Rouyn-Noranda, Quebec, August 26, 2014: Radisson Mining Resources Inc. (TSXV: RDS) (“Radisson”) is pleased to announce that a series of metallurgical tests performed on ore from Zone 36 East of the O’Brien project has just been completed in the laboratories of the Unité de recherche et de service en technologie minérale de l’Abitibi-Témiscamingue (URSTM) (Abitibi- Témiscamingue mineral technology research and service unit) in Rouyn-Noranda.
Highlights
- 11.13 grams per tonne is the average grade obtained from the sample used for testing
- Average recovery of 59.2% of the gold contained in the ore by gravity concentration calculated from the twelve (12) gravity concentration tests
- Total recovery of 93–94% achieved by combining flotation or cyanidation with gravity concentration
The president of Radisson Mining Resources, Mario Bouchard, said that he was “very satisfied and enthusiastic about the results.”
The material used for the metallurgical testing was pulp from Zone 36 East drill core. It consisted of composite core lengths from the main structures of Zone 36 East (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.
Current NI 43-101 resources, as estimated in 2013 by Roscoe Postle Associates Inc. (RPA) for Zone 36 East (see press release of November 6, 2013) are, for the indicated category, 560,000 short tons at a grade of 0.19 oz/st Au or 6.51 g/mt Au. For the inferred category, they are 317,000 oz/st grading 0.21 oz/st Au or 7.19 g/mt 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.
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.