which IM understands is owned by Glencore.

The new chute has dramatically reduced downtime since commissioning, according to the company, whereas the legacy arrangements were a source of multiple hours of lost production.

“The new chute allows Ulan Surface Operations to operate with a full feed rate of 2,000 t/h without any stoppages or blockages, so they can maximise their productivity and our profitability,” Pomfret said.

Chute Technology says it combines its decades of Australian and international practical engineering experience with advanced expertise in new flow enhancement and problem-solving technologies to produce modern answers to minerals and materials handling problems. The company provides audits and solutions extending from single issues at individual plants through to whole-of-process improvements extending from mines to port or point of resource use.

Pomfret said Ulan Surface Operations was looking to the future by investing in a solution designed to maximise productivity and eliminate unwanted downtime.

“We’re delighted that we could make Ulan Surface Operations’ bypass vision come to life, and it’s rewarding to see it working out in service,” he said. “Ulan Surface Operations is always looking to employ modern solutions that avoid problems in the first place, rather than cleaning up a mess after it occurs.”

Chute Technology performed an audit of current operations to gain a holistic view of current operations, before recommending the solution. The engineering audit determined that functionality of one known trouble spot, the bypass hopper and vibratory feeder, could be taken out of service and replaced with a simpler transfer chute with an in-built surge capacity.

The chute was designed in such a way that it could all be lifted and installed in one go, minimising installation downtime, the company said.

Chute Technology also designed and installed an adjustable surge control baffle device to control the height of material on the conveyor belt. The device acts like a trimmer on the end of the chute, where it trims the height of material during times of surge loading, to avoid belt overloading, side spillage and keep material heights consistent.

“We anticipate the surge control device will reduce spillage considerably, especially when taking into account the typical delays in conveyor stopping and starting sequences,” Pomfret said.

“A major consideration for the project was to design the new chute around the existing structures as much as possible, so that there was as little rework or modifications needed before installation.

“We also took into consideration that the drop height is almost 15 m. Ulan Surface Operations wished to retain their surge bin, floor structure, vibrating feeder and conveyor structures, so we designed around these as much as was possible. Additionally, the design was modular, so the installation took as little time as possible.”

Chute Technology says it selected an asymmetric chute to avoid belt mis-tracking issues, a “virtual skirtboard” to optimise the internal flow geometry and designed a single point of contact flow path so the material flow is constantly in contact with the chute from the head pulley to the receiving belt.

Pomfret concluded: “This project has been an excellent success, and we look forward to a long-term relationship with Ulan Surface Operations, as they look to maximise productivity and profitability.”

CR and KBSS collaborate on conveyor system deployments in the Pilbara

CR has announced a new partnership with KBSS to bring CR’s custom-made conveyor systems to the Pilbara of Western Australia.

KBSS is now CR’s Pilbara-based partner for mining conveyor systems, a company fully ISO accredited to Quality Management Systems, with, CR says, a reputation for delivering safe, reliable and cost-effective outcomes.

As part of the partnership, CR will be providing engineering and technical support, including on-site support, while KBSS will be looking after installation and maintenance services.

CR Business Development Manager, Paul Shankley, said: “When CR was searching for partners to bring our mining conveyor systems to the Pilbara, KBSS was the obvious pick. We both continually strive for Zero Harm whilst taking pride in bringing high-quality solutions to the global mining industry. CR are excited to collaborate with KBSS.”

CR’s mining conveyor systems are designed to maximise performance, minimise maintenance requirements and reduce total cost of ownership. Its range of conveyor components and accessories includes belt cleaning systems; belt stabilising kits; conveyor pulley lagging; conveyor skirting systems; and conveyor belt trackers.

The company said: “Our conveyor systems are designed for mines. They decrease lost product, reduce carry back, and minimise dust and spillage.”

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

Flexco to address conveyor splicing, cleaning, tracking and belt slippage needs at MINExpo

Flexco has announced its plans to exhibit at MINExpo 2021, held in Las Vegas, September 13-15, 2021, where it will be addressing splicing, cleaning, tracking and belt slippage needs.

In addition, Flexco will be introducing visitors to Flexco Elevate™ Belt Conveyor Intelligence™, a real-time belt cleaner monitoring system that, it says, harnesses the power of predictive analytics so mining operations can remotely gather critical insights that optimise belt conveyor productivity and heighten operational efficiencies.

Flexco, at the show, will be using a live, interactive dashboard to showcase how the wireless platform transfers data insights to an intuitive, cloud-based dashboard via edge technology, allowing remote monitoring of belt cleaners. Attendees will be able to see how belt cleaner challenges are communicated, analysed, and resolved using information gathered from sites across their operations.

Visitors will also be able to stop by the Flexco booth to learn how the company can help operations optimise their belt conveyors using some of our newest innovations in fastener technology.

Among those innovations is the Flexco® XP™ Staple Fastening System, which combines an enhanced applicator tool with the longest-wearing staple fastener and hinge pin on the market to produce a superior belt splice in the toughest mining applications.

Another product debuting at MINExpo under the Flexco line of mechanical fastening systems is the Super-Screw® Flexible Rubber Fastening System. Offered as part of a strategic partnership in North America with MLT Minet Lacing Technology, Super-Screw offers a faster and easier alternative to vulcanisation since it can be installed regardless of the location or accessibility of the conveyor belt and in any weather condition, the company says.

In an effort to tackle the fastest speeds, highest tonnage, and widest belts in the industry, Flexco will also be unveiling its newest belt conveyor products for carryback control. The MXS Extreme-Duty Secondary Cleaner complements its MXP Extreme-Duty Precleaner, with the duo acting as a total cleaning solution along the beltline in the most extreme mining applications, the company says. Handling belt speeds up to 10 m/s and belt widths from 1,050 to 3,000 mm, the rugged, oversized mainframes can withstand extreme pressures, while the built-in lift points and modular design make it easier to carry and install.

The unique design of the blades on the new MXD Diagonal and MXV V-Plows will also be featured at MINExpo. Capable of handling the harshest materials in the mining industry, these plows provide all the strength needed for belts with large tonnages. The design also ensures extra care has been taken to ensure the tail pulley is protected and material does not slip under the plow or jump over it, Flexco says.

In terms of maintenance tools, Flexco intends to introduce its new TUG™ HD® Belt Clamps, which are designed to secure the belt for repair, meeting the most stringent safety test standards.

Available in 6 (5.4 t) and 8 ton (7.3 t) versions, TUG HD Belt Clamps provide even tensioning across the entire belt width for ultimate strength. Modular components allow for increased versatility and portability.

New to this year’s show is also the Powered FSK™ Belt Skiver, a powered version of a manual skiver. Capable of removing belt top covers in a fraction of the time, the Powered FSK Belt Skiver is perfect for safe, easy skiving that produces a stronger splice, according to the company. The FSK is compact and easy to use anywhere on the job site, with a blade that is safely enclosed during skiving operations. Used on rubber-covered belts with top covers of 4.5 mm or more, the FSK Skiver provides skives from 1.5-9.5 mm deep in a single pass.

The booth will feature a full-size conveyor, as well as interactive displays to help attendees better understand the features and benefits of Flexco product solutions. Live demonstrations will also take place at the booth, with a focus on belt preparation, splicing, and rip repair for those interested in seeing the products at work.

Strike Resources adds Dynamic Drill and Blast, Lucas TCS to Paulsens East team

Strike Resources, after an extensive evaluation, has entered into Early Contractor Involvement Services Agreements with the preferred contractors to provide drill and blast, mining, crushing and screening services and civil works (including the haulage road and mine site) for its Paulsens East iron ore mine in Western Australia.

Dynamic Drill and Blast has been selected for the provision of drill and blast services, and Lucas Total Contract Solutions has been selected for the provision of mining, crushing and screening services, plus the civil works required for Paulsens East, including construction of the 18 km haulage road (from the mine site to Nanutarra Road), establishment of the Mining Operations Centre (MOC) and siteworks for the mining village.

Strike, which is developing a 1.5 Mt/y direct shipping iron ore operation, says it is working with both parties to finalise the detailed scope of services, schedules and formal contractual terms of engagement.

Dynamic, who worked with Strike to plan, licence and develop magazine and explosives storage facilities for the project in consultation with the Department of Mines, Industry, Regulation and Safety (DMIRS), said the contract is estimated to have a four-year initial term.

On top of this, Strike said the final objection on its proposed haulage road, Miscellaneous Licence (ML) L47/934, has now been withdrawn after the execution of an Access Deed with the underlying tenement holder. With the execution of this deed, the last outstanding ML related to Paulsens East is expected to be granted by DMIRS during the next two-to-four weeks.

“Once L47/934 is granted, and subject to DMIRS having no further issues with any technical or environmental aspects of the Mining Proposal, DMIRS is expected to approve the Mining Proposal for Paulsens East shortly thereafter,” the company said.

Strike also recently made an investment in acquiring a second-hand ore sorter, ancillary materials handling and control room equipment, together with conveyors that were recently sold at auction, resulting in a significant saving in project capital costs at Paulsens East.

“Strike is planning to use specialised ore sorters as part of its processing flowsheet, to assist with the optimisation of the production of high-grade lump ore from the mine,” it said. “To deliver the required throughput for the mine, a total of up to three ore sorters will be required.”

Further long-lead items secured include an order for 13 Ultra Quad Road Trains (comprising 13 prime movers and 52 trailers) for exclusive use on Paulsens East.

On the communications side, Strike has now entered into a contract with Telstra to commence works on establishing suitable communications infrastructure for the mine site and village. Due to the remote location, a dedicated microwave tower on site is required together with associated voice and data equipment. The construction of the tower and provisioning of the service will be critical for safe and effective communications during the construction and operational phase of the mine.

William Johnson, Managing Director for Strike, said: “With Campbells Transport already selected as its preferred haulage contractor, the company has now selected all of its key contractors for Paulsens East. The securing of further long lead time items together with the ore sorter and associated equipment are important steps as the company advances towards making a final investment decision on Paulsens East.”

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