A green product 30 years in the making
Dr. John Whitney’s father was a farmer. But that wasn’t the life Whitney wanted for himself.
“I went into mining to get away from farming,” he explained.
Whitney earned his bachelor’s degree in geology, his master’s in mineralogy and a Ph.D. in mineral economics.
Forty years ago, Whitney was helping build the first silver heap leaching operation at a small mine in Nevada. At the same time, he and a few colleagues were working on a chemical process to separate silver from the cyanide solution used in heap leaching to collect gold from low grade ore. Little did Whitney know the project had put him on a path that led—in a roundabout way—back to farming.
Whitney continued experimenting with methods for recovering silver from mine materials well into the 1980s, when his work caught the attention of some civil servants with a problem.
“It was in the back half of 1986,” Whitney recalled. “A couple guys from Sparks and Reno called and asked if I’d be willing to meet with them—talk about a problem they had related to silver.”
It turned out that silver found in the spent chemical liquid used by one-hour photo shops, dentists, hospitals and x-ray facilities was making its way into the sewer system, and the sewage treatment plant was unable to remove it, so they ended up in the Truckee River.
Silver’s “toxic to fish when it’s in the water,” Whitney said. “And it’s really toxic to salmon and trout.”
According to Whitney, the U.S. Environmental Protection Agency threatened suit if the problem wasn’t fixed. Whitney agreed to test a sample of the photo chemicals and found that he was able to remove enough silver to satisfy EPA standards. When discharging photo-liquids to the sewer was banned in 1989, Whitney’s company—Itronics—was in a position to take over processing them.
But it turned out the problem was only half solved. When Whitney began receiving the liquids in bulk, he tested them further and discovered that they were also full of nitrogen and chrome-based cleaners used by photo processors. Taking the silver out wouldn’t make the liquids safe to go through the sewage treatment plant.
For a time, the county health department had Whitney remove the silver and then ship the liquids off to be mixed with water used for dust control on roads. It was a temporary fix that allowed Whitney time to hire a research librarian and start a worldwide patent survey to identify a commercial use for the leftover liquids.
“We took a year, and we found some patents that related to fertilizer-type materials that had similar chemistry,” Whitney recalled. “And I said, ’OK, so this might work. … nitrogen, iron, sulfur—all nutrients for plants.’”
With the help of his then-retired father, Whitney began testing the liquids in his own backyard to see if they could be made into a fertilizer. Eventually, he got it right. Today, Itronics recycles spent photographic liquids—turning them into silver bullion and a brand of specialty fertilizer called GOLD’n GRO, with a concentrated formula that poses a lower risk of groundwater contamination. Whitney and his company have won several green awards from local and international organizations.