Fireweed Zinc Ltd. (TSXV:FWZ) is pleased to announce positive results from metallurgical tests conducted as part of the Preliminary Economic Assessment (“PEA”) work underway for the Macmillan Pass Zinc Project, Yukon. Base Metallurgical Laboratories of Kamloops, BC, performed the test work under supervision by Fireweed’s PEA contractor, JDS Energy and Mining, Inc. (“JDS”).


  • Excellent metallurgical results based on the most extensive and representative work to date.
  • The “global” composite zinc concentrate graded 58% Zn at 89% Zn recovery. The “global” lead concentrate contained 61% Pb at 75% Pb recovery.
  • The zinc results compare favorably to a 2012 test program which resulted in concentrate containing 58% Zn at 80% recovery.
  • High quality, low iron concentrate is expected to be attractive to smelters.

“The results give us confidence that the Macmillan Pass project will produce concentrates desirable to potential traders and global smelter customers,” commented Brandon Macdonald, CEO. “These results confirm and improve upon past metallurgical studies and will help inform the economics in our upcoming PEA. We expect to announce PEA results in the coming weeks.”

Table 1. Summary of Macmillan Pass Global (65% Tom + 35% Jason) Composite Metallurgical Results
Product Grade Metal Recoveries (%)
Zinc % Lead % Silver g/t Lead Zinc Silver
Feed 7.3 3.2 44 100 100 100
Lead Concentrate* 8.9 61.5 688 75 5 59
Zinc Concentrate* 58.4 2.2 88 7 89 22
*Note: Lead and Zinc are a weighted average from Lock Cycle Tests BL0236 LCT45 cycles D&E

Description of Metallurgical Test Work

This new work not only extended coverage into previously untested deposit zones, but also included test procedures, such as dense media separation (DMS) tests, not undertaken in prior programs.

Core were selected from eight drill holes spatially, mineralogically and grade representative of the known deposit zones. Drill core was large, HQ size core (61.1 mm (2.4 inch) diameter). Total sample weight was 553.5 kg (1,220 lbs), including 5% hanging-wall and footwall waste rock dilution.

For the first phase of testing, the eight core were combined into five composite samples: two from the Tom West zone, one from Tom East and two from Jason Main. This phase included mineralogy, comminution and flotation tests.

A second set of three composites was then prepared from the five phase one composites. These three composites represent both the major deposits, Tom (combined West and East), Jason Main, and a “global” sample made up of a 65% Tom and 35% Jason blend, representative of the total projected project production across both deposits. This second set of composite samples underwent locked cycle testing to determine recovery and concentrate grades close to what would be expected in an operating plant. Analyses for other elements in the concentrates, and tailing filtration tests, were also completed.


Tests revealed acceptable liberation of sphalerite and galena at a primary grind of P80 50 µm (80% passing through a 50 micron mesh).


Comminution test work determined the grinding energy required to liberate lead and zinc minerals prior to flotation, and abrasion testing to determine mill and grinding media wear characteristics:

  • The composites tested had SAG Circuit Specific Energy (SCSE) values of 7.82 and 9.2 kWh/t.
  • Bond ball mill work index (BWi) tests at a sieve size of 106 µm showed the material to be moderately soft with BWi values ranging from 8.8 to 14.0 kWh/t.
  • Abrasion index results averaged 0.27 g.

These low specific energy and bond work indices predict relatively low energy consumption for grinding.

Locked Cycle Testing (LCT)

LCT simulates a continuous, stable, processing plant flotation circuit. The LCT employed a conventional flotation flowsheet at a target primary grind size of P80 50 µm. Regrinding was included in both the lead and zinc circuits, with grind sizes of 15 µm and 25 µm respectively. The LCT45 results for the global blend sample had an average lead concentrate grade of 61% Pb at 75% Pb recovery, and an average zinc concentrate grade of 58% Zn at 89% Zn recovery.

Other Elements

The iron levels are low, at about 1.5%, a feature desired by zinc smelters.  Deleterious element levels were generally low, except for mercury at 155 ppm and silica at 4% in the global zinc concentrate. Either or both may incur modest smelter penalties.  See Appendix for values of other elements in concentrates.


The Tom and Jason deposits reacted well to conventional flotation concentration pro