Conveying systems suppliers are launching new solutions to help users reduce downtime, increase flexibility and mitigate dust emissions and spillage problems
Conveyor belts for handling bulk materials have to function in extreme conditions. The climate can be hostile, from freezing to scorching hot and/or humid. Moreover, the materials to be conveyed are usually abrasive and heavy.
Occasional belt wear and tear, and the consequent downtime needed to replace worn sections, is accepted as part and parcel of the business. But suppliers are constantly looking for ways to strengthen conveyor belts and at least lengthen the periods between downtimes, even if eradicating them remains a distant dream.
Fenner Dunlop, which is now part of the Michelin group, says that its KordFlex product has the highest strength-to-weight ratio of all its conveyor belt reinforcements, with more than double those of synthetic fabrics such as polyester and nylon, and five times that of steel.
KordFlex is made from aramid fibres, a class of heat-resistant and strong synthetic fibres. They are used in aerospace and military applications, for ballistic-rated body armour fabric and ballistic composites, in bicycle tyres, marine cordage, marine hull reinforcement, and as an asbestos substitute. Kevlar is perhaps the best known para-aramid fibre on the market.
The name is a portmanteau of ‘aromatic polyamide’. The chain molecules in the fibres are highly oriented along the fibre axis. As a result, a higher proportion of the chemical bond contributes more to fibre strength than in many other synthetic fibres.
Fenner Dunlop recently installed a KordFlex conveying system for an iron ore company operating in Australia’s Pilbara region, to extend the belt life.
Reducing belt downtime was a priority for the miner. It had recently extended the shutdown frequency. However, its 28/7 covered steel cord belt construction fell short of its historical two shut rotation change-out target.
The company’s lifecycle had seen some improvement by increasing cover thickness on traditional steel cord construction, but an increased need to reduce shutdown frequency meant that, eventually, the belt reached a point where the machine had surpassed the original equipment manufacturer’s design capacity.
ECS team deployed
Fenner Dunlop sent its engineered conveyor solutions (ECS) team to help the client. The team began a trial of compound changes. However, the thickness of the belt was restricted, meaning no additional weight could be added, or the belt would become unbalanced.
To address this problem, the team opted for KordFlex, which is a high-tensile aramid fabric carcass. The material results in a significant weight reduction that means additional weight could be used for the top cover compound to improve its wear resistance.
By changing the material, Fenner Dunlop was able to increase the belt from a standard 28mm top cover and 7mm bottom cover to 32 mm and 8mm, respectively.
According to Fenner Dunlop, the additional 4mm on the top cover significantly improved the lifespan of the belt by around 15% to meet the shutdown requirements.
Jimmy Lindgren, ECS manager at Fenner Dunlop, said that using a lightweight, high-strength carcass design permitted the advantageous additional cover gauge that was required to extend the belt life.
“Additionally, this belt was locally made in our manufacturing plant in Kwinana, so it gave the client assurance that the quality was going to be according to Australian Standards, and we could guarantee quick delivery, not to mention allowing the opportunity for the client to visit the factory and see the belt being made,” explained Lindgren.
As part of the trial, the ECS team also used Fenner Dunlop’s Ultra Tuff abrasion-resistant conveyor belt compound as the top cover. With a typical abrasion resistance of 20 mm3 , Ultra Tuff has been specifically designed for systems handling high-abrasion materials.
“One of the key drivers to the KordFlex success was the highly specialised method of joining the conveyor belt together,” said Lindgren. “KordFlex adopts a single ply construction, and hence traditional methods of joining were not applicable.”
KordFlex also uses a high-intensity splice (HIS) design, allowing for singleply constructed belting to be joined using a vulcanised platen.
“This is the first of its kind to be successfully installed in the Pilbara on a high-tension balance machine, and was conducted by Fenner Dunlop’s elite service team that has years of experience in such HIS methods of joining belt,” added Lindgren.
KordFlex can be used on systems with a smaller pulley diameter, creating a lighter-weight belt that can result in greater energy savings per tonne conveyed.
Fenner Dunlop performed the installation and commissioning of the belt, ongoing inspection and monitoring, performance optimisation and data collection.
The company says the trial has helped showcase its ability to install an aramid fabric belt on a high-tension balance machine, one of the first of its kind with the ability to extend belt life in the right application.
In July last year, Fenner Dunlop was also awarded a permanent contract by Rio Tinto Ports to provide conveyor maintenance services in Western Australia.
The long-term arrangement will see Fenner Dunlop service all the conveyors at Cape Lambert and Dampier Port, which together represent a significant portion of conveyors in the whole of Australia. To support the customer, a new Fenner Dunlop branch opened in nearby Karratha. COO Steve Abbott said that the contract should create more than 40 full-time jobs.
Pick and place
Having a large-scale fixed conveyor system is advantageous in big mines and pit-to-port applications. However, some applications do not call for a permanent, long-distance overland installation.
Last year, Fortescue Metals Group (FMG) commissioned a relocatable conveyor at its Cloudbreak ore processing facility (OPF) in the Pilbara.
The 5 km conveyor includes a semi-mobile primary crushing station, and feeds directly into the Cloudbreak OPF. The relocatable conveyor and semi-mobile crushing facilities can be positioned close to pits, and relocated once they are mined.
By providing greater flexibility and increased accessibility to remote mine pits, the relocatable conveyor will reduce haulage costs, offsetting rising strip ratios and delivering sustained efficiency improvements across the business, said FMG.
Also in Australia, Nepean Conveyors is introducing its relocatable conveyor system this year.
The conveyor has taken more than two years of research and design to develop, and Nepean claims it promises to upend the conventional approach to conveyor design because of its improved mobility, operational flexibility, ease of transport and speed of installation.
Instead of building parts to meet the needs of ISO container dimensions, the Australian and international patents-pending Nepean conveyor is itself a half-height high cube portal frame with the same length as a 40ft container that is certified for standard freight shipping.
This means the conveyor is transportable anywhere in the world as a fully assembled unit.
Not only does this approach allow the conveyor modules to be stacked and loaded for direct transport via sea, rail or road, but it also makes the conveyors easier to move, remove, assemble and eventually disassemble as the site requires.
The belts are carried inside the frame and can be up to 1,800mm on straight conveyors and 1,600mm on curved conveyors. Roofmounted wind guards are also available for each module in a single curve or straight two-piece configuration.
The modules can be triple stacked on a prime mover and unloaded in one bundle using standard container handling equipment, such as lift trucks or reach stackers, which can then place each module in line for final connection.
This approach vastly reduces the total install cost per lineal metre by minimising both time and staff requirements during set-up.
“One of the areas we really wanted to target was logistics,” said Bill Munday, Nepean’s general manager, New South Wales.
“It can turn into a real logistical exercise moving all this equipment from one site to the next and doing so efficiently. The beauty of having a half-height high cube container format is that they can be multi-stacked on ships, trains or trucks. You can potentially get nine modules per road train at a length of 12m per module.”
The unit also minimises ground works. The frame’s integral legs can be set in place by removing a pin, folding them out, and replacing the pin to lock the legs in position.
The foot plates also have holes in them for additional stakes to be inserted, which adds stability and security in cyclone-prone zones. While the exposed design of the frame means the unit lacks the surface area to be blown over, it could still slide sideways, so the stakes help to eliminate this issue.
Once the modules are aligned to an installation jig on the ground, which is adjustable for idler spacing and roller configurations, the structure can be elevated by up to seven degrees and banked around corners.
Alternatively, ground screws are also available for added stability and flexibility. Trestles with independent walkways can also be assembled using these ground screw bases to build the conveyor over watercourses or cattle crossings. These options allow for the conveyor pathway to be roughly graded within 100mm.
“All the equipment is pre-designed for a fully functioning conveyor, and the container module is just part of the system,” added Munday.
We have also designed a one-piece head end that incorporates a drive system up to 4,000 kW, a loop take-up and delivery jib that can be put on a 200t float to transport around mine sites. It is held in place by large ground anchors – there’s minimal concreting or civil works – you just dig a couple of holes and bury the ground anchor.”
The conveyor is not classified as fixed plant, due to the way it has been designed. In addition to reducing civil works and installation costs, the conveyor’s mobility allows it to be adaptable to changes in mining operations, and positions it as an alternative to mine trucks when it is time to move the conveyor on-site.
“If you put in a traditional system over a five-year period, that’s classed as fixed plant and depreciates over those five years,” Munday explained. “With this type of equipment, because it’s modular and reusable, it’s got a 20-year lifespan, so you can depreciate it over a much longer period. It’s not classed as fixed plant for that reason.”
In some cases, conveyor belts are prone to product overflows and dust emissions. However, French company Standards Industrie claims that its Liftube covered system, can greatly reduce operating losses, dust emissions and maintenance.
The system, which is suitable for transporting high-temperature products, is equipped with self-extinguishing edges and accessories that can resist temperatures up to 300 degC. It is ATEX-certified with a three-year warranty.
Liftube seals a conveyor belt by covering it with hoods. In this way, Standard Industrie says it reduces product loss and cleaning requirements during the transport of products such as sand, limestone, clinker, aggregates, grain and flour, as well as being suitable for mining, recycling or wood treatment factories. The system enables the belt to run on a central horizontal tilting roller and to slide on the edges, which also tilt.
A removable hood can be adapted to the equipment to reduce dust emission. Only the size of the hood and the central horizontal roller depend on the width of the conveyor. The conveyor belt and rollers can also be easily accessed thanks to innovative tilting glide-boards.
The dust-collector is a 2m kit with a filtering unit atop the hood. Standard says it is suitable for belt widths of 500mm to 1,400mm, and speeds of 0.05 to 5 m/sec.
A Liftube system was recently installed at a platinum factory in South Africa. The customer was facing a daily loss of 2-3t of material on the mill feeding conveyor. This required putting in place significant resources for cleaning – as much as four to six hours each day carried out by four to six people. The consequences were wasted time and money, as well as disruption in the production process.
So, 30m of Liftube were installed with a belt width of 900mm to fit to the dimensions of the conveyor. An inspection hatch was installed on one of the covers so that the customer can control the routing of the product to the mill.
According to Standard Industrie, the customer has improved productivity and it is no longer necessary to use a team to clean the area.
In another installation, a limestone quarry in the Haute-Savoie region of France wanted to integrate the Liftube system and the dust collector into a new project that included conveyors, hammers, and grinders.
The length of the conveyor is 27m at the centre distance for a belt width of 800mm, a hopper hood, and a dust collector. The conveyor is located just under the crusher, which creates a dusty airflow between the feed hopper and the chute. The speed of the belt pushes this charged air into the conveyor, and can create dust emissions at the outlet.
To solve the problem, several solutions were available – installation of decompression chambers, a misting system, vacuuming, and dedusting.
The last solution, which was chosen by the customer, is the most compact and the economical. Fixed on only 2m of Liftube, the dust collector is installed after the last chute, and captures the depression created by the fan particles in suspension. The multi- pocket filter retains these particles, which fall back on the belt during automatic unclogging cycles.