Metallurgical testing of nickel-cobalt sulphide mineralisation from the Boomerang target at Aston Minerals’ (ASX: ASO) Edleston project in Canada has produced saleable concentrate and strong recoveries.
Early-stage flotation testing of a 30 kilogram sample of ore from the Bardwell prospect within the wider Boomerang target demonstrated that the sulphide mineralogy is amenable to conventional processing techniques.
The head grade of the analysed sample was reported to approximate the overall nickel-cobalt abundance of the entire mineralised interval of 163.5 metres at 0.51% nickel and 0.016% cobalt.
Extremely low levels of nickel in silicate and nickel in oxides were also detected.
Open circuit methods
Testing commenced earlier this year and to-date has only utilised open circuit methods to optimise liberation and floating parameters.
Open circuit work at a grind size of 80% passing 120 micrometres produced a concentrate grade of 11.29% nickel, 0.37% cobalt, 24% sulphur, 38.2% iron and 8.2% magnesium oxide.
Other testing methods to be tried out include different grind sizes and times, recovery from slimes, and upgrade with regrind of concentrate.
Analysis is now underway across lower grade mineralisation to determine beneficiation characteristics.
Aston managing director Dale Ginn said the results received from initial testing were comparable to metallurgical recoveries of some of the world’s more substantial nickel sulphide operations.
“The testing methods we used are all first pass conventional methods of flotation and are by no means optimised … we are incredibly encouraged by the results,” he said.
“We have identified multiple opportunities to improve upon them including coarsening the grind size, grinding after flotation and using magnetic separation of the slimes produced from primary crushing.”
The Edleston project is located within Canada’s Abitibi greenstone belt of Archean metavolcanic and medisedimentary units which have been steeply folded with axes trending in a general east-west orientation.
The Boomerang target is interpreted to be a dunite/peridotite unit which has undergone extensive serpentinisation.
This process is responsible for the reaction of olivine to produce magnetite and brucite, resulting in a strongly reducing environment whereby nickel is released from decomposition of olivine.
The nickel is typically partitioned into low sulphur nickel sulphide minerals.
Due to the magnetite association with mineralisation, Mr Ginn said the company had generated a 3D inversion model of magnetics to assist with targeting.