Property: O'Brien 637 ha
Location: Rouyn-Noranda, Qc Canada
Stage: Advanced exploration
Milling: Five (5) potential plants for custom milling within 75 km of the project*
*See metallurgical testing section below
The O’Brien project is located in the Abitibi region in northwestern Québec, on provincial highway 117, about halfway between the towns of Rouyn-Noranda and Val-d’Or. Gravel roads provide easy access to the project.
The O’Brien project is located in the central part of Cadillac Township, Abitibi, in the heart of one of the most productive gold mining camps in Canada, the Cadillac Mining Camp, which boasts over 45 million ounces of gold (produced and in reserves and resources) and 3 mines presently in commercial production.
Table 3. Sensitivity Analysis O’Brien gold project Mineral Resource Estimate, March 2, 2023
|Cut-off Grade||Indicated resources||Inferred resources|
|Tonnage (t)||Grade (g/t Au)||Metal (oz Au)||Tonnage (t)||Grade (g/t Au)||Metal (oz Au)|
|6.0 g/t Au||1,012,000||12.80||417,000||945,000||11.12||338,000|
|5.0 g/t Au||1,313,000||11.12||470,000||1,334,000||9.46||406,000|
|4.5 g/t Au||1,517,000||10.26||501,000||1,616,000||8.64||449,000|
|4.0 g/t Au||1,770,000||9.40||535,000||2,007,000||7.78||502,000|
|3.5 g/t Au||2,065,000||8.59||571,000||2,522,000||6.96||564,000|
|3.0 g/t Au||2,118,000||8.46||576,000||3,668,000||5.79||683,000|
Historical inferred mineral resourcesCharlton, 1995
|Desposit||Short tons||Grade (oz/st)||Ounces|
|Old O'Brien mine||539 327||0,21||110 786|
- *These “resources” are historical in nature and should not be relied upon. It is unlikely they conform to current NI 43-101 criteria or to CIM Standards and Definitions, and they have not been verified to determine their relevance or reliability. They are included in this section for illustrative purposes only and should not be disclosed out of context.
Longitudinal section - O'Brien Project
Metallurgical testing 36E area - 2014
is the average grade obtained from the sample used for testing
average recovery of the gold contained in the ore by gravity concentration
Total recovery achieved by combining flotation or cyanidation with gravity concentration
The material used for the metallurgical testing was pulp from 36E area drill core. It consisted of composite core lengths from the main structures of 36E area (structures No. 1–6 and 8). The sample totalled 61 kilograms and had an average grade of 7.26 g/mt (0.212 oz/st) Au. Therefore, the grade of the material selected for metallurgical testing was very similar to the grade of the resource categories.
However, the average grade of gold recovered from the material tested was 11.13 g/t Au, with variations ranging from 7.47 to 14.59 g/t, which is nearly 56% higher than the grade of the sample prepared for these tests. Given the large amount of free gold in the sample used, the nugget effect may be responsible for this significant difference.
A first series of tests studied metallurgical recoveries that could be achieved with gravity separation. These tests produced a concentrate grading from 18,158 to 20,968 g/t Au, with recoveries in the order of 50–60% of the gold from the ore. The degree of grinding ranged from 58 to 80% minus 200 mesh; recovery improved as the grind became finer.
Potential plants for custom milling
|Mill||Company||Process||Capacity (TPD)||Distance (km)|
|LaRonde||Agnico Eagle||Gravity concentration and Leaching||7 200 |
1 500 (Lapa)
|Westwood||IAMGOLD||Gravity circuit and Carbon-in-pulp||2 200|
|Camflo||Yamana Gold||Leaching / Merrill-Crowe||1200||40|
|Lac Herbin||Eldorado (O3 option)||Flotation and Leaching||1200||75|
|Beacon||Monarques Gold||Leaching / Merrill-Crowe||900||77|
Subsequently, two processing circuits were considered. First, gravity concentration (Knelson concentrator and Mozley table) followed by flotation of the pulp of this concentrate in open and closed circuits. Gravity concentration produced a concentrate grading from 10,263 to 62,143 g/t Au, recovering from 54–67% of the gold from the ore. Flotation produced a concentrate grading 91 to 120 g/t Au. For most of these tests, a total recovery (gravity concentration and flotation) in the order of 93% to 94% was achieved. Some concentrates were analyzed for arsenic, producing results of about 12% As.
The second circuit consisted of gravity concentration (Knelson concentrator and Mozley table) followed by cyanidation of the pulp of this concentrate. Gravity concentration produced a concentrate grading from 25,598 to 30,508 g/t Au, recovering from 58–60% of the gold from the ore. A total recovery (gravity concentration and cyanidation) ranging from 90% to 93% was thus obtained.
For most tests, the degree of grinding used was 65–66% minus 200 mesh, a grind that is considered fine enough for this type of ore. In addition, reagent consumption, for both flotation and cyanidation, was similar to industry standards.