Highlights from the metallurgical testing include:
- Comminution tests indicate a Bond Work Index (BBWi) of 13,5 Kwh/t with medium hardness sulphide and abrasiveness (Ai) of 0.2487
- Cyanide consumption at 0.75 kg/t is a low-medium cyanide consumer and fits into current DFS plant design
- Lime requirement of 0.38 kg/t indicate a very low lime consumption, meaning that operating costs for treating sulphides are expected to be low
“The ongoing results from a comprehensive sulphide metallurgical testing campaign continue to give us great confidence in the amenability of the Kobada sulphides to be treated easily through our existing Gravity and CIL process with very good recoveries. In addition, there appears to be no requirements for any change to the gravity and CIL process circuit to accommodate the sulphides. Work is underway to optimise the grinding requirement of the sulphides versus oxides, and these results are due out soon. This is the best we could have hoped for in terms of optimising the sulphide testwork, and this means that the process plant design already completed to an advanced detailed engineering level can accommodate the sulphides.”
“We are confident that we have a substantial sulphide resource below the oxides, and the results of this testwork will enable us to quickly convert a portion of the existing measured and indicated sulphide resources into reserves. Apart from a huge oxide upside opportunity, the addition of sulphides treatable through our existing plant design adds more value to the size of the Kobada project.”
The comprehensive metallurgical testing program was conducted by Maelgwyn South Africa (MSA) on composite samples from all defined mineral zones (north, south, and central domains) of the main shear zone.
The ongoing sulphide ore testwork program involved the following:
- Optimised cyanidation testwork
- Additional comminution studies to determine optimal grind size and abrasiveness of the ore
Optimised cyanidation testwork
Cyanidation testwork indicates a low to medium cyanide consumption required for high gold dissolution rate. Other projects in the region typically consume between 0.85 – 1.38 kg/t, so this is considered a low cyanide consuming ore.
Test No. | Cyanide Consumption kg/t | Lime Consumption (kg/t) | Gold Dissolution (%) | |
1 | 0.09 | 0.40 | 57.1% | |
2 | 0.27 | 0.40 | 59.1% | |
3 | 0.40 | 0.39 | 71.7% | |
4 | 0.55 | 0.39 | 76.1% | |
5 | 0.75 | 0.38 | 93.4% | |
6 | 1.44 | 0.36 | 93.9% |
Results from comminution testing
- Bond Ball Work Index (“BBWi”) - 13.5 kWh/t
- Bond Abrasion Index (“Ai”) - 0.2847
Property | Soft | Medium | Hard | Very Hard |
BBWi | 7-9 | 9-14 | 14-20 | >20 |
Ai | 0.05 | 0.30 | 0.80 |
Based on these results the sulphide ore at the
Effect of Grind
Gold dissolution tests were conducted on gravity middlings and tails by varying grinds 75 to 212 µm as shown in the table below. It can be noted that dissolution of gravity middlings and tails reduced with an increase in grind size - results are in line with expectations.
Grind P80 (µm) | Feed Grade (g/t) | Gravity Tails Recovery (%) | Gravity Conc Dissolution (%) | Gravity Tails Dissolution (%) | Combined Dissolution (%) | Cyanide (kg/t) | Lime (kg/t) | ||||
212 | 0.54 | 41.46% | 96.37% | 50.65% | 70.37% | 1.20 | 0.22 | ||||
150 | 0.54 | 41.46% | 96.37% | 66.52% | 79.90% | 1.18 | 0.21 | ||||
106 | 0.54 | 41.46% | 96.37% | 89.14% | 93.48% | 1.44 | 0.2 | ||||
75 | 0.54 | 41.46% | 96.37% | 93.55% | 96.13% | 2.38 | 0.24 |
Further optimisation work from OMC will determine any possible changes to mill design to support finer grinding, however the rest of the process plant design can accommodate the sulphides without any further design changes. In addition, additional variability testing will take place over the next few weeks.
Corporate Update
The company would like to announce some structural corporate changes to its senior management team and office services agreement.
The Company would like to welcome
Additionally, the Company would like to announce that it has agreed to part ways with
The Company also announces that it has terminated its services agreement at
Option Grant
The Company has granted a total of 2,800,000 stock options to certain officers, directors and consultants of the Company pursuant to the Company’s stock option plan. The stock options vest immediately and may be exercised at a price of
About
For more information:
President and Chief Executive Officer
+(27) 76 411 3803
Danny.Callow@africangoldgroup.com
Non-Executive Chairman of the Board
(604) 722-5381
Scott.Eldridge@africangoldgroup.com
Daniyal Baizak
VP Corporate Development
(647) 835-9617
Daniyal.Baizak@africangoldgroup.com
Camarco (Financial PR)
+44 (0) 20 3757 4997
AfricanGoldGroup@camarco.co.uk
Cautionary statements
This press release contains “forward-looking information” within the meaning of applicable Canadian securities legislation. Forward-looking information includes, but is not limited to, statements regarding, processing of sulphide materials, appointment of officers and the grant of incentive stock options. Generally, forward-looking information can be identified by the use of forward-looking terminology such as “plans”, “expects” or “does not expect”, “is expected”, “budget”, “scheduled”, “estimates”, “forecasts”, “intends”, “anticipates” or “does not anticipate”, or “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might” or “will be taken”, “occur” or “be achieved”. Forward-looking information is subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of AGG to be materially different from those expressed or implied by such forward-looking information, including but not limited to: receipt of necessary approvals; general business, economic, competitive, political and social uncertainties; future prices of mineral prices; accidents, labour disputes and shortages and other risks of the mining industry. Although AGG has attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking information. AGG does not undertake to update any forward-looking information, except in accordance with applicable securities laws.
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