Pure Gold announces excellent gold recoveries at Madsen
Wednesday, Apr 04, 2018
  • High gold recoveries from samples tested average 95.4%, with a range from 90% to 99%, and an average of 36% reporting to the gravity circuit
  • Preliminary gold recovery in the 8 Zone exceeds 99%
  • All tests show low reagent consumption

Pure Gold Mining Inc. is pleased to report preliminary metallurgical test results which form part of the ongoing Definitive Feasibility Study for the high grade Madsen Gold Project, Red Lake, Ontario (“Madsen”).  These results are part of a comprehensive ongoing metallurgical program designed to define the processing parameters, establish grade-recovery relationships and to optimize gold recovery for the existing Madsen milling circuit.  Importantly, results herein are consistent with the excellent historical production recoveries achieved at Madsen and open potential opportunities for further optimization.

In addition to returning high gold recoveries, with a material proportion of the gold reporting to the gravity circuit, the preliminary results demonstrate low reagent consumptions with an arithmetic average of 0.63 kg/t sodium cyanide and 0.25 kg/t lime. The average Bond mill work index of the 12 composites tested was 14.5 kWh/t.

“These results provide very strong support for an improvement on the more conservative recovery estimates employed in our PEA of 92%, and are very much in line with the higher recoveries realized from 36 years of continuous historical production at Madsen1,” states Ken Donner, Vice President Operations for Pure Gold. “These initial tests were run using historical operating parameters to provide a baseline for further optimization tests aimed at improving recoveries from all zones.”

Darin Labrenz, President and CEO commented: “As expected, metallurgical test results confirm that Madsen should return outstanding gold recoveries with a significant amount of free gold reporting to the gravity circuit.  We are particularly encouraged by the strong metallurgical response returned from the high grade 8 Zone, with gold recoveries of over 99% with 82% reporting to gravity.  Combined with the lower reagent consumption, and a moderate bond ball mill work index, these results highlight an opportunity for significant improvement of processing parameters in our ongoing feasibility study.”

Phase 2 of the test program will be completed on global samples based on the feasibility mine production schedule. These tests will aim to optimize the flowsheet and reagent scheme over the life-of-mine plan, and define the cyanide destruction parameters for the tailings outflow. In addition, further refinement of gravity recoverable gold will be completed as well as carbon loading and oxygen uptake rate tests.


Approximately 1,000 kilograms of drill core were collected from 52 drill hole intercepts distributed throughout the Madsen resource for Phase 1 of Pure Gold’s metallurgical test program. Phase 1 testing includes mineralogy, comminution and gravity-leach recovery tests and was completed at Base Metallurgical Laboratories Ltd (“Basemet”) in Kelowna, BC, under the supervision of JDS Energy & Mining Ltd.

Twelve global composites were generated to create spatially representative samples based on mineralogy, grade and location, within the three main domains of the deposit: Austin, McVeigh and 8 Zone. Austin and McVeigh styles of mineralization are both dominated by disseminated gold mineralization within a broader foliated and altered basalt host rock; whereas, 8 Zone mineralization is distinctively higher grade and predominantly quartz vein-hosted within altered basalt and ultramafic rocks.

The arithmetic average gold recovery for the samples tested is excellent at 95.4% Au, with individual composites ranging from 90.5% to 99.9% gold recovery at a primary grind size of P80 75 microns. Gravity concentrate gold recoveries are especially high, with an average of 36.3% and range up to 82.3% gold recovery in the 8 Zone domain. Overall, cyanide and lime consumptions are considered low to very low at 0.63 kg/t and 0.25 kg/t, respectively.

Composite Mineralogy and Comminution Tests

The Austin and McVeigh domain composites consist of variably altered and silicified basalt, with quartz content averaging 18%.  While silica is a consistently elevated component of high-grade gold mineralization at Madsen, sulphide minerals (predominantly pyrrhotite and pyrite) have relatively low modal concentrations averaging 2.7% and do not correlate well with gold. The 8 Zone composite is characterized by a moderately altered pyroxenite host rock cut by swarms of millimeter-scale quartz veins.

Overall, the samples tested exhibited soft to moderate hardness with Bond ball mill work index values, at P80 of 106 microns, ranging from 9.7 for the 8 Zone composite, to 17.1 in the strongly silicified Austin composite.


The Madsen Gold Project has historical production of 2.5 million ounces of gold and a current indicated resource of 1,744,000 ounces gold at 8.7 g/t gold (in 6.2 million tonnes) and an inferred resource of 296,000 ounces gold at 7.9 g/t gold (in 1.2 million tonnes), the Project benefits from existing infrastructure including a mill and tailings facility, paved highway access, and access to power, water and experienced labour. A feasibility study is underway with results expected in the fourth quarter of 2018 and the Madsen Gold Project is firmly on the path to becoming Ontario’s next gold mine.

For more information, please visit: http://puregoldmining.ca

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