Tanzania – African focused, ASX-listed junior explorer Walkabout Resources has received excellent test results from initial metallurgical test work conducted over four test regimes on core samples from the high grade ore zone at the Lindi Jumbo graphite project.
The preliminary flotation tests were planned with the intent to maintain the graphite flakes as coarse as possible, while achieving high recovery to concentrate.
- Initial testwork confirms excellent metallurgical results from The Gilbert Arc
- Graphite recovery of >98%
- Concentrate grade of 95.7% Total Graphitic Carbon (TGC) achieved
- A standardised and simple roughing flotation regime achieved excellent recovery with a coarse primary grind (P100 at 850μm)
- Excellent flake size retention with up to 57% Large and Jumbo flakes retained at concentrate grade of 94.3%
- Large flake graphite is of higher purity and better grades
- No significant deleterious elements identified
- Further work to optimise results ongoing
Flotation test work was conducted by Nagrom Metallurgical under the consulting management of Perth based metallurgical specialist consultants, Battery Limits.
Walkabout Resources MD Allan Mulligan is excited to achieve these results at such an early stage of the test work regime.
“Very few projects have been able to fast track to a stable test regime so efficiently. These tests prove that Lindi Jumbo graphite can be recovered and that the high ratios of Jumbo flake are present.
“Graphite beneficiation is first about recovery and concentrate grade and then about flake size preservation. This will provide a strong base for optimising the quality of graphite product into concentrate and meet our objective of producing a niche, high grade, premium product,” he says.
Testwork and results
A fresh ore high grade sample composite has been compiled from recent diamond drill program for preliminary metallurgical testwork.
The ore composite was generated to assess the ore’s amenability to beneficiation by froth flotation and also to identify the nature, flake size and occurrence of the graphite in a selection of drill core samples, and flotation products.
The testwork composite comprised sample intervals from drill holes LJDD001, LJDD002 and LJDD003.
These holes are located within the high grade zone of the Gilbert Arc antiformal structure at the project. In addition a bulk sample of outcrop within the oxide zone has been received for testing.
Head assay value for the ore composite sample was 21.0% TGC. All assays are reported using the differential Loss on Ignition (LOI) method.
The preliminary flotation tests were planned with the intent to maintain the graphite flakes as coarse as possible, while achieving high recovery to concentrate. The flotation test regime performed to date was designed to establish standardise rougher flotation conditions and determine preliminary concentrate cleaning characteristics.
For rougher flotation, ore was stage ground and wet screened at each target screen size, with each stage of rougher tailings re-ground and re-floated in a subsequent rougher flotation stage.
Results found that multi stage rougher and scavenger flotation resulted in excellent recovery >98%, while single stage grind rougher flotation maintained good overall recovery of 96% with only a modest increase in recovery achieved at finer grind sizes.
Further, a standardised roughing flotation regime achieved good recovery at a coarse primary grind (P100 at 850μm), typically producing > 94% graphite recovery with a mass recovery of 32%-35%.
The test procedure for cleaning involved rougher flotation using the conditions developed, followed by multiple cleaner flotation stages. The concentrate was subjected to a polishing grind to increase graphite particle liberation prior to each cleaner step.
Cleaner flotation test work was focused on achieving graphite concentrates grading >94% TGCusing typically 3-4 stages of cleaning and regrind and achived excellent graphite recovery, which was maintained at >95%. Concentrate grade >95% TGC were also achieved at relatively coarse graphite particle size distribution.
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