Golden Deeps Limited (ASX:GED) has upgraded the concentrate grade of stockpiled ore at its Abenab vanadium, lead and zinc project in north-eastern Namibia, securing its pathway to production.
The results of metallurgical test work confirm the above-ground stockpiles can be used for initial operations at Abenab in advance of the below ground mineral resource.
Early cash flow
Golden Deeps executive chairman Michael Minosora said identifying above ground stockpiles as amenable to simple gravity separation and producing a significantly upgraded concentrate was a huge milestone for the company.
He added: “This has the potential to reduce the time to production for the Abenab project by 12 months, generating early cash flow for the operations while the below ground mineral resource is developed.”
Consistency across higher and lower head grades
The separation process identified that a three-stage rougher circuit, followed by a three-stage scavenger circuit, provided the best overall concentrate grades.
This final bulk concentrate sample was 8.9% vanadium, 30.5% lead and 8.95% zinc, indicating the capability to achieve more than 19% vanadium grades from the main ore body.
Additional recovery options including optimising the final design, selecting appropriate spiral and separation technology are being planned.
Potential vanadium concentrate grade more than 19%
The results are in line with, if not better than, previously reported Avonlea test work undertaken on Abenab ore with a much higher starting grade and using less stages of separation.
Assuming an upgrade factor of 30 can be applied to the main orebody which has a starting grade of 0.66%, a concentrate grade of more than 19% vanadium pentoxide would be expected utilising a similar flowsheet design.
Simplified approvals process
Minosora continued: “The company has been advised by the Namibian Ministry of Mines and Energy that the processing of the above ground stockpiles will not require a full mining licence and that a simplified plant scope works approval could be utilised.
“This has the benefit of reducing the approvals process and further reducing the development timeline to production.”
Grade and recovery improvements at each stage
Using a simple de-sliming hydro cyclone, the gravity separation test successfully rejected 40% of the fine material with only a 6% loss of total vanadium to reject.
The primary and secondary spiral separations showed definitive signs of upgradability at each successive separation stage on the concentrate stream.
Grade and/or recovery improvements were further noted with tertiary cleaning and the use of a scavenger circuit on the tailings achieving a vanadium upgrade near to 30 times the starting head grade.
Another benefit of the test work is proving the use of density measurement as a suitable process control method.
To reduce cost and time, density assessment of the material was investigated as an alternative for full chemical analysis.
This has proven very successful with a correlation of 99.6% and creates a significant opportunity for simplified process control within an operating plant,