Nordic Resources (ASX:NNL) completes initial Kopsa metallurgical testing
Nordic Resources has completed initial metallurgical testing at its Kopsa gold and copper project in Finland.
The program tested 11 mineralised samples using a conventional grinding, flotation and leach process, with locked cycle tests returning gold recoveries of 90% from Stockwork material and 86% from Tonalite material.
Nordic intends to incorporate the results into an updated Kopsa Mineral Resource Estimate during October.
Highlights
Locked cycle copper recoveries reached 91% for Stockwork and 88% for Tonalite material.
Silver recoveries were 76% and 82% respectively.
The initial copper flotation step produced concentrates containing gold and silver.
A new 12,000m drilling program has recently commenced at Kopsa.
Blue Coast Research conducted the testing in Parksville, British Columbia, using 2 samples Nordic selected from higher grade Stockwork mineralisation in Kopsa’s Central Zone and 9 from the more prevalent, lower grade standard Tonalite material.
The samples were chosen to represent the 2 main mineralisation styles and a range of locations across the deposit.
The Stockwork samples averaged 2.01g/t gold, 0.20% copper and 3.4g/t silver, while the Tonalite samples, based on Nordic’s core assays, ranged from 0.46g/t to 0.99g/t gold and averaged 0.74g/t gold, 0.16% copper and 2.5g/t silver.
Gold recovery in the variability tests averaged 90% for Stockwork and 88% for Tonalite, using a process that begins with primary grinding and copper flotation, followed by bulk sulphide flotation.
The bulk sulphide concentrate is reground before leaching, while the announcement reports that the tailings stream from that flotation stage also leaches well.
In the locked cycle tests, the initial flotation step recovered copper alongside some of the gold and silver; subsequent leaching produced the remainder of the recoverable gold and silver as doré.
The Stockwork locked cycle test produced a concentrate grading 24% copper, 115g/t gold and 301g/t silver, while the Tonalite concentrate graded 25% copper, 42g/t gold and 260g/t silver.
Nordic reported that deleterious elements in the concentrates were below smelter rejection limits, while noting that arsenic levels could attract modest penalty charges.
Nordic Managing Director Robert Wrixon said:
“These results represent an important milestone for the Kopsa Project.”
Comminution testing found the Kopsa material reasonably hard and abrasive, while the announcement says it is considered amenable to semi autogenous milling; the reported tests used a primary grind of 80% passing 70 microns.
Nordic expects its next phase of metallurgical work to include further variability testing, mineralogy, comminution, flotation and leaching, as well as an assessment of finer primary grinds.
Kopsa’s existing Mineral Resource is 23.2Mt at 1.09g/t gold equivalent for 814,800oz gold equivalent across Measured, Indicated and Inferred categories.
That estimate uses an existing gold equivalent formula and does not yet incorporate the metallurgical results reported in this announcement or the 9,631m drilled at Kopsa in the past year.
Nordic intends to include both in the planned resource update, while the recently commenced drilling program continues work at the project.