Last checked at 24 Sep 2020 07:00
Cora Gold Limited / EPIC: CORA.L / Market: AIM / Sector: Mining
24 September 2020
Cora Gold Limited ('Cora', 'Cora Gold' or 'the Company')
Further Positive Metallurgical Testwork Results
Cora Gold Limited, the West African focused gold company, is pleased to announce the metallurgical testwork results from oxide samples taken from its Sanankoro Gold Project in Southern Mali ('Sanankoro' or 'the Project'). These results follow on from previous work reported on 21 October 2019. The purpose of this testwork was to advance the previous testwork and assess the impact of reagent consumption, residence time, gravity recovery and grind size.
Highlights
94.1% average overall recovery was achieved44% average recovery from gravityOver 90% leach recoveries within 4 hours leach time demonstrating very quick kinetics and significantly shorter than previous testwork programmesCyanide consumption was varied with an average consumption of 0.17kg/tsignificantly less than previous testwork programmesSamples were selected to represent different depth profiles across the oxide deposits of Selin, Zone A and B at Sanankoro279kg of oxide material was tested across the three depositsA gravity and Carbon in Leach ('CIL') flowsheet was used to determine the recovery of gold
Bert Monro, CEO, comments "The results from this metallurgical test programme are excellent. A significant proportion of the gold in the Sanankoro ore can be recovered with gravity with over 90% of the remaining gold leaching from the gravity tails within 4 hours. The quick kinetics should reduce the size of the required leach circuit considerably resulting in a capital saving. Further, a significantly reduced cyanide consumption should also have a favourable impact on operating costs. These results will be used in a trade-off between a conventional gravity & CIL flowsheet and heap leach once ongoing column leach testwork is completed. The outcome from the trade-off will be used as the basis of a definitive feasibility study ('DFS') to commence next year."
Further information
A metallurgical testwork programme was developed at the ALS laboratory in Perth. The purpose of the testwork was to take previous work programmes and to determine the impacts of reducing reagent consumption and reducing residence time through the addition of oxygen, to determine the gravity recovery of each sample, and to understand the effect of grind size.
Samples Tested:
The testwork focused on oxidised ore from the Selin deposit ranging in depth from 12m to 53m and a composite from the Zone A and B deposits ranging in depth from 27m to 91m and consisting of RC chip and core.
Head Grade:
Fire assays were performed on the three composite samples.
Selin average Gold assay - 2.7g/t
Zone A and B average Gold assay - 0.82g/t
Comminution:
A composite sample from Selin and a composite sample from Zone A and B were used to determine the Bond Ball Mill Work Index ('BBWI'). Based on the results the ore can be classified as moderate hardness.
Composite | BBWI (KWhr/t) |
Selin | 12.8 |
Zone A&B | 14.2 |
Gravity Testwork:
A 10kg sample from each area was used on a laboratory scale Knelson concentrator. Two grind sizes were tested to determine the effect of grind size on gold liberation and gravity recovery. A grind size of 75um and 106um were used in the testwork with the following results:
Sample | Recovery % |
Selin 75um | 50.8 |
Selin 106um | 40.8 |
Zone A&B 75um | 44.5 |
Zone A&B 106um | 38.2 |
The results clearly show an increasing gravity recovery trend with a finer in grind size.
CIL leach testwork:
CIL leach testwork was performed on gravity tails. Grinds of 75um and 106um were tested with various cyanide concentrations over a 24-hour period. The table below shows the results.
SAMPLE ID | TEST # | GRIND SIZE (P80 um) | GRAVITY GOLD (%) | TOTAL GOLD EXTRACTION (%) | INITIAL NaCN ADDITION (kg/t) | NaCN CONSUMPTION (kg/t) | LIME CONSUMPTION (kg/t) |
SELIN | JR5758 | 75 | 50.53 | 95.08 | 0.35 | 0.18 | 4.52 |
SELIN | JR5759 | 75 | 50.68 | 95.07 | 0.55 | 0.24 | 4.72 |
SELIN | JR5760 | 75 | 51.10 | 95.41 | 0.70 | 0.26 | 4.51 |
SELIN | JR5856 | 106 | 40.74 | 92.53 | 0.26 | 0.17 | 3.46 |
SELIN | JR5857 | 106 | 40.83 | 91.38 | 0.15 | 0.11 | 3.24 |
ZONE A&B COMBINED | JR5790 | 75 | 46.31 | 98.47 | 0.35 | 0.14 | 0.57 |
ZONE A&B COMBINED | JR5791 | 75 | 44.65 | 98.03 | 0.55 | 0.21 | 0.49 |
ZONE A&B COMBINED | JR5792 | 75 | 42.62 | 98.82 | 0.70 | 0.22 | 0.50 |
ZONE A&B COMBINED | JR5858 | 106 | 36.41 | 83.83 | 0.26 | 0.08 | 0.62 |
ZONE A&B COMBINED | JR5859 | 106 | 40.04 | 93.04 | 0.15 | 0.08 | 0.62 |
All leach tests gave a minimum 90% recovery after 4 hours. Oxygen was initially added to all samples at 12ppm and maintained above 10ppm for the duration of the tests.
Heap leach work is also currently underway, and results will be announced in the coming months once tests have been completed. Both sets of metallurgical results will be used to consider a trade-off exercise for a flowsheet selection which will achieve the greatest economic outcome for the Company.
Market Abuse Regulation ("MAR") Disclosure
Certain information contained in this announcement would have been deemed inside information for the purposes of Article 7 of Regulation (EU) No 596/2014 until the release of this announcement.
Competent persons statement: Mr Russell Bradford, a fellow of AUSIMM, has sufficient experience relevant to the style of mineralisation and type of deposit under consideration, and to the activity which he is undertaking to qualify as a Competent Person in accordance with the guidance note for Mining, Oil & Gas Companies issued by the London Stock Exchange in respect of AIM Companies, which outlines standards of disclosure for mineral projects. Mr Bradford consents to the inclusion in this announcement of the matters based on his information in the form and context in which it appears.
**ENDS**
For further information, please visit http://www.coragold.com or contact:
Bert Monro / Norm Bailie | Cora Gold Limited | +44 (0) 20 3239 0010 |
Christopher Raggett / Charlie Beeson | finnCap Ltd (Nomad & Joint Broker) | +44 (0) 20 7220 0500 |
Andy Thacker | Turner Pope Investments (Joint Broker) | +44 (0) 20 3657 0050 |
Megan Dennison / Susie Geliher | St Brides Partners (Financial PR) | +44 (0) 20 7236 1177 |
Notes
Cora Gold is a gold company focused on two world class gold regions in Mali and Senegal in West Africa. Historical exploration has resulted in the highly prospective Sanankoro Gold Discovery, in addition to multiple, high potential, drill ready gold targets within its broader portfolio. Cora's primary focus is on further developing Sanankoro in the Yanfolila Gold Belt (Southern Mali), which Cora believes has the potential for a standalone mine development. Sanankoro has a positive Scoping Study published on it showing an 107% IRR and US$41.5m NPV8 at a US$1,500 gold price. Cora's highly experienced management team has a proven track record in making multi-million-ounce gold discoveries, which have been developed into operating mines.