A pioneer of the state’s cyanide heap-leach technology is now testing a cleaner, zero-waste approach to mineral extraction that could revolutionize the industry.
The process has potential to unlock unrealized resources in previously mined material, and some proponents hope in its ability to extract precious metals from virgin ore.
Testing of an extracting liquid began on previously leached material from Comstock Mining Inc.’s nonactive Lucerne Mine in August 2017. Results a year later show that the technology can reduce cyanide while extracting valuable minerals, including silver and gold.
Corrado De Gasperis, Comstock executive chairman, president and CEO, called the science a “breakthrough from a metallurgical and cost perspective.”
Through chemistry, the system also could leave soil clean and nutrient rich, possibly reducing permitting and bonding requirements by eliminating toxins and fertilizing the ground.
“That’s one of the biggest barriers we have,” said Dr. John Whitney, president of Reno-based Itronics Inc., an award-winning green technology specialty fertilizer and silver refining company. “It sounds too good to be true.”
Whitney moved to Nevada in 1975 to develop a small silver mine east of Fallon. There, he met a resident who made a living by extracting high-grade ore with an old-timey cyanide leaching circuit on 6 yards of material at a time in his backyard.
“I said, ‘Man, this is interesting,’” Whitney said. “So I said, ‘OK, this is how we start.’”
Inspired, he and a team developed a small, 400-ton-per-day silver leaching operation that, with some backing from the then-U.S. Bureau of Mines, introduced the state’s first heap-leach pad using cyanide for silver extraction. He recalled installing drip irrigation-like infrastructure to distribute the cyanide solution.
“Nobody had done it before, so it was really the beginning,” Whitney said. “There was a lot of stuff we had to figure out.”
Despite the metallurgical successes, the Fallon mine failed operationally when old equipment reached the limit of its lifespan and was too expensive to fix.
“So I ended up with the technology, and that’s where I learned how to extract with cyanide,” Whitney said.
Meanwhile, the scientist finished his doctorate in mineral economics. Through Whitney & Whitney Inc. consulting business, he provided services to the U.S. Department of Interior and to mining companies around the world. In 10 years, he said his firm helped develop about 10 mines with about $1 billion in investments resulting from his work. Projects included the Northumberland gold-silver mine in Nye County and the Red Dog zinc mine in Alaska. He also assisted with geologic exploration for U.S. Steel in Lyon County and for Jerritt Canyon in the Independence Mountains northwest of Elko.
“I did [mining] because I wanted to know how it works,” Whitney said.
In the mid-1980s, the cities of Reno and Sparks approached Whitney for a solution to a chemistry problem that imperiled cutthroat trout living in the Truckee River. Silver-bearing photo liquid being released into the sewer was killing the fish because the water treatment plant could not remove the silver. The authorities asked if he could remove the silver.
“At that time, I didn’t have a clue,” Whitney said, but his first test to remove the silver worked. “And they said, ‘Boy, you solved our problem.’”
Because the state needed a solution to its potential environmental tragedy, authorities dubbed one of Whitney’s operations — an Itronics pilot plant dedicated to extracting silver from silver-bearing sludge from used photographic liquids — as a “silver recycler,” he said. A permit under reclamation laws allowed him to proceed with a program to clean the river water and ultimately, save the trout.
“Bottom line is, I like to solve problems,” Whitney said, “and it’s fun to work on complicated problems.”
Next, Whitney had to solve the challenge of what to do with the leftover liquid, which was not harmful but considered orphaned because it didn’t have a use.
“It was stranded in space and time,” Whitney said. “The chemical is special.”
He had ideas for using the remaining liquid — thiosulfate-based chemistry — in the mining and agricultural industries. Solutions generated at Itronics contain a proprietary blend of components including sulfur and iron through a proprietary process. Itronics owns and operates a facility in Stead that extracts metals from photographic and electronic waste, such as computer circuit boards.
Because of his early work with extraction technology in mining, Whitney knew that sodium thiosulfate has been used in the United States as part of an antidote for cyanide poisoning. He reasoned that his stranded liquid solution could neutralize cyanide.
Tests of previously leached minerals from a large Nevada gold mine in the 1990s not only verified his theory, but also showed that the process had the ability to extract a high percentage of residual gold and silver in waste rock.
“I said, ‘Geez, this is interesting,’” Whitney said.
A change in management at the mine led to the elimination of its engineering and exploration departments, and the operation lost interest in Whitney’s experiments. Still wanting to use the stranded liquids from his plant, he turned to agriculture.
Research indicated that the liquid could be used for nutrition, he said, and the company spent about 15 years refining a product that is now sold as fertilizer in Nevada and California. There are 11 fertilizers sold under the GOLD’n GRO trademark. Through wholesale distributors, the fertilizer is shipped to large-scale farms and is available for sale in small quantities on Amazon.com.
Today, Itronics is recognized as a zero-waste operation because it converts spent hazardous silver-bearing liquids into fertilizer, silver bullion, and silver-bearing glass.
“Eventually, we will become a producer of pure metals,” Whitney said. “That’s our goal.”
The company also controls, through a partially owned subsidiary, Auric Gold & Minerals Inc., an oxide copper gold mineral property in Yerington.
Years later, Whitney has found increased potential in recycling e-waste, one of the world’s fastest growing waste streams, according to the 2017 Global E-waste Monitor. Itronic’s uptick in recycling using e-waste means an increase in stranded liquid and a renewed ability to apply it in industries other than agriculture, including his original interest: mining.
“Now we are at a point that we can take on a bigger project,” Whitney said.
Comstock’s Lucerne Mine has 3 million tons of previously leached material that contains residual cyanide. The site has a $7 million reclamation bond, De Gasperis said in his second-quarter financial results conference in August.
With Itronics’ fertilizers, rebranded as KAM-Thio for use in the mining industry, Whitney proposed a solution for Comstock.
“So why don’t we do some tests and see if we can clean it up for you?” he recalled asking.
After about a year of Itronics-funded testing verified by independent laboratories, De Gasperis explained to investors that the liquid reduces the cyanide to better-than drinking standard requirements and cleans the remaining rock. The field-tested, registered fertilizer also extracted most of the leftover base-metal oxides, including gold and silver, Whitney said.
“KAM-Thio leaching test results … are demonstrating that the residual silver, gold, base metals, and cyanide can still be removed from the previously leached material, creating a potentially efficient and environmentally attractive process,” according to a May 2018 Itronics press release.
Whitney advocates that leaching with KAM-Thio also allows the separation of other sellable minerals including silica, aggregates and other minerals. Additionally, any remaining KAM-Thio — a low-grade nutrient solution that is clean — could act as a fertilizer.
Using a field-tested, registered fertilizer for extraction and remediation could reduce bonding requirements for mines, Whitney said.
“Now you might turn a $7 million liability into a $20 million to $25 million asset that’s producing cash on a daily basis,” De Gasperis said.
Excited about the advancements, De Gasperis wondered how the cyanide alternative would work on virgin ore. He plans to test untreated material from Comstock’s Dayton project.
“I know what Corrado wants, but our focus is … whether a reclamation project could be established in the short term,” Whitney said, explaining that the sale of industrial mineral byproducts could provide a safety cushion against fluctuating precious metal prices.
Comstock is conducting screening-level economics on the KAM-Thio process.
“At Comstock, I think it could work under current economics,” Whitney said. “Maybe it’s hopeful but I think it actually will work — and work means economically not just chemically.”
The system might become economical for more widespread use if metal prices increase, or the technology could be useful to a larger mine, Whitney said.
Through Whitney’s preferred business model still under development, mines would purchase the KAM-Thio liquid from Itronics through a joint venture or a partnership. Extraction and recovery would be completed at the mine site using Itronics technology under a license agreement. The company would retain ownership of the technology and formulas.
“In the future,” Whitney said, “it could be very, very valuable.”
For the present, Whitney is back where he started 40 years ago, building on a system he helped pioneer.
Whitney’s early experience using cyanide for mineral extraction — combined with knowledge gained from removing silver from water — was a precursor to the potentially groundbreaking technology he explores today.
“Who would think that beginning would lead to this?” Whitney asked.