Nova Minerals Ltd (ASX:NVA, OTCQB:NVAAF) welcomes “highly encouraging results” from its first phase metallurgical test work on mineralisation from its high-grade RPM North deposit in Alaska.
Leach Tests were conducted at Bureau Veritas Vancouver to determine the potential for intensive leach of gold contained in flotation concentrate.
Results were outstanding. The tests saw 92.4% of gold recovered into a concentrate with 14.3% of the flotation feed mass. A high flotation concentration ratio is important, allowing fine grinding and intensive leaching of a small flotation concentrate, at a reasonable cost.
Test work flotation and leach recoveries were 92.4% and 96.2% respectively. Combined flotation and leach recovery was 88.9% using 73 microns in flotation and 16 microns in leaching.
Concentrate leach recovery was calculated by Bureau Veritas based on gold recovered into solution and gold left in solid tailings.
Solid foundation for improved economics
The company is confident the results set down a solid foundation for improved economics in the Phase 2 scoping study.
The average head grade of the RPM metallurgical composite was 1.34 g/t gold. The overall average tail grade achieved from the composite was less than 0.15 g/t gold.
The tail grades achieved at RPM of less than 0.15 g/t gold are very encouraging. They have allowed the company to optimise the process flowsheet and test work parameters since testing commenced on greater Estelle samples.
Scoping study due later this year
Further test work will be undertaken at head grades that are in line with the expected process plant feed grades emanating from the Phase 2 scoping study, due later this year.
The flow sheet for the test work comprises conventional flotation concentrate followed by fine grind cyanide leaching.
Test work continues across all the Estelle Gold Trend deposits for inclusion in the PFS due late 2023, which will include the RPM North, RPM South, and the Korbel Deposits.
RPM continues to deliver thick high-grade interceptions with drill hole RPM-008 recently returning 140 metres @ 6.5 g/t gold, on the back of the previous announced RPM-005 discovery hole of 132 metres @ 10.1 g/t gold.
Continuous flow of drill results from the ongoing Korbel and RPM programs to be reported throughout the year, as assay results become available from the laboratory.
“The new metallurgical test work from the RPM Deposit at Estelle continues to demonstrate encouraging gold recoveries on the high-grade deposit using composite samples of only 1.34 g/t,” Nova CEO Christopher Gerteisen said.
“These results from RPM are a significant improvement on the positive results already achieved from the Korbel Deposit and harmonised with the existing flowsheet.
“The consistently low tail grades achieved in test work at RPM will be carried through into the project studies and evaluations.
“Metallurgical test work continues to provide confidence with improved high recovery and we expect to achieve CAPEX and OPEX savings in fine grinding and leaching circuits.
“The Phase 2 scoping study is a further snapshot in time and further test work and trade off studies will optimise capital, operating costs, recoveries and operability to enable the company to select the optimum route for the project to make the most money and demonstrate the highest NPV in the PFS, with ABH Engineering and Whittle Consulting working in tandem to find the optimum.”