Development

SGS Canada Inc. (SGS) was retained to complete initial metallurgical test work at their Lakefield facility on the sulphide component of the mineral resource. SGS flowsheets will be a cornerstone of the feasibility study and help prove the viability of the project to financiers and stakeholders as Buckreef progresses towards full operation. SGS has reviewed the information in the press release. The initial metallurgical test work is now concluding. SGS has now been commissioned to undertake the metallurgical variability phase for Buckreef.

Highlights

  • Three diamond drill core samples were taken from the fresh rock (‘sulphide’ mineral resource) of the Buckreef deposit for the purposes of metallurgical test work. The following intercepts and gold recovery rates were observed (see figure on the subsequent page):
    • MC01: 0.54 g/t over 78.88m – 94.1%
    • MC02: 19.4 g/t over 27.99m – 95.4%
    • MC03: 1.71 g/t over 52.53m – 85.3%
  • SGS have advised that a flowsheet consisting of crush/grind and flotation followed by regrinding of the rougher concentrate and cyanidation at site, along with cyanidation of the flotation tailing is currently the metallurgically optimal mill circuit. Dore will be produced at site.
  • Test work is ongoing on the MC03 sample, for the purpose of improving the gold recovery rate. The same test work can be applied to the MC01 and MC02 samples.
  • SGS have now been commissioned to complete feasibility level metallurgical testing that will focus on the first 5-7 years of production at Buckreef.

Mr. Stephen Mullowney, CEO (TanGold) commented, “the initial metallurgical results from a reputable and prestigious organization (SGS Lakefield) have indicated that a well-known and simple flowsheet for our large high-grade deposit and plant is most likely. The initial recoveries are excellent, and I look forward with confidence to the results of the variability testing."

Mr. Andrew Cheatle, COO (TanGold) added, “the initial metallurgical recovery results are excellent and typical of Archean shear zone type hosted gold deposits. These results also firmly underscore our overall plan to have two plants with two different flowsheets; one plant to treat gold bearing oxides and a second plant to treat gold bearing sulphide or primary materials. We look forward to continuing to work with SGS on the metallurgical study.”

Further Details of Test Work

In 2020, three diamond drill holes were completed for the purposes of initial, modern era metallurgical test work. Diamond drill hole details are tabulated below:

The samples were extracted as fresh drill core samples from areas/zones with known lithologies from within the current projects open pit limit. The samples were selected by TanGold and confirmed by the SGS geological services group that worked together doing the metallurgical sample selection. The investigation included ore characterization, comminution, mineralogy, head analyses, and potential for gold preg robbing, and evaluated the amenability of the three samples to two primary processing flowsheet options, that incorporate comminution (crushing and grinding), gravity separation, flotation and cyanidation unit operations. A high-level summary of the test work is provided below:

  • Bond ball mill work index values were 18.3 and 18.5 in MC01 and MC02 respectively. MC03 was slightly softer at 17.1. The hanging wall (HW) comp was at 17.1 and the foot wall (FW) was 18. All of these comminution samples are classified as “Hard” when compared to the SGS comminution database. All of these samples are somewhat softer than the values indicated for Buckreef ore as seen in the historical documentation.
  • Gravity separation testwork completed to date by SGS has indicated poor gold recoveries, averaging just under 5%. This seems to conflict somewhat with indications in the historical testwork records which indicated potential gold recoveries of >30%.
  • Direct cyanide leaching of the gravity separation tailing indicated that composites MC01 and MC02 yielded ~80% gold extraction at a grind size of ~150 μm (P80). The softer material, MC03, yielded 72% gold extraction at the same approximate grind size. Grinding significantly finer, to ~75 μm (P80), resulted in 8-9% additional gold extraction (to 88-89%) from MC01 and MC02 material. MC03 gold extraction increased to 79% with the same reduction in leach feed size. Tests were run over 48 hours and gold extraction had more-or-less ceased after 24 hours, with only minor additional gold extraction up to 48 hours retention time.
  • Rougher flotation tests were conducted on gravity tailing at grind size P80’s of ~150, ~120 and ~90 μm. Mass pulls of ~13-20% were observed. Sulphide recovery was very stable (97-98%) and showed no impact from coarser/finer grinding. Gold recoveries improved only slightly, in MC01 and MC02 tests, with finer grinding, from ~87-90%. MC03 gold recovery remained rather stable at ~90% across the feed size test series.