Kenorland Minerals releases additional metallurgical results at Frotet Project

Kenorland Minerals Ltd. has announced the results of additional metallurgical testing of the Regnault gold system on the Frotet Project, located in northern Quebec and held under joint venture with Sumitomo Metal Mining Canada Ltd. 

Metallurgical study highlights include: 

• Optimized recoveries of up to 93.3% Au and 90.5% Ag for whole ore leaching

Results of the Additional Metallurgical Study

A preliminary metallurgical study at Regnault was initiated in July 2022 with the completion of drill hole 22RDD149 (29.20m at 16.61 g/t Au including 9.85m at 44.89 g/t Au*). The objective was to characterise the amenability of cyanide extraction of Au and Ag. Results of the study, summarised in a press release dated January 18, 2023, indicated promising Au-Ag recoveries, and identified additional steps to further maximize recovery. The follow up study investigated the effects of gravity separation prior to cyanide leaching, flotation prior to cyanide leaching, finer grinding, and the use of an activator to increase reaction kinetics during cyanide leaching. (*See press release dated November 14, 2022).

When comparing the different flowsheet options investigated for the Regnault style ore, the highest recoveries were realized with optimized whole ore leaching, with 93.3% Au and 90.5% Ag recovered. Combined gravity separation and cyanide leaching were 90.0% for Au and 90.6% Ag. Flotation testing when combined with gravity separation and cyanide leaching were lower than whole ore leaching, at 83.7% Au and 82.1% Ag. Compared to the whole ore leaching process the amount of cyanide contact material that would be reduced by flotation is 5.8% and cyanide consumption is reduced by 65.0%. These results indicate that the Regnault style ore is amenable to conventional cyanide leaching with recoveries of up to 93.3% Au and 90.5% Ag.

Details of the Metallurgical Study

Material from the original program (27.1m of NQ half drill core from 22RDD149) was used for the additional testing. Samples were crushed to under 1.7mm and thoroughly mixed. 1kg samples were split for head assay and various metallurgical testing. The composite head grade was 15.9 g/t Au and 24 g/t Ag. Mineral liberation analysis (MLA) identified gold-silver-telluride, electrum and native gold as the main gold and silver bearing mineral species.

The effects of grinding size on whole ore leaching from the preliminary study showed the highest Au recoveries (up to 89.9%) when decreasing grind size from baseline 100µm to 75µm. Testing from the follow up study reduced grind size to 50µm, increasing recoveries up to 91.8% for Au and 76.3% for Ag.

Whole ore leaching targeting 100µm grind size with the addition of extraction accelerators lead nitrate, sodium citrate, and slaked lime were investigated to improve reaction kinetics. Compared to baseline conditions, addition of sodium citrate increased Au recovery to 88.4% while the other reagents did not increase Au recoveries. Addition of any of the three accelerators resulted in increased Ag recovery, ranging from 71.9-85.0%. 

Parameters of the whole ore leaching process that showed the most promise for maximizing recoveries were combined. Testing targeted 50µm in P80 grind size, leaching duration of 72hrs, 1.0 g/L NaCN concentration, increased pH of 12.5, dissolved oxygen content of 33-38 mg/L and addition of sodium citrate as an accelerator. This resulted in recoveries of 93.3% Au and 90.5% Ag, a marked increase when compared to initial study baseline conditions of 85.0-88.7% Au and 63.2-69.8% Ag.

Tags: Quebec / Exploration / Gold / All Articles