Wire Chopping Systems

May 26, 2017, 17:41 PM
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May-June 2017

The demand for cleaner metal chops has prompted wire and cable chopping line manufacturers to make incremental improvements to their systems to increase equipment efficiency and boost recovered metal percentages.

By Katie Pyzyk

CopperChopsSmallWire processors and equipment manufacturers alike say the past decade has brought a surge in attention to producing clean metal chops from scrap wire. Really clean. Sagging commodity prices and wire processors’ eagerness to separate every last bit of metal fines from plastic tailings have partially fueled the push. “In the past … customers didn’t care about having maybe 1 to 4 percent metal loss in the plastic fraction,” says the North American sales manager for a Denmark-based equipment manufacturer. But now “most customers look for a very, very clean end product” to maximize profits, he says.

Profits aren’t the only driver, though. “The specifications have gotten much more stringent” for recovered materials, both domestically and internationally, says Bernard Schilberg, CEO of Prime Materials Recovery (East Hartford, Conn.). “You have to have better [chopping and] separating equipment … to make a better finished product.”

Industry participants indicate the equipment has indeed improved in response to customer demand—in areas such as durability, efficiency, and separation techniques—and that’s creating renewed interest in cable and wire chopping.

Chop Logic

Chopping well outpaces stripping as processors’ preferred method for extracting metal from wires and cables. Stripping certainly has its place, particularly for smaller scrap operations or those just beginning to handle wire. But for many processors, the downsides of stripping outweigh the benefits.

Wire stripping equipment can only adequately handle a limited range of wire sizes, working best with cable or wire with a fairly large outside diameter, these processors say. The exact diameter is a matter of personal preference and experience, however. For Manitoba Corp. (Lancaster, N.Y.) President Brian Shine, the threshold is about 1 inch. “A lot of wire is smaller than 1 inch diameter, and you can’t strip it. It just doesn’t work,” he says. Universal Scrap Metals (Chicago) CEO Jason Zeid says his company will strip wire as small as 16 gauge, which has an approximate outside diameter of less than ¼ inch. “A lot of the wire that gets chopped is much finer than that, so it wouldn’t be conducive to stripping,” he says.

Another factor is the efficiency of chopping compared with stripping. “Chopping wire is a much faster process,” Zeid says. The CEO of an Oregon-based equipment manufacturer reinforces that point, offering the analogy that customers “don’t want the labor or the hassle of sucking spaghetti through a straw by feeding it one piece at a time,” as stripping requires. Many wire and cable processors thus prefer to invest in chopping equipment.

Maximum Metal Extraction

Wire chopping lines consist of several components customized to each purchaser’s needs. A basic line typically includes a preshredder, one or two granulators, and a materials separation system. An aspiration or dust-collection system also is common—and needed, the Denmark manufacturer’s rep says.

Preshredders have become the norm on the front end because they reduce wire masses to more manageable, relatively uniform lengths. “That’s the key. You can feed long, tangled wire through a [chopping] line, but it’s very inefficient,” Shine says. The Oregon-based manufacturer agrees. “With a prechopper, you’re going to run twice as much stuff with less labor.” Manufacturers have worked to improve preshredding efficiency and automation. “Our prechoppers now come with hydraulic ram assists, and they have a single rotating shaft with knives,” the manufacturer says.

A growing trend in copper recovery is installing a turbo mill after the initial granulator and before the separation table. This machine uses a different, more efficient technique to process materials, resulting in higher throughput and less maintenance, some manufacturers say.

A turbo mill vacuums size-reduced items into a drum where a series of more than 100 blunt paddles spin and hit the material. Unlike in a granulator, “the friction is not between two blades. The friction is between the paddles and material and the material and itself,” says the owner of a Connecticut-based equipment manufacturer. The motion creates tiny, dense metal balls because “the centrifugal force keeps the material toward the outside wall. ... It takes those little [copper] strands and rolls them in on themselves,” he says. “It does it so violently that the casing … just shatters right off of the copper.”

Some of these sources consider turbo mills a more economical and productive way to capture copper fines than using a second or third granulator. USM uses a turbo mill because “it [gives us] very low levels—almost nonexistent levels—of copper in our tailings,” Zeid says. The Connecticut-based manufacturer says the turbo mill “is at the top of the list for new innovations in this industry. … The granulator’s not obsolete quite yet, but we’re selling a lot less of them because of the turbo mill,” he says. For example, some customers who previously used two granulators in a chopping line recently sold their second granulator and instead installed a turbo mill.

This manufacturer says turbo mills require less adjustment and downtime than granulators do when switching between processing different types of raw materials. For instance, a processor who wants to granulate household wire one day and communication cable the next day would have to turn off the granulator, open it, and change screens. “With the turbo mill, it’s just a setting” the operator selects to run the mill at a different speed, allowing the material to stay in the machine for a longer or shorter period of time. He notes that material spends less time overall inside a turbo mill than in a granulator to achieve the same end product, and turbo mills offer greater output than granulators for the same horsepower. “If you had 100 hp, for example, and your throughput was 2,000 pounds per hour in your granulator, with the turbo mill your throughput roughly is closer to 3,500 pounds,” he says. And because it’s a screenless system, less material is lost.

Turbo mills produce a more uniform metal end product and simplify metal and plastic segregation when the materials move on to density separation equipment, the Connecticut-based manufacturer says. The metal “sinks to the bottom and climbs up the table a lot easier than it would if it were still in long strand form,” he says. 

Manufacturers have been improving separation systems as well. Wet separation systems aren’t always optimal because “water tables are very messy,” Zeid says. “A lot of people don’t use them because … it creates this copper sludge” when the copper and plastic particles mix with water. Another drawback of water separation, according to the Denmark manufacturer’s rep, is that “the metals are getting wet, and they can oxidize.” His company offers electrostatic separation equipment for customers who don’t like the wet separation. “That is actually quite new,” he says. “You get the last percentage—maybe 1 to 4 percent—of metal left in the plastic fraction” by using an electric charge to separate the conductive and nonconductive materials. Alternatively, “air separation is very effective, [so] we focus on that,” the Oregon manufacturer says.

The improved productivity and cost savings from the automation on new lines have revived interest in wire chopping, according to the Connecticut manufacturer. Vendors indicate an average of two people can operate most wire chopping lines, depending on the system’s size.

Right-Sizing the System

Purchasing a wire and cable chopping line requires a sizable capital investment. The expense varies significantly depending on each processor’s customizations, but vendors estimate a new line generally costs from about $40,000 to about $2 million on the high end.

Some manufacturers have introduced more compact and, for the most part, cheaper wire chopping systems. Last year a France-based manufacturer, for example, released a small, pre-wired chopping system housed in three cargo containers. A New York–based vendor of that product says it “allows a customer to have a full system that’s easy to integrate” into an existing processing operation because it requires less floor space and takes less time to install than traditional lines. The manufacturer’s modular version of its full chopping line can handle the same hard-to-process materials and is less expensive, at $1.5 million, he says.

Carefully consider your operation’s desired output when deciding between a traditional line and a newer, smaller one, caution some sources. “There’s been a lot of mini mills brought into the marketplace, but they’re for the smaller volumes, not for the larger volumes,” Schilberg says.

While some vendors find success promoting their compact systems, others promote the tried-and-true larger lines. “When the market is down, you’re making less margin, so you need to do more volume to make the same amount of money,” the Connecticut-based manufacturer says. Because of that, currently the large lines are “actually more popular than the smaller ones” at his company. Zeid has reached a similar conclusion through analyzing his chopping operation at USM. “I do think you need to go bigger … and have the right kind of volume to make these things work,” he says. Processors report outputs on large systems varying from 3,000 to 12,000 pounds an hour.

The Denmark-based manufacturer previously had sold only larger systems, but it recently acquired a company that specializes in smaller lines due to customer interest in those types of products. Thus far, though, the company’s North American sales manager says there have been “several inquiries for the smaller lines, but when we start talking with them we normally end up selling a bigger line than expected.”

Vendors highlight the hidden value of large wire chopping equipment by pointing out its versatility. The Connecticut manufacturer says its line can be upgraded to handle items like ballasts, radiators, and transformers. “There’s a whole array of materials that can be run through a wire chopping line, and only the ones who dare to try it find out,” he says.

Machinery Maintenance

Mentioning equipment maintenance produces a lot of groans among wire processors. “Realistically, the nature of a metal processing or chopping line is self-destructive,” Schilberg says, which makes maintenance “incredibly cumbersome.” That said, he points out the significant improvements to wire chopping equipment durability over the past 10 to 15 years. Increased blade quality, for example, means “you don’t have cracking of knives. … [And] the steel used on the inside of the granulator has become much better so [its components] don’t wear as quickly,” he says.

Hardier equipment allows manufacturers to tout “applications that historically couldn’t be handled by traditional wire-chopping systems,” such as thick communication cables or wire from automobile shredder residue, due to ferrous and other content that would wear the granulator very quickly, the New York–based vendor says. “It’s giving the customer the opportunity to take advantage of low-quality materials and produce high-purity copper and aluminum fractions.”

The most maintenance-intensive areas of a wire chopping system tend to be the preshredder and granulator blades as well as the screens. The blades need consistent sharpening or replacement, which “can be very expensive,” Zeid says. He emphasizes the importance of daily maintenance, however, such as monitoring and adjusting cutting gaps, greasing bearings, and cleaning the line. “If one part of the system starts struggling, you’re not getting the throughput you want, and it’s going to affect the other parts rapidly,” he says.

For chopping lines using turbo mills, maintenance proves less intensive because they contain fewer wear parts. “There are no screens, there are no bed knives, there are only the rotor blades,” the Connecticut-based manufacturer says.

Frequent maintenance and cleaning improve overall equipment longevity, manufacturers say. Although the New York–based vendor tells customers the chopping lines have at least a 10- to 15-year life expectancy, he showcases some processors who diligently perform maintenance on their machinery and still run it after almost 25 years. “We’ve got systems … installed in 1993 here in North America, and they’re still going,” he says. “They’re super robust.”

Many manufacturers and vendors offer ongoing service contracts to equipment purchasers. “We have service available nearly 24/7. … That’s very important for the customer so they don’t have downtime,” says the Denmark manufacturer’s rep. His company recognizes the machinery’s complexity and prioritizes providing rapid customer service and thorough equipment training. “It is important to know the customer is comfortable with what they get from us,” he says.

New technologies also make it easier for users and manufacturers to detect and diagnose problems. “We have smart controls now … so all the pieces are ‘talking,’” the Oregon manufacturer says. On some modern lines, the components not only “talk” to each other, but also directly to the vendor or manufacturer, who can remotely take over the system to work through problems. “We can access them right here from our plant and get into their controls,” he says. “It saves everyone a ton of time and trouble, … [and] we don’t have to put somebody on a plane” to the customer site.

Increased automation reduces maintenance and replacement-part expenses as well as lowering labor costs. “Automation is making the machines last a lot longer” and run more smoothly, the Connecticut manufacturer says.

Tricky Tailings

Tailings are a nuisance both for chopping line manufacturers and for scrap processors. On the manufacturing end, companies rigorously search for and test the most effective methods to thoroughly separate the cable coatings from the metal. For processors, the trouble lies in what to do with the separated insulation.

The low quality and sheer number of different polymers used to coat the wires makes the material difficult to market. In fact, plastic isn’t the only jacketing and insulation material; the wire also can be wrapped with materials such as rubber or paper, further contributing to the difficulty.

Most processors end up sending the vast majority—if not all—of their tailings to the landfill. “Unfortunately, at this point it’s not a valued item. Nobody is paying for it,” Shine says. A small portion of tailings can be sold for repurposing, but processors report such markets are narrow and often don’t pay off. “We do have some periodic markets that we can sell to, where they’re making different types of plastic bricks and park benches and such,” Zeid says. “But the market is pretty limited.”

Some processors even have learned that customers who purchased tailings weren’t recycling them, as had been expected. Instead, they send the plastic remnants through their own separation systems to harvest any remaining copper fines. In those cases, the tailings typically still end up in a landfill.

Manufacturers of wire chopping lines report that they hear these customer concerns and are working toward better tailings solutions by “developing new processes to recover the plastics in the tailings … to create a product that they could sell,” the New York–based vendor says.

That’s welcome news for processors. “I think we need more downstream capabilities to further separate the polymers and be able to upgrade them and extrude them into a pellet,” Schilberg says. Prime Materials Recovery has created proprietary processes for separating and recycling most of the polymers it encounters in its tailings, he says, “but there’s not a good market. Realistically, you do it for landfill avoidance.” 

Creating more value from the tailings would be a boon to a scrap processing segment that has faced some challenging times. Manufacturers and vendors say that although they’ve recently endured lagging equipment sales due to the commodity price slump, the past year has offered a modest turnaround. Wire and cable processors also cite market improvements, which is notable because of this sector’s influence on the supply chain, Shine says.

“Not everybody can consume or handle insulated copper wire. By liberating the copper from the insulation, we’ve created a product that is very easy to market and recycle,” Shine says. “It’s a challenging model at times, but it’s a very important part [of the recycling industry], too.”

Katie Pyzyk is a contributing writer for Scrap.

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