Deconstructing ECS

Today's eddy current separator (ECS) technology is ideal for scrap recyclers, MRFs and other recycling facilities that want to automate recovery of nonferrous metals (after ferrous recovery) from MSW, sand, glass, dirt, CTD, electronic scrap, shredded automobiles and refuse. 

Eddy currents, also called Foucault currents after French physicist Léon Foucault (who is generally credited with having discovered them in 1855) are electric currents induced in conductors when a conductor is exposed to a changing magnetic field. Due to relative motion of the field source and conductor, or due to variations of the field with time, this causes a circulating flow of electrons, or current, within the body of the conductor. These circulating eddies of current have inductance and thus induce magnetic fields, causing repulsive and attractive forces. 

According to Pennsylvania-based Eriez Manufacturing, they were granted the initial patent for the eddy current separator, as we know it today, in 1969. In 1987, another leader in the field of ECS, Steinert, based out of Germany, originated the eccentric pole eddy current separator.

Recycling Product News talked to experts from both Eriez and SteinertUS, as well as the U.K.'s Steelweld Enviro Products and Michigan-based Industrial Magnetics, to find out more about the evolution of the eddy current separator, current models available, trends to come, and what to think about when considering adding or updating this technology in a recycling application.

Evolving Technology
According to Robert Broughton, scrap market manager, SteinertUS, eddy current technology has been constantly revised and improved upon as the methods of  material preparation and presentation to machines has evolved.  

"The evolution of nonferrous recovery has grown from being a small piece of available revenue streams to the main driver in many instances with different material feedstocks," said Broughton. "With this change in feedstocks, and a change in the economic model for many of the industries that we serve, we have continued to make changes to maximize the three main variables in ECS: throughput, recovery and purity." 

Broughton said that some of the most meaningful change in ECS technology, for any application, from ELV to WEEE recycling, has been in the design of the magnetic system, in many cases optimized for smaller and smaller particle processing.

"Many times the new goal is not only getting the traditional nonferrous recovered, like aluminum and copper, but more and more, a strong emphasis is placed on the recovery of precious metals from these streams," he said. 

Over the last few years Broughton notes that they have seen a tremendous change in how clients buy, process and sell their products. "Looking back only a few years, China's ‘Green Fence' initiative caused a large market disruption. Currently ‘National Sword 2017' (and Chinese import restrictions) are having similar effects. Steinert is still looking at the end goals of cleaner product, closer to a furnace-ready state." 

He added that their company is also committed to the success of changing economic models that have occurred at MRFs over the last several years. "Our CanMaster product line offers a compact footprint and rotor designed specifically for the recovery of aluminum cans," he said. "We have even designed small modifications to reduce the potential contamination of plastic films in MRF aluminum cans."

Chris Ramsdell is product manager in Eriez' Recycling Group. He said the company has been designing, manufacturing and selling eddy current separators for almost 50 years.  
Today, the company carries a broad ECS product line, and over the years, has supplied eddy current separators for dozens of different recycling applications, ranging from ASR processing to e-scrap, and PET flake to waste-to-energy bottom ash. 

"ECS Technology has improved drastically in recent years," said Ramsdell. "The target has been to design machines that can maximize the recovery of smaller and smaller nonferrous metals that previously went unrecovered."  

He stressed that the changing waste stream in MRFs has been a contributing factor to new equipment developments in the industry.

"Eriez' development and standardization on an eccentric eddy current rotor has allowed our MRF ECS units to become more tolerable of ferrous metals and more robust to handle higher throughput capacities, while maintaining the same great separation performance," he said. "Our latest ECS technology will reliably recover UBCs with 99 percent efficiency, at a significantly lower installed cost for the MRF."

Earlier this year, Industrial Magnetics, Inc. (IMI) based in Michigan, acquired Javelin Manufacturing, an ECS manufacturer  based in Indiana. (See news, page 10 of this issue.) IMI's chief business development officer, Dennis O'Leary, said that as the magnet supplier for Javelin since 2010, they have been fortunate to gain a view of the markets and technological evolution in ECS through their lens.

"There have been large strides made in terms of magnetic geometry, magnet strength, rotational speeds and unit widths and belt speeds," he said. "One obvious initiative and push in ECS development currently is the fines recovery unit." 

O'Leary also noted that he attributes all of these developments to the need to meet requirements presented by an ever-changing and growing waste stream in all sectors. 
Steelweld Fabrications, based in the U.K., has been working for over 30 years as a sub-contractor supplying welded and assembled components to the crushing and screening industry. Due to legislative demands in the recycling industry over the last decade, the company decided to design and manufacture their own range of products under the subsidiary Steelweld Enviro. The company's first offering, introduced in 2016, is a portable (track-mounted) eddy current separator.

"The technological advances seen by eddy current separators have greatly increased throughput capacity while maintaining a high level of separation across a range of applications," said Andrew Mackle, senior engineer, Steelweld Enviro.

 "Over the last few years we've seen ECS systems becoming more compact requiring less power to run, yet becoming more powerful with respect to separation. The first machine in our range is a portable eddy current separator - the Strobe ECS 1500."

The latest models
"Our Strobe 1500 allows for 3-product separation - ferrous metals, nonferrous metals and non-metallics," continued Steelweld Enviro's Andrew Mackle. "The feed speed of material over the eddy current drum and the speed of the eddy drum are variable, to cope with a range of product types, and the unit can be powered by an on-board 65-kVA generator or plugged into mains electricity. It also features low-pressure crawler tracks so it can be used on softer terrain."

He said they have created a complete ECS system on tracks, including discharge conveyors and on-board power.

"Our design brief was to build a reliable portable ECS that allows the customer the freedom to bring the Strobe 1500 to the material, unlike static ECS applications where the material must be brought to the unit to be processed," continued Mackle.  

"The fact that the unit is fully portable allows the customer to separate various material types that they might not have considered before, rather than having the ECS in a fixed recycling plant with a single waste stream."

Eriez' latest model eddy current separator was designed for very fine (-1/4-inch) sized material. According to Chris Ramsdell, the model UHF (Ultra High Frequency) ECS is a high-strength and high-frequency machine designed so that, when material is sized properly, customers can reliably recover bare copper wire and microfine cast aluminum. "We've found that, with our UHF ECS, ASR processors, for example, are recovering an additional three to five percent of additional fine zorba that had previously been sent to landfill," he said. 

IMI's Dennis O'Leary said their initial product offering started with an over-2-inch particle size removal and an under 1-1/2-inch particle size recovery unit. They then moved on to a stronger, higher-polarity unit designed for material that can be used "across the board," from +5-inch to < 3/8-inch particle sizes. "As we move forward we will continue to develop product that flanks our existing technology and will give the customer the most marketable product," said O'Leary. "We want to be seen as a strategic partner who brings value, versus a parts supplier."

SteinertUS' Robert Broughton said Steinert has never waivered on their commitment to improve the performance of eddy current separators, continually evolving the product line to match a variety of different separation tasks. He said Steinert's innovation in this space has recently yielded several new product lines, most significantly development in the microfines and <5mm areas. 

"Steinert's new EddyC Fines is specially developed for recovering fine nonferrous metals and incorporates a number of innovations from magnetic design, splitter adjustment capabilities and maintenance-friendly options, including a 10 minute belt-change frame design," he said.  

Buyer considerations
Chris Ramsdell pointed out that two of the most important elements for a recycling operation to consider, when thinking about adding ECS technology, are the percentage of recoverable nonferrous metals in the material to be processed, and/or material grade improvement.

"This is information that we're able to supply to the customer prior to them making a purchasing decision," he said.   "Eriez Magnetics offers material testing services at our Central Test Lab in Erie, Pennsylvania. We're able to supply magnetic separation and eddy current separation testing depending on the application requirements. At the conclusion of the testing, Eriez will furnish a complete test report which includes weight splits, material yields and high resolution photos of the separated materials."  Buyers should make sure they do their research and find out which waste streams an ECS is best suited to, said Steelweld Enviro's Andrew Mackle. Static vs. mobile configurations should also be considered.

"Complete static eddy current systems can be expensive to design and install, only to find out they're not giving the end product as required," he said. "This is where the Strobe 1500 has a huge advantage." Because it is mobile, "it does not tie down a customer to a single material type. 

"It's also important that time is spent so the system is set up correctly," he continued, adding that existing equipment is another important consideration. Buyers should consider what equipment they have in hand, and how it might help maximize results when used in tandem with an ECS.

"Better results may be achieved with additional processes in place, before feeding any material onto the ECS," added Mackle. This can be achieved with shredding and screening equipment, and "by having an even bed height of material passing over the eddy current drum, via a vibrating pan feeder."

Steinert's Broughton advises his buyers to look for eddy current separators that are specifically matched to the size and makeup of the material to be recovered, and for machines with excellent reliability and serviceability. 

He said the next most important variable to understand is ensuring that the capacity of the eddy current is not exceeded and to purchase the correct width unit to maximize results. 

"In the past, eddy currents were sometimes only used to recover the ‘cream of the milk' as quickly as possible," he said. "With the new economics of large-scale recycling, every percentage point of metallic value is essential to the profitability, or lack thereof, of the enterprise."

According to IMI's O'Leary, when purchasing an eddy current or magnet, one of the most important considerations is the customer's comfort level with the company and staff supplying and supporting the equipment. 

Questions buyers should ask include: "Is the company leading us to the equipment that will solve our problem or selling what they have to sell? Are they going to be around when we need them? Will they take care of any problems that may arise? Do they keep spare parts on the shelf and are they reasonable priced?" "Eddy current technology, in and of itself, is fairly basic," said O'Leary. "You can buy a great piece of equipment and then rue the day you bought it if you can't get help when you need it."

Changing materials, Artificial Intelligence and new profitability
Going forward, Steelweld Enviro points to the biomass and waste-to-energy sectors as ones to watch for growth in applications of ECS technology."In the U.K. we're seeing a higher level of separation requirements, especially in the wood and waste biomass industry," said Mackle. "In these applications there must be zero metallic presence before the material enters the burners to generate electricity. With renewable energy on the increase, there is more demand for ECS systems to cope with organic biomass fuels."

He continued, "With many countries adapting to renewable energy, there will be an increase in demand of a clean biomass product. The Strobe 1500 reduces the amount of manual labour required with a consistent and repeatable level of clean material that is separated into three individually defined stockpiles."  

Eriez' Chris Ramsdell said a trend they are noticing in the MRF equipment sector currently is the increase in AQC (autonomous quality control) technology being introduced to the market, adding that ECS will play a role in any new MRF landscape.

"The Max-AI technology now offered by NRT uses vision systems and artificial intelligence to identify each item and a robotic arm to lift and sort each piece of material to its proper location," he said. "This equipment is reducing the need for manual pickers even with a more heterogeneous material stream." 

By installing an ECS upstream of AQC and artificially intelligent sorters, recyclers "can greatly reduce the burden of material that these systems are required to sort," he said. According to Steinert's Broughton, over the coming months and years ahead, there will be a continued focus on fines and microfine particles in the eddy current separator sector. "We describe these particles in several different ways, but historically, much of the value in material streams (<5mm) have gone to waste or landfill," he said. "These streams can be substantial revenue adders and do not involve changing current inbound material costs.  

"Many new separators are generating new money or new revenue streams for operations," continued Broughton. "This can significantly increase profitability or competitiveness within a region." 

One final trend going forward, said Broughton, has to do with the need for the industry as a whole to adapt to an ever-restrictive and demanding end user marketplace. "Product metallic purity is very important, but long-term, moving from a mixed metal stream to furnace-ready base metals is the trend," he said. "Eddy currents, along with X-ray or other refinement technologies are critical to ensure access to this market and optimal material values."  RPN

This article was originally published in Recycling Product News, October 2017, Volume 25, Number 7.