Pilot Testing Of Rapid Oxidative Leach Technology At Caribou

VANCOUVER - Trevali Mining Corporation reported that a pilot plant testing program using Caribou run-of-mine and milled material at FLSmidth's Rapid Oxidative Leach (ROL) process testing facility in Salt Lake City, Utah, is underway. The program expands on previous laboratory test work and is aimed at demonstrating the potential to recover zinc, lead, copper, gold, and silver as a precipitate or metal and additional zinc and lead from Caribou ore and mill tailings.

Highlights: Leach test program targets an improvement to zinc, lead, copper, gold, and silver metal recoveries; Potential to produce a precipitate or metal on site replacing the current ore concentrate that is produced at Caribou, which, if implemented, would lead to savings on transport costs and offsite treatment costs; Opportunity to process historic mill tailings, which include gold and copper metals, in addition to run of mine ore, increasing revenues and reducing closure liabilities; Potential to reduce Trevali's carbon footprint at Caribou; Potential to extend Caribou's mine life and treat lower-grade deposits in the Bathurst camp; and A successful pilot plant test program is expected to support future study work on a Preliminary Economic Assessment and NI-43-101 Technical Report which includes potential processing of the Trevali mill feed and mill tailings and production of metal on site.

If the pilot plant testing program indicates that the ROL technology has the potential to be successfully implemented at Caribou, it may allow Trevali to replace the existing flotation circuit at Caribou with atmospheric leach vessels and potentially an SX/EW train, introducing the possibility of producing base and precious metals on-site and thereby save transport costs and offsite treatment costs. The initiative is consistent with Trevali's strategy to extend the two-year mine plan and investigate further longer-term value-enhancing opportunities in the Bathurst Mining Camp. In addition, the technology has the potential to reduce the Company's carbon footprint and provide other sustainable environmental benefits via the re-treatment and disposal of tailings.

Conceptual objectives of the program include: Recovery of metals/minerals that are not recoverable utilizing the current technology at Caribou (precious metals and magnetite); and Improved payables/selectivity of the traditional flotation process utilizing new and emerging technologies.

"FLSmidth's Rapid Oxidative Leach metallurgical technology has the potential to transform the Caribou mine and the wider Bathurst Mining Camp. If viable at Caribou, the technology may increase metallurgical recoveries, produce precipitate or metal on site, including copper and gold, and reduce or eliminate freight costs and treatment charges related to concentrate. This next phase of the testing program is an essential step in evaluating the suitability and economic viability of a processing solution with the potential to enhance the value of the in-situ material and tailings at Caribou as well as the surrounding deposits in the Bathurst region," said, Ricus Grimbeek, President and Chief Executive Officer. "The positive results to date support further study and analysis given the potential implications for the Bathurst Mining Camp in general and Trevali in particular."

Beyond quantifying the ability to recover additional metal values, the objective for the pilot plant test program is to determine the various kinetic factors, mass and energy balance, and engineering data to support future engineering on a Preliminary Economic Assessment for potential processing of the Trevali mill feed and mill tailings and produce metal on site. Continuous pilot plant trials commenced in June 2021 (Phase 1) to tune the pilot plant and provide material for precious metal leach tests in late July, followed by a test program at the Caribou Mine site that is planned for September 2021 (Phase 2). Leach data and results are expected to verify that batch testing results can be achieved in a continuous operation.