Key points include:
- Scope to significantly improve sales revenue from Bunyu graphite products – initial testwork shows significant increase in the percentage of high priced (+30# and +50#) graphite flake and a reduction mainly in the lower priced fine graphite flake.
- Other key results from the first phase of the testwork program include:
- Production of a 99.95% thermally purified graphite product suitable for a number of end uses including battery anode material feedstock.
- ICP analysis which identified very low boron levels in the thermally purified graphite which makes the Bunyu product suitable for nuclear industry components and as a feedstock in the manufacture of synthetic diamonds.
- Excellent preliminary BET surface area, Scott volume and tap density measurements which point to the Bunyu graphite product being a good quality feedstock for Li-ion battery cell anode material.
- Volt continues to advance its Mauritian Note Offer to raise up to US$30M and alternative finance sources to fund Stage 1 development of Bunyu Graphite Project.
Tanzanian-focused flake graphite developer Volt Resources Limited (ASX: VRC) (“Volt” or “the Company”) is pleased to provide the excellent results from the first stage of a testwork program on graphite ore from the Bunyu Graphite Project in Tanzania. The testwork program was undertaken by highly respected technical group, American Energy Technologies Co. (“AETC”) which is headquartered and operates research and laboratory facilities in Chicago, Illinois.
AETC testwork program summary
In January 2020, Volt commissioned AETC to undertake a testwork program using a representative sample from drilling completed as part of the Stage 1 Feasibility Study 1 at the Company’s Bunyu Graphite Project. A graphite product from the Bunyu ore sample was prepared and analysed for certain physical, chemical and processing properties to provide information for its suitability for several value-added graphite market applications including as anode feedstock for Li-ion battery cells.
The representative sample of ore was obtained from a composite sample produced from a metallurgical drilling program undertaken as part of the Stage 1 Feasibility Study (FS). Further information regarding the drilling program and composite sample are included below.
Volt’s Bunyu Graphite Stage 1 Project will produce on average 23,700tpa of natural flake graphite product at up to 96% TGC. Product size, grade distribution and average sales price reported in the Stage 1 Feasibility Study are shown in the following table.
Comminution Testwork
The samples supplied were screened to -3.35mm and this was confirmed with a light top -size crush at the US Laboratory prior to grinding. Wet grinding was undertaken in a ball mill in 4.5lbs batches for 5 minutes at 70% solids. Polishing mill utilised 0.5” diameter alumina balls at 20 minutes for 50 wt. % solids as the operating conditions.
Flotation Testwork
A Westpro Machinery Inc. (Vernon, BC, Canada) continuous mineral beneficiation system by froth flotation was employed to separate graphite from the bulk of the host rock. The model FL3, having a 3 ft3 capacity per cell, constructed in a four-cell arrangement was used. The flotation cell has a range of operating controls and common operating parameters to other testwork programs. Also, a smaller 3 Litre cell was used for preliminary testing of froth formation (shown below)
Froth Flotation Cell Testwork
In the testwork conducted, concentrate grade recovery and flake preservation had an emphasis on the use of a heavy molecular oil method (AETC’s frother is referred to as AMO). This method offers an alternative to the industry standard reagent, kerosene. The success of this method is based on a synergistic use of high shear mixing and AMO.
By the end of the primary beneficiation process, aa 86.6 wt. % TGC concentrate was produced with recovery of at least 68.5 wt. % of graphite available for beneficiation. This is an effective method to produce flake graphite concentration for the purpose of subsequent down-stream processing and characterisation for a range of applications.
Producers that use the industry standard method, which includes kerosene as an additive and utilizes large paddles as an agitator of material, typically require at least a few more polishing grinds, the application of an attrition mill, and a greater number of cleaner circuits to achieve a similar result, and this would be more complex in a laboratory application where the focus was to produce flake graphite cost effectively for subsequent downstream processing testwork.
The testwork undertaken included both physical and chemical characterisation, and Industry standard analytical techniques have been employed.
The recovery of 68.5 wt.% of the total available concentrate was deemed appropriate by the consulting laboratory, extracting what they believe was as a fully representative sample of flake graphite product sample for thermal purification by the induction furnace into the secondary processed grade.
Below is a table with the Stage 1 product size distribution compared with the product distribution from the AETC graphite product from the aforementioned testwork program.
There is a substantial increase in the percentage of high priced +30# and +50# graphite flake with a consequent reduction mainly in the lower priced fine graphite flake. With further testwork and analysis, this could have major economic benefits for both the Stage 1 and Stage 2 Bunyu project.
If through further testwork the benefits in flake size distribution continue, the next step would be to consider the incorporation into the Stage 1 feasibility study and flowsheet design. The operating and capital cost changes to the current Stage 1 plant are expected to be minimal and more than offset by the substantial increase in sales revenue.
The above results are from the first phase of the AETC program and the Company looks forward to releasing further results as they become available.
Scanning electron microscope image of +30# graphite flake from Bunyu screened product
FS Metallurgical Drilling Program
As part of the 2017/18 Stage 1 FS program of work, an infill drilling program was undertaken at Bunyu 1 to increase the geological understanding of the ore body and the level of resource confidence and, using this additional information, to refine the planned mining schedule and the Stage 1 pits.
As part of this scope of work diamond drill holes were drilled in areas of known mineralisation to map out additional geological, geotechnical and metallurgical information.
The diamond drill hole collar details and hole depths that contributed to the metallurgical composite sample are detailed in the following table.
2018 FS Drill Core Composite Details
Cut ½ and ¼ drill core samples were delivered to ALS Metallurgy, at their Balcatta facility during January 2018. The drill core was crushed to -3.35mm and the following composites were formed, which were homogenised and the head assays determined.
From the Master Composite a 67kg of sample was made available for this program of testwork and dispatched from ALS Metallurgy in December 2019.
Management commentary
Volt’s Chief Executive Officer, Trevor Matthews, commented;
“We are delighted with these initial testwork results provided by AETC which is further confirmation to the previous testwork programs during the PFS and FS stages of project study & development that Bunyu’s flake distribution is suitable for supply to traditional markets and for use in new high demand applications such as battery anode end use markets.
“Given these results there is an opportunity to make improvements to the project economics outlined in the Stage 1 Feasibility Study for Bunyu, with further details on these changes to be provided in due course.
Our Stage 1 funding initiatives continue to advance, even in light of the current COVID-19 pandemic which is causing delays in the process, and I look forward to providing updates on our Mauritian Note Offer and other funding sources in due course.”
Authorised by:
Trevor Matthews
Chief Executive Officer
FOR PERSONAL USE ONLY
For further information please contact:
Trevor Matthews – Chief Executive Officer
Tel: +61 8 9486 7788