By wearfacing their equipment, recycling businesses can substantially reduce their costs, both financial and environmental. Inaki Ezpeleta, the Global Business Development Manager for Recycling at Castolin Eutectic, discusses the principal wear-related challenges and the available advanced wear management solutions.
The legislative and public demand for increased recycling initiatives is intensifying. The majority of people are aware that discarding used products is a misuse of natural resources. In addition, they recognize that the production of replacements for discarded items necessitates an increase in energy consumption and CO2 emissions. When the manufacturing process begins with virgin materials as opposed to recycled ones, these expenses are amplified.By wearfacing their equipment, recycling businesses can substantially reduce their costs, both financial and environmental. Inaki Ezpeleta, the Global Business Development Manager for Recycling at Castolin Eutectic, discusses the principal wear-related challenges and the available advanced wear management solutions.
Difficult market conditions
Recycling is fundamental to sustainability, but to be viable as a business activity it needs to make a profit. That can be difficult for various reasons. One is the wildly fluctuating value of recycled materials. The price of copper or aluminium, for example, can drop suddenly, making its recycling less profitable or even non-viable.
Increasing energy prices are also eating into the sector’s profits. Reducing consumption has become vital to staying in profit, as well as meeting increasingly stringent carbon emission targets.
A further difficulty is the recycling market’s complexity and rapid change. New materials, processes and technologies require constant investment in expensive equipment, which adds to capital and maintenance costs.
Heavy duty and harsh forces
To understand how wearfacing addresses these problems, we must first look at the nature, function and operating conditions of machinery. Although recycling is a complex, multi-segmented industry, there are common processes which apply to each specialised area. These include:
- Collection of materials and transport to the recycling site
- Transport/movement of materials within the site
- Crushing and/or shredding to the size required for the next process
- Sorting into different material streams
- Further processing – including refining
- Supply of recycled raw material to manufacturers/users in the condition required.
In each activity, contact between materials and equipment results in wear and damage – especially at the contacting surfaces. The wearing and damaging forces include abrasion, erosion, impact, fatigue and vibration stress.
The true cost of wear
Replacement of worn parts is costly. Managers must consider not only the price of the new part but the cost of labour to fit it and the loss of income while the machine is out of action. Lost output is even higher in the case of unplanned downtime due to failure of a worn component during operation.
In key components such as the cutting elements in shredding machines, wear can also lead to inefficiency. A worn cutting edge is less effective, so material may have to be fed through the shredder more than once to reduce it to the required size. That means extra running time, energy consumption and wear for the machine, and extra labour to operate and feed it.
In some equipment, a worn blade must be applied with more force – and a higher energy cost – than one in sharp condition. In each case, consuming more energy adds to carbon emissions as well as power bills.
Castolin Eutectic wear protection treatments are the answer
All these costs can be reduced by extending component life through wearfacing – or hardfacing as it is sometimes known. Protective treatments can be applied to surfaces during original manufacture or assembly of the equipment. They can also be retrofitted as part of a repair, which restores and improves the component, giving it a second life and a better-protected and longer service life.
Although similar machinery and processes may be found across the spectrum of recycling operations, each presents a different set of conditions and needs. Variable factors include the types of materials handled, as well as wear patterns, pressures, temperatures and presence of corrosive substances.
This creates a variety of wear problems that can be solved by a wide range of wearfacing technologies and products. Each of which can be modified – in terms of structure and composition – to meet specific requirements. No two jobs are the same.
A variety of materials
Today, the main recyclable material segments are:
- Ferrous metals
- Non-ferrous metals
- Tyres and rubber
- Electronic scrap.
While hard materials like metal may seem especially challenging, even soft substances such as paper have substantial wearing effects on equipment. The same is true for household plastics, whereas ground glass is particularly abrasive, and every other recyclable material also has its own unique properties and demands.
Demanding processes and equipment
Collection vehicles and containers are often the first surfaces exposed to recyclables and their wearing effects. At the recycling plant, grapples, dumpers, grab trucks, bulldozers and conveyors move materials between processes. Each is vulnerable to wear and abrasion from the materials. The same is true for feeder chutes, hoppers, pumps and pipework through which materials pass.
Crushing and shredding machines typically feature rotating shafts armed with cutting discs, blades, knives, teeth or hammers. Not surprisingly, these can very quickly become blunt and worn out of shape. In addition to harsh abrasion and constant heavy impacts, the machines are subjected to strong vibration forces.
Vibration may also be a factor in sorting processes, especially where vibrating conveyors are used. Along with relatively simple sorting using screens of different sizes, there are more sophisticated methods. They include magnetic drums for ferrous metals, eddy currents for non-ferrous metals, cyclone separators for dust removal, laser techniques which separate materials by colour, and use of X-rays or flotation tanks for separation according to density. These technologies require expensive equipment which needs to be maintained and protected.
After sorting, there may be further processes. For example, grinding is used in glass recycling to reduce the granules to a regular size. These are then mixed with other ingredients before moving to the glass-making furnace. Glass grinding and mixing machines face powerful abrasive and erosive effects from these materials.
Comprehensive wear management solutions
For many of the equipment surfaces described, a simple protective approach is to line them with steel CDP wear plates. These are hardened with alloys and can be applied, for instance, to line bulldozer and grab buckets, conveyor sides, chutes and any other containment or transport surface in the recycling plant.
Highly resistant to abrasion, impact and vibration, these types of wear plate typically last five times longer than OEM linings. They can be easily cut, shaped and fitted to protect any surface with screws, rivets or spot welding. Where required, plates can be supplied as standard plates or as pre-cut and formed sections matched to the equipment’s size and shape. This latter point is particularly important when lining the cylindrical or conical parts of a cyclone, or the inner surfaces of glass crushing, grinding and mixing machines.
A range of wear plates, wearfacings and coating variants exist for different circumstances, with the optimum choice depending on the materials being processed and the forces at play.
Pipework requires another ready-made solution in the form of tube sections, elbows and Y-joints with alloy-reinforced lining. Known as CastoTubes, various diameters and section lengths are available, and assembly is simple.
When it comes to the crushing and cutting elements of crushers and shredders, a range of alloy and polymer wearfacing coatings (called MeCaTec at Castolin Eutectic) and welding wires can be applied to reinforce surfaces. Ideally, they should be applied from new, as a preventive measure, but in some cases they can be used in repair and restoration.
In some cases, the original shape and sharpness of a cutting surface can be restored. However, for large hammers which have lost many kilograms of metal through wear, replacement of such a heavy loss by welding is uneconomic. Here, it is important to increase the life of the replacement hammers by applying a wearfacing preventive treatment. In comparison tests, where customers have agreed to allow treatment of one hammer, the difference in durability very soon becomes obvious.
Wearfacings can be used to reinforce and protect grapples, which suffer aggressive wear from metal-to-metal contact and shocks. Ceramic surfacing polymers also have multiple uses in protecting valuable equipment.
The Castolin Eutectic reliability engineers always ready to help
Specialist wearfacing products can be bought for use by a customer’s own engineers or applied by the company’s field engineers, who can also be called on for advice, assessment of wear problems, recommendation of solutions, and training around the world. It’s even possible to compare alternative solutions using Castolin Eutectic’s EcoTest calculator, which shows the savings in cost, and CO2 emissions for proposed wear protection solutions. This type of advice from suppliers often becomes more valuable over time as the external experts become familiar with the equipment and its health and maintenance history.
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