Agreement To Evaluate Use Of Nuton Copper Heap Leaching Technologies

PHOENIX, AZ - Excelsior Mining Corp. has entered into a Collaboration Agreement with Nuton LLC, a Rio Tinto venture, to evaluate the use of its Nuton™ copper heap leaching technologies at Excelsior's Johnson Camp mine in Cochise County, Arizona.

Rio Tinto has developed the Nuton technologies, an extensive portfolio of advanced copper heap leaching technologies targeted at primary sulfide minerals (including lower grade minerals), which could not otherwise be processed using traditional leaching or sulfide processing technologies. These technologies offer the potential to produce additional copper in a cost-effective manner that has significant environmental benefits and reduces waste from new and ongoing operations.

The first stage of the collaboration involves Nuton completing certain test work on materials collected from the Company's Johnson Camp mine project to confirm that suitable conditions exist to deploy the Nuton technologies. Assuming this test work is successful, the parties would then work toward negotiating commercial terms for a full-scale deployment of the Nuton technologies at the Johnson Camp mine. Test work is expected to commence during the first quarter of 2023 with a view toward potentially negotiating commercial terms dependent on the test results and other factors during the third quarter of 2023.