June 27, 2003 By Justine Brown
Although most computer parts can be recycled and reused, cathode ray tubes (CRTs) are the exception. CRTs also are found in many televisions and contain an average of five to eight pounds of lead, a substance that is extremely difficult to dispose of. Lead can seep into groundwater under landfills or pollute the air if burned.
Silicon Valley Toxics Coalition recently released a report that predicts 500 million computers will become obsolete between 1997 and 2007, resulting in 1.58 billion pounds of lead. In response, many state and local governments passed legislation restricting the number of computers that can be placed in landfills. Those states are now faced with finding alternative ways to dispose of old technology.
Until now, the most common way to handle the CRT problem was to break down the glass to where the remaining material can be used as a flux in metal smelting refineries -- a process that pollutes the air. But researchers at the New Jersey Institute of Technology (NJIT) have a new solution. They recently developed an innovative method of dismantling CRTs that allows them to be recycled quickly and easily without creating additional pollution.
The new method allows CRTs to be sliced open using high-powered water jets, said Reggie Caudill, executive director of the Multi-Lifecycle Engineering Research Center Program at NJIT.
"To recycle a CRT, you need to be able to work the glass and get it clean by separating the lead components. The difficulty there has always been how to cut through the glass," Caudill said. "You need to separate the two different types of glass with reasonable levels of precision, so you don't mix them. We worked with our research group here to come up with an application using water jet technology to cut the CRTs."
Operating like soft saws, the water jets cut CRTs cleanly, separating the faceplates from the funnels using two dual-nozzle water jets. One nozzle is fixed to the side of a conveyor belt while the other is attached to a pivoting mechanical arm, which maintains alignment of the CRTs. As the CRTs move, opposing water jet nozzles cut through the faceplates. The monitors then move to the second cutting station, where opposing water jet nozzles cut the remaining two sides.
In addition to making the process easier, the NJIT method also automates it. Rather than manually feeding parts into a machine, NJIT uses a conveyer belt, making the process much more feasible for large-scale recycling. The CRTs begin on the belt as assembled units and emerge at the end completely separated.
The new process is also fast. Other methods -- like a traditional water saw or a hot wire technique (an electrical current is sent through a wire to make it hot, and a thermal shock separates the CRT) -- can take up to 5 minutes, Caudill said, but the water jet method takes only about 30 seconds.
The new method will allow recycling firms to disassemble electronic waste cleanly and effectively, Caudill said. They can then retrieve and resell the glass from the monitors.
"We've already had inquiries from recycling firms that want to purchase the technology," he said.
Ernest Geskin, professor of mechanical engineering at NJIT, heads the water jet project. "We are the only university in the country developing this technology," he said. "We think it will have a big impact on electronic recycling and protect the environment from toxic waste."
NJIT's water jet project was financed primarily by the New Jersey Commission on Science and Technology, which is dedicated to the transfer of technologies from the laboratory to the marketplace.
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