Shredder Supplement -- Putting the Hammer to it

Bundles of number one heavy melt may still be the benchmark ferrous scrap grade, but there is no denying the growing presence of ferrous shred in the marketplace.

In the 1990s in particular, large-volume ferrous scrap processors seemed to acquire shredders almost as a sign that they were serious players in their regions.

The widespread growth of shredders in the 1980s and 1990s helped ferrous shred become a heavily traded grade.

THE SOUND AND THE FURY

The hammermill is a loud, violent, but most importantly, effective way to process scrap metal. The sound of dozens of metal-on-metal collisions occurring at once emanates from the machines, the largest of which can pulverize entire pick-up trucks and mini vans in a series of swift, high-impact actions.

Hammermills used by the recycling industry are available in a variety of sizes and horsepower strengths. While the earliest models used a 60-inch wide rotor as a standard size, manufacturers have introduced increasingly larger models, with sizes such as 80-inch, 98-inch and now 120-inch rotors available to high-volume scrap recyclers.

The super-sized shredders—those with 120-inch and 122-inch wide rotors—have gained the attention of the ferrous scrap industry this decade. When one of these machines enters a regional scrap market, it can have an immediate and significant impact as the owner or operator of the shredder begins to aggressively procure as much ferrous scrap as possible for feedstock.

While on the surface a super-sized shredder may only seem to offer a few extra inches of width on the infeed conveyor, its ability to process more tonnage than a smaller shredder is significant. A high-horsepower machine can also process materials not previously considered shredder feedstock.

“The super-sized shredder can process a range of materials historically reserved for owners of shears with 1,000 tons of capacity and lower,” says Terry Coker of Sunbelt Technologies Inc., Dallas. “It can consistently run bales and bundles and farm equipment, processing materials at rates of 200 to 350 tons per hour.”

High-volume processing rates like that are one reason why auto shredders—noise and all—have become a preferred processing machine for ferrous scrap processors.

MAKING THE GRADE

Those who shred ferrous scrap and design and sell shredding plants are strong advocates of the scrap grade produced by their machines.

They cite the density of the grade and the potential purity (when coupled with a good downstream system) as reasons ferrous shred is popular with foundries and mills.

“There is not a better way to process material to be mixed and processed in foundries and mills than shredding,” says Skip Anthony of the Svedala Recycling Division, Cedar Rapids, Iowa.

Consumers of ferrous shred have been favorable toward an increasingly dense version of the scrap grade. “There is definitely a trend toward denser scrap,” says Jim Schwartz of Texas Shredder Inc., San Antonio.

Among the advantages: a larger volume of the denser version of the grade can be transported in one gondola car. And perhaps more importantly, as the denser grade is produced, more copper can be separated from the ferrous product and shipped to mills.

“That’s always the case—the denser the product, the cleaner it becomes,” says Svedala’s Anthony. “We’ve seen a push for denser scrap from certain foundries and mills.” For processors, he notes, “it gives them the ability to get the maximum profit out of their product on both the ferrous and nonferrous sides.”

Schwartz says, “It is becoming rare now for processors to ship grades that are under 70 pounds per cubic foot. Some are making 80 and 90 pounds per cubic foot shred grades.” He adds that the move toward a denser product “is driven by the desire by mills to see less of the copper contaminant. The denser the material becomes, the more copper is probably out of it.”

When automobile engines, white goods or other obsolete copper-bearing items are shredded, “there is plenty of copper mixed into the initial shredded product, with much of it in the form of wires,” notes Schwartz. “The denser you shred the more the wire is chopped up into separate pieces and the better the chance the material will fall away because it is not intertwined with the ferrous scrap,” he adds.

As a bonus, Schwartz notes, other materials such as rubber, plastic or glass that may have found their way into the shredder also stand a better chance of being separated from the ferrous product.

Making a denser grade can involve a couple of different adjustments for shredder operators, with the most common one being the use of smaller grates. “The use of smaller grate openings is the main way to gain density, but you can also set it up to keep the shredder full. The material in the shredder mill seems to shred against itself,” says Schwartz.

Anthony notes that shredders can also be configured to “blind off certain sections of the shredder so the material is retained longer in the shredder. You could have just a top and bottom discharge with grates that are just a little smaller.”

He adds that while this may decrease throughput to some degree, most operators find it more worthwhile to produce the higher grade of shred that nets a premium from mills even if throughput is lessened.

DAMPENED, NOT SOAKED

Automobile shredders can attract attention, sometimes for the wrong reasons as far as nearby property owners are sometimes concerned.

The loud, energy-intensive process can produce bothersome dust if shredding is performed without the addition of water. While wet shredding can suppress the dust, it produces a considerable amount of dirty water that must be disposed of or purified on site.

In the past three years, a new process has emerged that has attracted the attention of some auto shredder operators. In the damp shredding process, water is added in regulated amounts so that enough is sprayed in to suppress dust, but only small enough amounts that will dissipate as steam as it performs its work.

Schwartz credits Trevor Masters of Mayer Parry Recycling Ltd., Erith, United Kingdom, with devising the damp shredding systems that first went into place at the company’ own shredder sites in the U.K.

“For years damp shredding had been talked about,” he remarks. “What made it work was the computer program and hardware setup configured by Masters and Mayer Parry.”

Schwartz notes that his company buys the technology from Mayer Parry to make it available to their customers in North America. “We’ve sold roughly 10 of these in the last year-and-a-half, some on new shredders, and we’ve also retrofitted old ones.” He says that all of the new plants sold in the past twelve months have the damp shredding system.

“Damp shredding is definitely the way most new shredders will be configured in the future,” he states. “You get to knock out the cyclones and fans and scrubbers—people get to save from $200,000 to $300,000 by not having to buy those things. And the foundation is simpler to build because you don’t have to worry about settling pits for water.”

“The trend is definitely away from wet or dry, with people implementing the systems that combine the best features of both,” says Anthony. “With damp shredding you get the dust suppression while being able to perform dry separation downstream.”

While it is not sold as such, Schwartz says the damp shredding configuration can also be recommended for safety reasons. “Damp shredding doesn’t eliminate explosions, but it turns medium-sized ones into small explosions and smaller ones into pops,” he remarks.

SHREDDER TRENDS

The replacement of wear parts presents a significant ongoing operating expense for auto shredding companies.

 The wearing down of hammers involved in constant metal-on-metal collisions is inevitable, but extra life that can be gained from hammers is appreciated. Makers of wear parts are indeed testing new alloys to deliver these longer-lasting hammers.

“There are some better alloy castings available on wear parts,” says Anthony, “so there has been increased wear life for some hammers, grates and liners.”

Scott Newell of Newell Industries Inc., San Antonio, says company personnel had observed  the first few bars of grates often wore out before the remaining grate bars. “We designed a set of grates so that the first few grate bars are cast with thicker webs than the remainder of the set.”

Although super-sized shredders have burst onto the scene, not every shredder order being placed is for one of the mammoth shredding plants.

At Texas Shredder, Schwartz says their 98/104 model has sold the best over the course of the past three years. The company’s most recent sale—to American Iron & Metal in Montreal, was of a 98/104 unit with a 5,000 horsepower engine and a damp shredding configuration.

Downstream systems that can provide the best possible sorting and separation of materials are still being reconfigured and tested by shredder operators and equipment manufacturers. “Downstreams have changed dramatically from the simple flow-through systems for just ferrous and nonferrous into extremely complicated and high-tech sorting systems—especially on the nonferrous side,” says Anthony.

In addition, Anthony says shredder operators are “looking for easier maintenance and longer wear life out of components.” He says customers in the shopping stage are “wanting more detailed information on things like operating cost per ton, electrical cost—things along that line. You have to be able to provide that kind of information to the customer, not just that the capacity is 150 tons per hour.”

Schwartz also cited ease of maintenance as a quality in demand from shredder customers. He says computer software designed specifically for scrap recyclers and even shredder operators is increasingly in demand.

Anthony notes that while auto shredding is far and away the leading use for hammermills in scrap metal applications, there are still a number of smaller and medium-sized shredders being used to process aluminum scrap. “Shredding is a good way to clean and prepare aluminum scrap for smelting,” he remarks.

STILL A GROWING TREND

While 1998 was a tough year for scrap recyclers and equipment makers, those involved in shredding say they are not concerned about any long-term effects resulting from the slump.

“The interest in and actual purchase of shredders has been there, even through the bad times,” says Anthony. “The American market is very resilient, there are indicators that we’re going to bounce back.”

“We have been very fortunate,” Schwartz says regarding Texas Shredder Inc. “In 1998 our parts sales were down because people just weren’t shredding, but our new shredder sales were very good,” he says. “The company’s fiscal year ran from July 1998 to June 1999 and we sold more shredders for new plants than I ever thought we would.” Schwartz indicates that of four recent shredders sold, three were at new locations while one was a replacement plant.

A survey conducted by Recycling Today in the summer of 1998 identified more than 200 auto shredders operating in the United States at that time, whie 21 auto shredders could be found in Canada.

Texas was the king of the auto shredding hill, with 19 shredders located in the Lone Star State. Ohio, Florida, Illinois, Michigan and New York were states hosting ten or more shredders at the time of the survey.

Globally, Japan was second to the U.S. in the number of auto shredders with a count o 187. Germany had 54 shredders, while France and the United Kingdom hosted 42 shredder plants each.

The ferrous scrap downturn of late 1998 has subsequently caused many of those shredders to fall silent, though it remains to be seen how many of them will be revved back up once  pricing and margins improve in the ferruos scrap market.

Much of the opportunity still remains in the North American market, especially when compared to the regulatory barriers being erected throughout much of Europe toward auto shredding. “There is already a big difference between shredding in Europe and the rest of the world, and that difference is going to grow,” says Schwartz.

“The end result is that cars are going to cost more over there,” says Schwartz. “They are probably going to dismantle cars, with shredders shredding what is left. It will be easy shredding, with fewer shredders operating and just bigger companies who will be certified to do the shredding,” Schwartz predicts.

Such changes do not seem imminent in North America, or in other markets such as Australia and South Africa that Schwartz says have been receptive to American auto shredding equipment. “I think that auto shredders have a big future every place but the continent of Europe,” he states.

“It’s the best way to process most forms of scrap,” says Anthony. “There’s nothing that can prepare material like shredding and proper downstream separation.” 

The author is editor of Recycling Today.