TRX Gold Corporation is pleased to announce positive assay results from its 19-hole metallurgical variability sampling program on the Buckreef Gold Main Zone.
The results are positive and significant for the Company as they continue to demonstrate: (i) continuity of mineralization down dip and along strike of the deposit; and (ii) excellent width and grade of mineralization.
As part of the upcoming metallurgical variability study, using core from this program, the Company will assess the amenability of the sulphide material to be processed through the existing processing plant, using its relatively simple flowsheet. In turn, this may have positive implications for potential plant expansions.
“The continuity of gold mineralization in the Main Zone is clearly demonstrated by these metallurgical drill hole results – there is a great mine here!” noted Stephen Mullowney, Chief Executive Officer of TRX Gold. “We have demonstrated over the past year our ability to mine and build an ore processing plant that is operating at 1,000+ tpd with 90% gold recoveries. Our next phase will focus on a simple gold recovery circuit for the broader project―the 2.0 million plus ounce Measured and Indicated Mineral Resource, and 0.6 million ounce Inferred Mineral Resource. These assay results provide Buckreef with excellent samples for broader deposit metallurgical testing as continuity is critical for a successful gold mining business. If the metallurgical variability study confirms that we can utilize the current straightforward flowsheet and existing processing plants for further expansions, we would really be off to the races!”
Metallurgical variability program background
TRX Gold will also be evaluating the existing processing plant flowsheet of: (i) crushing; (ii) grinding; (iii) and carbon-in-leach, with primary grinding of P80 = ~75 µm. The operations have achieved gold recovery rates of ~90% since production began in October 2021, with over 100,000 tonnes being processed. SGS Canada Inc. (“SGS”), as part of the initial metallurgical test work at their Lakefield, Ontario facility, achieved a comparable recovery rate for a similar flowsheet as current operations as described below.
During the year, the Company working with Ausenco, revised and elaborated the request for proposal process (for the metallurgical variability study), including studies for dry stack tailing parameters. The Company has identified a number of global laboratories to complete this work, which will encompass the first 5-7 years of production from a larger mine and processing operations at Buckreef Gold. This study will build on the prior work of SGS on deeper parts of the mineral resource and data gathered during processing of the oxide, transitional mineral reserve.
The 18 metallurgical holes reported (of 19 drilled) from Buckreef Gold are designed to intersect gold mineralization between current oxide ore mining and the deeper preliminary metallurgical drill holes in the sulphide deposit reported in 2021 (see Press Release dated June 9, 2021).
SGS was previously retained to complete initial metallurgical test work at their Lakefield, Ontario facility on the sulphide component of the mineral resource. This work was completed in 2021. As part of the initial 2021 study, three diamond core samples taken from the fresh rock (‘sulphide’ mineral resource) of the Buckreef Gold deposit were submitted to SGS Lakefield for the study. In addition to the straightforward flowsheet reported in the June 9, 2021 Press Release, SGS also evaluated a flowsheet which is similar to Buckreef Gold’s flowsheet in current operations. The additional flowsheet SGS evaluated consisted of: (i) gravity separation and (ii) cyanide leaching.
Maximum gravity + cyanidation leach gold recoveries for MC-1, MC-2, and MC-3 were ~88%, ~89%, and ~79%, respectively, at P80’s in the ~75-80 μm range. This is similar to the grind size and recovery rates achieved in current operations over the past year. Composites MC-1 and MC-2 demonstrated a very similar metallurgical response despite the extreme grade differences between the samples. As disclosed in the June 21, 2021 Press Release, further opportunities to improve gold extraction from MC-3 have been identified through diagnostic leach testing.
In the initial metallurgical test work, gravity separation at a grind size between ~144-152 μm represented a low proportion of overall gold recovery, representing 4.2%, 4.2% and 4.4% for MC-1, MC-2, and MC-3 respectively. It is the Company’s view that given the low recovery of gravity separation, it would not make sense to add this (a gravity circuit) to a flowsheet as the majority of the gold recovered in the gravity separation process would be recovered in the cyanide leaching process.
As reported in the June 21, 2021 Press Release, recovery rates of 94.1%, 95.4% and 85.3% were achieved for MC-1, MC-2, and MC-3 respectively, from the straightforward flowsheet as follows: (i) primary grinding to P80 = ~100-150 µm; (ii) rougher flotation; (iii) regrind of the rougher concentrate to ~15-20 µm (P80); (iv) cyanide leaching of the reground flotation concentrate and (v) cyanide leaching of the flotation tailing.
It is important to note other highlights from the initial metallurgical test work include: (i) no refractory association of gold with arsenic sulphide was detected; (ii) the samples tested did not exhibit any preg-robbing or other refractory characteristics; and (iii) clean tailings with a high probability of mine tailings not being acid generating, thus confirming the potential approach for dry stack tailings in the future.
Sample Protocol QA/QC
The sample chain of custody is managed by the Buckreef geology team on site. Reported results are from diamond drilled core samples. Intervals of core to be analyzed are split into half using a mechanized core cutter, with one half sent to the Laboratory for geochemical analysis and the remaining half kept in storage for future reference and uses. Diamond drilled core has been a HQ size and recoveries are consistently 100% across all drill holes intercept reported.
Sampling and analytical procedures are subject to a comprehensive quality assurance and quality control program. The QAQC program involves insertion of duplicate samples, blanks and certified reference materials in the sample stream. Gold analyses are performed by standard fire assaying protocols using a 50-gram charge with atomic absorption (AAS) finish and a gravimetric finish performed for assays greater than 10 grams per tonne.
Sample Preparation and analysis are performed by independent SGS Laboratory in Mwanza, Tanzania. SGS Laboratory is ISO17025 accredited and employs a Laboratory Information Management System for sample tracking, quality control and reporting.
The metallurgical drill hole intersections reported here are down-hole length and may not represent true width. The drilling objective was to intersect the orebody in oblique/acute angles to maximize samples weights for metallurgical test work, and to test the down-dip continuity of gold mineralization. The true width is estimated at approximately 30% of drilled length.
