Equipment and Services: Advanced Downstream Separation

Jul 18, 2017, 16:49 PM
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July-August 2017

Downstream separation systems for recovering nonferrous metals and stainless steel—and removing contaminants—are getting sleek upgrades to capture and segregate material that was once thought to be out of reach.

By Megan Quinn

As scrap separation technology gets better and better, customers demand more sophisticated, more precise sorters that can get out all the metal from a stream—and they mean all the metal.

Graphic-for-Equipment-Focus_SeparatorsConsumers want machines that will recover fines smaller than 10 mm, plus machines that will further sort grades such as Zurik into separate copper, aluminum, and other metal streams in order to sell them directly to a domestic smelter rather than risk shipping internationally. Customers want to keep their options open, too: When purchasing a new sorter, whether it’s an eddy-current nonferrous separator, a sensor sorter, or a stainless steel separator, processors are asking for the flexibility to keep up with changing markets, manufacturers say.

The finer points

An estimated 30 to 40 percent of shredded nonferrous residue is considered fines, or pieces under 20 mm in diameter, according to a managing director for a Florida magnet and sensor-sorting company. That’s one reason manufacturers see the value of upgrading and tweaking their sorters to more effectively target fines. Such technology has “come a long way in the last decade,” adds the scrap market manager of a German magnet and sensor-sorting company with North American operations based in Kentucky. Eddy-current separators are often the first downstream separation tools to get the upgrades that make it possible to sort tinier and tinier pieces, he says.

One Pennsylvania manufacturer says its newest eddy-current separator uses high gauss at the belt’s surface “with a large number of magnetic poles” to improve Zorba recovery, even fines as small as 2 to 3 mm, without additional sensor or optical sorting equipment afterward. Other companies have decided to think small, too. The Kentucky sorter company introduced a new ECS in April that targets fines under 10 mm—a machine customers requested because “they wanted to work with finer material,” says the company’s North American president. The new model operates at 4,000 rpm, the same as previous models, but it now is more precise in liberating tiny fines. “With eddy currents, the finer the material, the less it jumps because it doesn’t have as much surface area,” he says. Another upgrade is the splitter. The company’s older ECS model had a splitter that could be adjusted along two axes, but the new model’s splitter can be hand-adjusted both horizontally and vertically down to the millimeter “however you want” to recover and sort fines, he says.

A new company based in Utah has developed a solid-state eddy-current separator. Instead of permanent magnets on a rotating drum, the new machine uses an electromagnet to separate nonferrous fines. “With a conventional eddy-current separator, you can pull nonferrous from plastic or glass, but it’s much more difficult to separate different types—for example, copper from aluminum” or different types of aluminum alloys from each other, says the company’s co-founder. The new technology uses much higher frequencies than a typical eddy current, he says. Since different metals have a different resistance to the electric current, an operator can tune the frequency to optimize for a particular type of separation without using optical or density sorters, he says. “This is one of the only technologies out there that can do that in these very small fines sizes” of 1 to 5 mm, he says. The company is working on other versions that can separate larger pieces of metal, too.

An Ohio-based recycling equipment company aims to get even more Zorba or copper out of a stream by separating pieces as small as 1 mm from dirt and fluff left over after ASR goes through an eddy-current separator. The company’s multi-step, patent-pending fines plant uses a series of screens, air separators, and density tables to separate light and heavy metals and remove wood and plastic. The material then goes through another proprietary sortation system to remove glass and rock pieces from metals of a similar weight to result in a purity of 98 percent, says the company president. After a final polishing stage, the system produces a 0 to 3 mm copper and precious metals fraction and a 3 to 12 mm copper fraction of 95-percent purity, he says.

Stainless solutions

Stainless steel separators also are undergoing upgrades to collect hard-to-capture pieces. Certain alloys, such as 300-series stainless steel, are considered nonmagnetic, but the product manager of a Kansas company says the shredding process modifies the structure of the steel so it becomes weakly magnetic. The company’s newest sorter for stainless steel uses that weak magnetic property to its advantage by grabbing hold of stainless steel pieces 13 centimeters and smaller with very high-gauss magnetic pulleys, he says. The machine achieves better separation not only because of the high gauss, but because it has a proprietary, patented magnet circuit design that can pick up larger fractions better than similar machines, he says. Some customers have purchased the machine to get more stainless out of their Zurik fraction, while others have installed it behind their sensor separator to pull stainless out of their wire lines to protect chopper knives or to further purify the stainless steel metal fraction. Sensor separators “do a good job of pulling out stainless, but sometimes the purity isn’t there,” he says.

The Pennsylvania company recently introduced a stainless steel separator that also uses a magnet for work-hardened and 400-series stainless, but this model uses a permanent magnetic head pulley to pull out the metal, says a product manager for the company. This magnetic design, made specifically to capture pieces less than 5 centimeters, is a cost-saving alternative to using more expensive sensor sorters with compressed-air reject mechanisms, which can have “high capital expenses,” he says. One application is on a wire chopping line, “where the guys can protect the chopper blades by removing the stainless ahead of time,” he says, but the machine also can be used for recovering stainless steel from fine Zurik.

New stainless steel separators are also benefiting some customers that have stopped shipping their mixed metals abroad, the president of the Kentucky company says. “The biggest concern in the marketplace is [National Sword]. It’s easy to sell Zorba to China, but what if China shuts off?” he asks, referring to rumors that China might soon halt its imports of scrap. The solution for some processors is to buy equipment that will further separate their mixed metals so they can sell purified fractions directly to domestic smelters, the Kansas product manager says. Some customers are installing his company’s new stainless steel sorter as a way to achieve “a cleaner, high-purity stainless steel fraction, which they can sell to a domestic smelter versus shipping it to China, where you might get a lower price,” he says.

In the future, the Kentucky company president says, more equipment buyers will want sorters that can meet mill specs quickly and efficiently. His company is working to build more equipment that will meet those demands, he says. “You can sell brass or copper or zinc to the smelters. But where the tech is headed, it will get to the level where you can sort [5000 and 6000 series] out of an aluminum package,” he says. 

Advanced sorting with multiple sensors

Some manufacturers tout their new combination sorter models because customers can invest in one machine that does multiple tasks. “The nice thing about combination sorters is … as the markets change, you don’t have to go buy a new machine. You don’t have to use all the sensors all the time if you want to run a different material and get a different product,” says the president of the Kentucky company, which has a sensor sorter with five types of sensors: 3-D laser, brightness, color, inductive, and X-ray. The most recent model can be “infinitely programmed” for highly specific sorting tasks, he says. The company runs sample ASR through the sensor sorter and separates the material based on precise requests from customers. In one test, an operator programmed the sorter to pick out coins by telling the software to look not just for circular shapes, but to differentiate euros from U.S. coins, he says.

Another sensor-sorting company promises customers flexibility to sort a wide variety of metals with its new combination sorter that can handle “a multi-parameter material mix,” says a sales engineer for a New York distributor. The company claims its sorter offers the most sorting programs in the market, with a menu of options for sensor configurations that can sort metals by color or electromagnetic properties and polymers by color. It can recognize bare copper wire by shape and can pick out printed circuitboards, the company says.

The scrap market manager from Kentucky says his company’s near-infrared sorter uses hyperspectral imaging, which can be programmed to identify plastic bits as small as 4 mm in a metal stream. This can help spot circuitboard pieces in Zorba and other mixed metals. Ever since the Chinese government introduced initiatives such as National Sword and Green Fence to crack down on “foreign waste,” processors that ship metals to China are especially sensitive to the ways circuitboard contamination can negatively affect their shipments, he says.

Aluminum separation

Not all customers will need a do-it-all machine, but they might still want to refine Zorba into multiple fractions “to derive an extra value from the aluminum,” the New York company rep says. His company’s X-ray fluorescence sorter separates materials and pulls out aluminum from the heavier metals by determining the atomic density of each piece along the conveyor, he says. The aluminum fraction can go back through an eddy-current separator to get rid of the waste, leaving a pure Twitch fraction, he says.

Several other companies have advanced separators that target aluminum fractions, aiming to separate the various aluminum alloys. Once material moves through an XRF sorter, the New York sales engineer says, users can use the company’s laser-induced breakdown spectroscopy sorter, which identifies alloys using a plasma burst concentrated on the aluminum stream. “You can, for example, separate the 5000 from the 6000 alloys this way,” he says. This is a newer technology that is just now becoming available on the market, he says.

The Kentucky company also has introduced a new LIBS sorter for aluminum fractions. The ability to sort aluminum alloys in an economical way is relatively new, but necessary as automobile companies start using more and more aluminum in their vehicles and create more aluminum scrap, the company argues. Its LIBS machine can sort 5000 from 6000 alloys with a 99-percent purity rate if the pieces are between 20 and 60 mm wide and up to 150 mm long, the company says.

Calculating costs

Since recyclers buy advanced separators for myriad purposes and run a range of tonnages through these machines, costs will vary widely, manufacturers say. The Utah company co-founder says the cost of its new eddy-current separator is about $200,000 for a system that processes 150 kg an hour, which he says is on par with machines that do a similar job. Yet the up-front cost of the machine is just one factor in the overall costs, he adds. The company’s machine is designed to be installed behind sizing equipment, so recyclers would have to calculate the throughput and factor in the cost of that equipment, if they don’t have it currently, as well as maintenance costs for the interdependent systems.

Though the machines can be expensive to purchase and maintain, manufacturers argue the cost is worth it to capture fines that were once thought to be impractical or impossible to recover and sell. For example, the Florida separator manufacturer says its newest three-stage downstream system, which uses its eddy-current separator along with drying systems, an air gravity table, and other machines to reduce dirt and dust and produce high-purity fractions from fines, can yield about $70 to $74 of fine metals per ton of fines shredder residue (based on April 2017 commodity prices) because of the additional material it pulls from the stream. The president of the Kentucky sorter company says its new ECS can recover 5 to 10 percent more material than its previous models, and it is especially good at finding copper, which is fetching better prices than other metals in the stream. And the Pennsylvania separation company claims its newest ultra-high-frequency eddy-current separator can increase profits by up to $20,000 per month because it captures material older machines would have missed.

To get a feel for just how efficient and cost-effective a new separator will be, manufacturers recommend that recyclers send input material samples to multiple separator companies, which can shoot videos of the machines in action and calculate a return on investment based on tonnages and throughput. “It’s about getting every last little piece of metal out of the incoming stream. It’s about figuring out that extra profit,” the president of the Kentucky company says.

Downstream separation systems for recovering nonferrous metals and stainless steel—and removing contaminants—are getting sleek upgrades to capture and segregate material that was once thought to be out of reach.

  • 2017
  • Jul_Aug

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