Faced with a flood of cheap Chinese imports, the steel industry has been making mainstream headlines over recent months in both Europe and the US. With prices dropping significantly the industry has been hit hard, as have some in the scrap metal sector.
However, according to a recent report, over the next five years annual revenues for the global metal recycling market are expected to grow at a Compound Annual Growth Rate of 7.95% from $277.12 billion in 2015 to $406.16 billion by 2020. In short - the scrap metal industry is a huge and highly competitive industry.
To succeed in such a fierce market having the right equipment for the job can give an operator a real competitive advantage. With it’s central importance to scrap metal processing, this is especially true of shredders. But with so many different waste streams being processed by different scrap metal recyclers, and numerous end product specifications required, what are the key factors operators need to consider?
“When you’re looking to shred metals as opposed to RDF or MSW, typically you need either a four or a two shaft shredder,” explains industrial shredding specialist, UNTHA’s Gary Moore. “You need a degree of intrinsic strength in the machine to take the heavier product. You need a slow speed, high torque machine.”
“You need to understand not only the metal being processed, but also the throughput and the product sizing,” he tells WMW. “Say you’re shredding aluminium engine blocks and you need to achieve a <100mm product size for re-smelting you’d use a four shaft shredder with a power range of 150 kW to 300 kW. If you’ve got no particular requirement for product size and the material just needs to be volume reduced, you’d use a two shaft shredder.”
Horses for Courses
According to Moore there’s currently strong demand non-ferrous aluminium applications, as well as for equipment to process Waste Electrical and Electronic Equipment (WEEE).
“For about the last six years we’ve seen a big growth from WEEE scrap,” he says. “And that WEEE scrap is in two formats – IT and technology based scrap such as computers, and domestic appliances such as vacuum cleaners, microwaves and toasters.”
For larger domestic appliances Moore says that the best setup is to have a two shaft shredder to pre-shred the material and reduce the bulk, and then run it through a four shaft machine to not only produce the required size, but to liberate the different materials. Once the two shredding stages are complete the material is passed through an overband ferrous extraction system and an Eddy Current Separator (ECS) to recover non-ferrous metals such as aluminium and copper.
“What we’re doing is producing a ferrous pile, a non-ferrous pile and typically a plastics pile, which may be further sorted downstream. We’re pretty much converting all of the waste material back into a usable product,” he continues.
However, according to Moore when it comes to selecting the best setup for a more mixed stream of waste metals it’s important to understand the individual requirements of the operator and the type of materials they are handling.
“It’s a completely different take,” he says. “The application is very different so we have to have a discovery meeting to find out exactly what they do. When you go to a scrap yard they could be processing car body panels - or all sorts of other items. Because they’re handling a different type of waste, inherently the machines get larger and larger.”
The Unshreddables
While some applications will see a very homogenous or predictable waste stream being processed, in others rogue items beyond the shredder’s capability to break down can get into the machine, for example a cast con rod from a large marine diesel engine. However, on models such as UNTHA’s new RS150, automatic overload protection systems are fitted to step in and stop the machine.
“The machine will sense that there’s an amperage load build up and will sense too much current is being drawn,” explains Moore. “The machine will then stop and reverse to take the load off. Some of our machines have two or three reverse cycle because it may just be a general overload where it’s been over filled and it can often clear itself.”
However, he adds that it’s also important to follow health and safety procedures when operating such machines. There should be an exclusion area around the machine and the grab operator filling the hopper must be vigilant for items which should not be there, such as gas cylinders - which if punctured can be lethal.
Maintenance
The maintenance regime on metal shredders is somewhat less frequent than for their single shaft, high speed siblings used to process MSW and fuels.
“With our low speed, high torque machines the maintenance routines are typically two or three times a year,” explains Moore. “We tend to check the torque on the end bearings and make sure that the cutters don’t become loose in the cutting area. The cutter sets themselves can be removed, rebuilt and used again and again.”
“We also check things like the drive systems to make sure the motors are working properly and pulling the correct temperature, as well as the overload sensors to make sure they are functioning,” he ads.
Innovation
Shredder technology has made some significant advances over recent years. One good example is UNTHA’s Torque Drive system - a flexible drive package which makes use of inverter driven, variable speed synchronous drive motors to increase efficiency. This allows the machine to slow down and increase its torque when it encounters tough to shred material.
According to Moore one of the most sought after developments UNTHA has been working on is a fire detection and suppression system for its latest machines. The adoption of fire prevention system is being increasingly encouraged by insurers with the carrot of reduced premiums for the operator
“What we’re doing with a lot of our machines now is installing factory fitted systems to detect heat build-up at the relevant key points on the shredder,” says Moore. “Before it gets to the point of having a flame or a fire growing we’ll be able to detect it, whether it’s heat generation or spark generation, and we can douse it. It protects not only the shredder, but also the discharge conveyer.”
Moore concludes that as technology advances these type innovations will be refined and efficiency and capability will improve. But it won’t change the importance of selecting the best shredder for your application.
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