November/December 1997
With its high-temperature metal recovery process, Inmetco has become a leader in the Ni-Cd battery recycling niche. Here’s a look at the company and how it recycles these rechargeable power sources.
By Kristina Rundquist
Kristina Rundquist is an associate editor of Scrap.
If you own a laptop computer, cellular phone, cordless tool, video camcorder, or virtually any other cordless, electric-powered product, you’re likely to be the proud owner of one or more nickel-cadmium batteries. Ni-Cds, as they’re nicknamed, are the rechargeable energy source that enables products to be portable.
In addition to your scaled-down consumer Ni-Cds, there are industrial versions that do everything from keeping the signal lights at railroad crossings working to providing the juice to keep an airplane’s emergency lights and electrical systems running.
While these powerhouse batteries are rechargeable many times over, they don’t last forever. Which is unfortunate news for you, but a boon to International Metals Reclamation Co. Inc. (Inmetco), which operates the only commercial high-temperature cadmium recovery operation in North America. Last year, the company—based near Pittsburgh in Ellwood City, Pa.—recycled more than 3,000 tons of Ni-Cd batteries culled from both industrial and consumer outlets. And with Ni-Cd collection efforts gaining a broader foothold, its tonnage seems likely to increase in the future.
So, how exactly do you recycle a Ni-Cd battery? Read on to find out.
Getting Into the Act
But first, let’s review some Ni-Cd recycling history.
In the past, these rechargeable wonders were discarded after outliving their usefulness. More recently, laws were passed to govern their disposal, primarily because of their cadmium content. (Spent Ni-Cd batteries were classified as a hazardous waste.) Though these laws were well-intentioned, they varied from state to state, with each requiring different means of transportation and treatment. Thus, battery manufacturers and consumer outlets were often at a loss as to how to properly dispose of Ni-Cds—a problem only exacerbated with the growing popularity of portable products.
To ease this burden, President Clinton signed into law the Mercury Containing and Rechargeable Battery Management Act in May 1996, which created a federal system to govern, among other things, Ni-Cd battery recycling.
Part of this legislation redefined Ni-Cd batteries from a hazardous waste to a “universal waste,” which changed the way in which cadmium and cadmium-containing products could be shipped. Before this act, shippers were required to complete a hazardous waste manifest and were also required to find properly licensed transportation companies for each state through which the batteries would pass. “If you had to ship from California to Pennsylvania, the carrier had to be a licensed Pennsylvania hazardous-waste transporter,” explains David McComas, Inmetco’s vice president. “Even if you were able to find someone licensed, it was still very expensive because each state had its own transportation regulations. So if you had to cross six states, you simply didn’t recycle Ni-Cd batteries. The desire was there but it just wasn’t practical.”
The act not only freed shippers from having to fill out a hazardous waste manifest, but it also enabled them to ship Ni-Cds via common carriers, which meant less expensive transportation costs and less hassle. “Once shippers could use common carriers, transportation became cheaper and as the reasoning goes, people are more likely to recycle,” McComas says.
In short, the act offered welcome relief to battery manufacturers and collection sites—and gave Inmetco an easier, clearer path toward its goal of recycling Ni-Cd batteries.
Plugging Into Ni-Cds
Interestingly, Inmetco wasn’t founded to recycle Ni-Cds. Its initial focus was processing stainless steel wastes to recover nickel, chromium, and iron for reuse in stainless steel production.
Soon after Inmetco opened its doors in 1978, however, the stainless steel business suffered hard times, leaving the firm with idle capacity. In response, its executives decided to explore alternative markets, which made sense given that the operation was equipped to recycle just about anything that contained nickel, chromium, and iron. “We looked for materials that included these metals to see what might fit our purpose, and one thing that fit the bill was Ni-Cd batteries,” says McComas.
Inmetco has, in fact, been recycling industrial Ni-Cds since the early 1990s using its proprietary high-temperature metal recovery process, a method that has been recognized by the U.S. EPA as the best demonstrated available technology for recycling Ni-Cd batteries.
When Inmetco first tried its hand at Ni-Cd recycling, it recovered the nickel from spent batteries and sent the cadmium to another battery company for processing. “But to better serve our customers, we became committed to installing a cadmium-recovery facility on-site,” says Richard Hanewald, president.
Sure enough, in December 1995, Inmetco officially began its commercial cadmium recovery operation, which works in conjunction with its stainless steel waste recycling unit. Today, the company receives spent Ni-Cd batteries from not only the States, but elsewhere in the world including Canada, which has recently started its own voluntary Ni-Cd battery recycling program modeled after the U.S. program managed by the nonprofit Rechargeable Battery Recycling Corp. (RBRC) (Atlanta).
In the U.S. program, Ni-Cd battery manufacturers sign an agreement with the RBRC and pay a fee to gain the right to place the recycling seal on their batteries’ packaging. The RBRC then uses these funds to pay the processing and transportation fees of these batteries when they are turned in for recycling, eventually making their way to Inmetco’s 100-acre facility. The RBRC runs other programs in partnership with Inmetco that provide for a variety of collection methods.
Moreover, small businesses, battery manufacturers, and local municipal collection facilities can contract to recycle their batteries with Inmetco in a variety of ways. These include but are not limited to prepaid container and mail-in programs whereby consumers send their used batteries either back to the manufacturer or directly to Inmetco, as well as milk-runs where Inmetco organizes a pickup route.
In whatever way the spent batteries reach Inmetco’s door, they all meet the same recycling fate, as described below.
A Shot of Cadmium
Ni-Cd batteries are recycled at Inmetco in a two-stage process.
The first stage recovers cadmium for reuse by battery manufacturers. The second stage focuses on the batteries’ nickel and iron content, which is smelted and cast into pig iron for reuse by stainless steel mills.
Inmetco recycles both industrial and consumer batteries, which come in a variety of configurations—some resembling videotapes and even car batteries. Industrial Ni-Cds consist of layered nickel and cadmium plates bathed in a potassium hydroxide solution. During processing, a battery’s top is cut off with a band saw and the electrolyte is drained and used as a pH control reagent in Inmetco’s wastewater treatment system. Next, the plates are hand-separated, then mechanically washed and dried.
The cadmium plates are transported on a conveyor belt, with carbon being added en route as a reductant. As the plates reach the end of the conveyor, they tumble into one of eight cadmium recovery crucibles. When full, each crucible is transferred by overhead crane to the retort furnace, which can hold four crucibles. After being covered with a lid, each crucible is heated to 1,500oF—hot enough to vaporize the cadmium on the plates. This heating process takes about 18 hours, including two hours to allow the crucibles to cool so no fumes escape when their lids are removed.
Once vaporization has occurred, the cadmium fume is condensed in one of the firm’s four electric cadmium distillation furnaces, which are computer-operated and feature computer monitoring stations in the control room as well as on the plant floor. They enable employees to check the monitors directly if a problem develops rather than having to go to the control room. “It’s just another way for us to run efficiently,” says McComas.
Once in the distillation furnaces, as the cadmium vapor cools and turns into liquid, it flows down along a drain pipe into a water tank which, when it hits the water, is turned into roughly 1/4-inch shots of 99.99-percent-pure cadmium. The shots, similar in appearance to tiny clam shells, are then packaged in drums, weighed, assayed, and shipped to Ni-Cd battery manufacturers. In the end, about 250 pounds of cadmium shot are produced from each crucible’s initial 1,400 pounds of cadmium-bearing battery plates.
Consumer batteries, meanwhile, begin their recycling journey in Inmetco’s main facility, an expansive 35-acre covered building. Here, they are placed in a natural gas-fired thermal-oxidizer furnace, which burns off the batteries’ plastic casings and paper wrappings. The fumes from this process are channeled into the company’s rotary-hearth furnace and used as a fuel source, while the batteries are transported in bins to the cadmium recovery building where they are placed on the conveyor destined for the crucibles and retort furnace.
And so ends cadmium’s ride through Inmetco’s recycling process.
Turning a Sow’s Ear Into Pigs
Nickel, on the other hand, has a longer road to travel.
After being separated from the cadmium plates, washed, and dried, the positively charged nickel and iron plates are shredded, then mixed with a variety of waste feeds that Inmetco processes for stainless steel producers, including flue dust, mill scale, and swarf, an oily substance that springs from the belt grindings of stainless steel.
Whether it arrives by pneumatic truck—as flue dust does—or conventional dump truck, these materials are stored in large silos and bins while they await processing. Materials such as swarf and mill scale—a flaky substance formed on the surface of stainless steel as it oxidizes during flat rolling and forging—must undergo processing before entering the high-temperature metal recovery process. Mill scale, for instance, is passed through a series of screens and a rod mill before it’s deemed ready, while swarf is tumbled through a rotary-drum swarf-breaker.
When ready, these materials—along with nickel cake, carbon, and certain metal-bearing liquids—are blended in precise amounts by mass-flow bins that are regulated by electronic speed controls. The mix is conveyed into a screw conveyor where it’s mixed with water and carbon or coke. Passing through a disc pelletizer, the mixture is transformed into green pellets approximately 1/4-inch in diameter and strong enough to survive the next stage—the rotary-hearth furnace.
As the pellets pass into the 55-foot-wide furnace, they are blended with more coke and special additives. The pellets take a 20-minute trip around the rotating floor of this doughnut-shaped furnace, where they’re heated to approximately 2,300oF.
During this stage, the oxidized pellets are partially reduced to their metallic states as the carbon reacts with the oxygen. Contaminants such as zinc and lead are vented into Inmetco’s air scrubbing system and are eventually sold to another Pennsylvania recycler for further treatment and processing.
After having passed through the rotary hearth, the metallic pellets are transferred in sealed containers via overhead crane to the submerged electric-arc furnace. Once in the furnace, various fluxes are added to the molten mixture to help with slag chemistry and the contents are heated to 2,750oF. The heat brings about two changes: First, the chromium oxides react with residual carbon, reducing the mixture even further. And second, lime, silica, magnesia, and alumina separate, forming a liquid slag and leaving behind a bath of nickel, chromium, and iron.
Periodically, the slag and metal baths are tapped from the furnace into ladles. The slag is then poured into thin sheets, cooled, and subsequently crushed, sized, and sold for use in construction and as road aggregate. The metal bath, meanwhile, is carried by overhead crane to a twin-strand pig caster, which can cast 15 tons an hour, according to Mark Schweers, senior adviser for marketing and research. When cooled, the pigs are shipped to stainless steel manufacturers to be turned into anything, including the kitchen sink.
Environmental Expertise
Inmetco does so much recycling of stainless steel, Schweers maintains, that “if you have anything in your house that was produced from domestic stainless steel, odds are that it contains Inmetco remelt alloy.”
In addition to offering stainless steel waste recycling services and recycling Ni-Cds, Inmetco functions as an environmental services company, catering to generators of metallic wastes from other industries that it can process and sell to the stainless steel industry.
The key to being successful in both its stainless steel waste-processing and environmental service roles extends far beyond offering prompt service and good prices, say Inmetco’s principals. The key is based on the firm’s long history of environmental health and safety combined with its rigorous quality control system. As Hanewald explains, “We’ve been entrusted by our customers to manage their waste in an environmentally safe manner. They don’t want future liability—a good number of our long-time customers have already been named once as a PRP in a hazardous material site cleanup and they don’t want to go through that again. Recycling makes sense for them, and our job is to make sure it’s done properly.”
How does Inmetco do it properly? For one, the company has an on-site lab that operates around the clock, 365 days a year. To keep quality problems at a minimum, potential customers must send in a representative sample of the material they want processed before Inmetco will agree to accept it, says Schweers. And after a load arrives, another sample is taken for analysis.
Then, at every stage of Inmetco’s process, samples are taken and analyzed to determine their metal content, not just for the much-wanted substances like nickel, chrome, and iron, but also for contaminants. Some of the biggest threats to stainless steel producers are cobalt, tin, copper, and phosphorous. And after processing, even the slag is analyzed.
All of these samples are analyzed in Inmetco’s in-house lab, which contains a slew of high-tech equipment. A new state-of-the-art X-ray spectrometer, for example, provides a computer printout on each element analyzed, which is then electronically transmitted to the electric-arc furnace control room, enabling the operators to make the appropriate feed and slag adjustments. Plant chemist Russ Bleakney and his four-person staff grind each sample before pressing it into a disc. Depending on its type, the sample is then subjected to one or more tests. For example, cadmium must be tested using an atomic absorption spectrophotometer unit that can take more than 30 minutes per sample to analyze. Samples are held for several months so the lab can perform additional testing of composites if required. When the lab is finished with the samples, they’re returned to the recycling operation for remelting, notes Bleakney.
As far as pollution and environmental health and safety goes, Inmetco has a sparkling record, its principals say. The company recently spent more than $5 million to upgrade its electric-arc furnace baghouse and the in-plant dust collection systems “to do a better job in evacuating fugitive emissions generated in the plant,” McComas says. It also has a wet scrubber on-site to collect and process fumes from the rotary-hearth furnace. The wet scrubber, in fact, is part of the firm’s permitting requirements with the state of Pennsylvania, says Hanewald, noting, “We must meet their schedule and the requirements of the Clean Air Act.”
Despite the challenge of processing potentially hazardous materials such as cadmium, Inmetco has managed to surpass the environmental regulations on more than one occasion. “Perhaps where we’ve excelled beyond state or local ordinances is with our water discharge,” Hanewald boasts, pointing out that the firm has installed a device that can remove heavy metals to 0.5 parts per million. “That’s literally 50 percent less than what’s required.”
And years ago, the company implemented a system to reduce the quantity of its discharge water. “When I started here in 1979, we discharged about 280,000 gallons a day,” Hanewald recounts. “Initially, we cut that figure in half. Then, with a later treatment operation, we began recycling even more so that now it’s only about 10,000 gallons a day.”
In Hanewald’s view, a large portion of Inmetco’s success is due to its environmental practices, a commitment that has not gone unnoticed. In 1995, for instance, the company received four awards from various Pennsylvania state environmental groups—for excellence in the development of a Ni-Cd battery recycling and collection program (PRC Recognition Award), for demonstrating a commitment to environmental excellence, leadership, and accomplishment (Three Rivers Environmental Award), for establishing a superior multimedia waste minimization program and its marketing campaign (Governor’s Waste Minimization Award), and for its work with government facilities in promoting community recycling (Act 198 Grant), for which it received a $100,000 state grant.
Inmetco’s environmental efforts are all in keeping with the pledge on its business cards: “To promote sustainable development, balancing economic growth with good stewardship in the protection of human health and the natural environment.”
“That simple statement took a long time to develop,” notes Hanewald, “but it’s a philosophy that Inmetco follows.”
And it’s that philosophy that has given the Ni-Cd from your cordless drill a recycling home. •
With its high-temperature metal recovery process, Inmetco has become a leader in the Ni-Cd battery recycling niche. Here's a look at the company and how it recycles these rechargeable power sources.