In a scarred Utah canyon, spread over the world's largest open-pit mine, lies a nasty secret: tons and tons of dissolved steel and tin from the recycling bins of homes in San Jose.

The empty food cans that environmentally conscious people thought they were recycling at the curb are actually turned into a toxic, molten brew and sprayed atop mounds of dirt at Kennecott Copper's Bingham Canyon mine.To produce a few pounds of copper, hundreds of tons of cans collected throughout the Bay area are consumed in a sulfuric-acid solution. The throw-away cans stay out of local dumps but sit forever as hazardous waste in a 10-square-mile gash in the Utah earth.

Environmentalists and advocates of recycling programs said they were shocked to learn what had become of the cans.

"It's tragic. Using these cans to mine copper is not recycling," said Sandra Jerabek, executive director of Californians Against Waste. "It's ironic that material people think is helping the environment is used in such a destructive manner."

Although the copper mine has been a final resting place for most of northern California's "recycled" food cans for years, San Jose and state waste management officials said they had no idea how the cans were used.

Exasperated city officials said the only buyer for their curbside-recycled tin cans is a San Joaquin Valley metals broker, who in turn profits by shipping the shredded metal to Kennecott."I can't tell you we knew about it because we didn't," said Michelle Yesney, San Jose's director of environmental management. "I don't think it ever occurred to us that something like this would happen."

Factories that recycle used food cans exist in the Northwest, but there are none in northern California. And steel recyclers say they don't make enough money to pay the cost of shipping the cans elsewhere.

"For the time being, I'm not sure we can do much about it," Yesney said. "We will investigate alternatives, but it's important to us that we keep the cans out of our landfill."

California law requires cities to reduce the amount of trash they send to the dump by half by the year 2000. Recycling has been encouraged as the ultimate solution to overflowing landfills. But cities don't have to follow up on where their recycled material goes, once it's been sold.

At Proler International's plant in Lathrop, Calif., which collects "recycled" metal from all over northern California, "we are only set up to serve the copper mine," plant manager Don New said. "We just shred it and send it over there."

The shredded cans, along with all kinds of other discarded metal, go by train to Copperton, Utah.

"More earth and material is moved here than anywhere," said Greg Boyce, government affairs director for Kennecott Copper Corp. "We use the steel from San Jose's cans as a consumable product within our precipitation plant to produce copper. It helps us to produce the copper used in electrical wiring for buildings and cars."

According to Boyce, Kennecott melts the steel and dissolves it in a sulfuric acid solution, which is then sprayed onto "leach dumps" - huge piles of mined rock - to leach out minute copper particles.

Kennecott says it has just spent $400 million on lined ponds and other improvements to comply with federal laws and prevent groundwater contamination. But according to the Environmental Protection Agency, the leaching process at Bingham Canyon still creates hazardous waste.

The steel that isn't dissolved by the sulfuric acid ultimately forms an iron crust on top of the mounds of mined rock. Once the copper is mined, the crusted piles are abandoned and new piles are created. The steel can never be reclaimed.

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(Additional information)

Is it recycling?

If you put your empty cans into recycling bins instead of out with the regular trash, you probably assume that the steel and tin are being recycled into another generation of food cans. But some northern Californians' cans are "recycled" into a sulfuric-acid solution as part of Kennecott's copper-mine operation.