In the process of solving some of the challenges at Hycroft mine, President and CEO Randy Buffington says he believes they have something that will positively affect the future of gold mining.
The Hycroft mine has oxide ores and sulfide ores. The oxide ores can be successfully processed by the cyanide heap-leach method that is the backbone of much of Nevada's gold processing.
Hycroft has already improved the speed of processing the solution coming from the leach pads with their new Merrill-Crowe plant.
However, the leaching process doesn't work effectively with sulfide ores. Hycroft's mill expansion feasibility plan included leaching their oxide ores on site but selling the concentrate from the sulfide ores off-site for processing.
When Buffington was brought in to turn the operation around, one of the first things he identified was a need to find another effective, low-cost way to process sulfide ores to oxide ores for leaching so that Hycroft could process its own sulfide concentrate rather than sending it away for processing by autoclave or roasting.
Buffington brought in third-party metallurgical consultants to evaluate the possibilities. They evaluated the feasibility of oxidizing the ore using a simple, open-tank mixing process that would add air and oxygen to the concentrate along with a mineral called trono, which keeps the mixture at a pH that allows rapid oxidation in only 24-36 hours.
The now-oxidized ore can be leached in a tank at the mine; the pregnant leach solution is processed in the Merrill-Crowe plant to recover the gold and silver that can then be made into a doré bar, ready for sale.
That major breakthrough will allow Hycroft to complete all processes and create a doré bar on-site, compared with the previous plan to ship off concentrate to off-site autoclaves and smelters.
The process, "atmospheric alkaline oxidation," has been incorporated into their pre-feasibility study for the mill expansion, and Buffington believes it's a major breakthrough.
"It's a great project, and the technology that has been developed to bring this project into production will have a significant positive impact on Nevada," Buffington said. "The future of gold mining in Nevada has always relied on bringing forward a new process and making 'new ore.' Autoclaves, roasters, even heap leach have been part of this Nevada evolution in gold mining."
Buffington said he believes that what the team has accomplished at Hycroft will be the next step in this evolution.
"We will see many more mines become profitable because of the hard work this team has put into this project," he added.[[In-content Ad]]
