Mining
Manganese Exploration and Mining
A total of 346 drill holes and 31 costean have been completed to date.
Winchelsea Mining Pty Ltd (Winchelsea) holds exploration tenure on Winchelsea, Bickerton and Sea Country including Connexion Island as well as tenure on Blue Mud Bay, Sandy, Edward and Marie Islands.
On Winchelsea Island, Exploration Licence (EL27521) was granted on 21 December 2018 for a period of six years to explore for manganese. The exploration license covers 20.39 km2 with the remainder of the island being under another Winchelsea Exploration License application EL32022 (26.89km2).
There had been no previous documented mineral exploration on Winchelsea Island prior to the granting of EL27521 in late 2018.
Currently, there has been five phases of exploration drilling and costean sampling conducted from September 2019. A total of 450 drill holes and 101 costean have been completed to date. A maiden JORC (Joint Ore Reserve Committee) Report was completed on Phase 1 and 2 drilling result by Xenith Mine Consultants.
Phase I and Phase II reverse circulation (RC) drill programs were completed with a total of 282 holes drilled for 3865.5m. The excavation of the costean provides us with the ability to channel sample, visual confirmation of ore body and bulk sample for the processing plant design.
A further 350 exploration (aircore) drilling and 70 costean sampling in Phase IV and V Advanced Exploration Program was completed in August 2020 …
A further 350 exploration (aircore) drilling and 70 costean sampling in Phase IV and V Advanced Exploration Program and will provide results which will be utilized to update the JORC Report to a Measured Status with a target published date of September 2020.
The exploration program has delineated a significant discovery of a shallow modelled Mn mineralised deposit approximately 1km (NS) by 2km (EW) area in the central southern region of the tenement that displays significant geological and grade continuity. There are additional areas to to north of the main deposit.
The deposit is similar in style to the orebodies currently and successfully mined on Groote Eylandt with the mineralisation in this region showing no or very little overburden with the Mn mineralised intervals outcropping to the surface which results in a very low strip ratio.
Recent results from the Phase III tests pits have shown a large increase in the sample yield results compared to the RC drilling samples. The upgrade in yield varies from approximately 20 to 50% (absolute) with many samples in the order of 25 to 35% improved. Further validation I sbeing conducted but the results are illustrating (~70%) yield washed over a 0.6mm screen compared to the 35% yield with the RC samples.
This would translate to an increased washed tonnage figure of ~10Mt.
Our People
It is planned that all mining and processing will take place on Winchelsea Island within the accommodation, stores, administration and lay down areas planned to be located at Little Paradise Bay as the project’s Logistics Hub, the closest point of contact with the larger Groote Eylandt.
The project is an owner operation with all technical and operating staff including Marine Services staff employed by Winchelsea Mining. There will be local employment opportunities for operations, contractor support and construction for 50% local indigenous personnel. This targeted residential operation will have minimal FIFO specialists with clan-based enterprises contracted for specialised support such as barging services, bio-security, mechanical services, environmental monitoring and accommodation services.
The island is approximately 50km off the eastern coast of Arnhem Land, approximately 650km east southeast of Darwin and approximately 1,000km west northwest of Cairns.
Akwamburrkba falls within the Anindilyakwa Land Council (ALC) area with access to the island is by boat from Groote Eylandt which is Australia’s third largest island with an area of 2,285km2. Under the Aboriginal Land Rights Act (NT) 1976, the Traditional Owners hold inalienable freehold title over the island.
There will be local employment opportunities for operations, contractor support and construction for 50% local indigenous personnel.
Exploration License (EL27521) was granted on Winchelsea Island on December 21st, 2018, for a period of six years to explore for manganese. The exploration license covers an area of 20.39 km2, with the remaining land on the island being covered by another Winchelsea Exploration License application EL32022 (26.89km2). On March 23rd, 2022, a mining lease, ML 32704, was granted for a 30-year period, covering 14.40 km2. Prior to the granting of EL27521 in late 2018, no documented mineral exploration had taken place on Winchelsea Island.
Since September 2019, six phases of exploration drilling and costean sampling have been conducted on the island. Phase 1, phase 2 and phase 3 exploration programs have consisted of 446 reverse circulation (RC) holes (5,600m of drilling) and 31 costeans. Phase 4, 5 and 6 exploration programs have consisted of 353 aircore (ac) holes (3,500m of drilling) and 130 costeans. Phase 6 exploration has also included 12 bulk samples to be used for a metallurgical testing program that has been undertaken in laboratories in Perth, Western Australia. In total, approximately 800 drill holes, 161 costeans, and 15 bulk samples have been completed on Winchelsea Island.
A LiDAR survey was conducted over the exploration lease during 2021, which provided superior topographic control over the area. With current metallurgical test work, conducted on the twelve bulk samples (average of 560kg weight) taken from select locations within the Winchelsea project, demonstrates that a manganese product through a process of primary crushing followed by scrubbing and secondary crushing generates a lump (-75 +6mm) and fines (-6 +1mm). Product is modelled to achieve a predicted Manganese grade for Lump (-75 +6mm) at a weight average at >40%. Some lump mineralisation has ability to achieve >45.0%. Fines (-6 +1mm) product is predicted to achieve a weight average >32% across all mineralised ore sources. Some fines mineralisation has ability to achieve >40.0%. A high Manganese recovery is generally achieved for the +6.3mm size fractions with the overall average recovery of 72%.
The exploration program has delineated a significant discovery of a shallow modelled Mn mineralised deposit approximately 1km (NS) by 2km (EW) area in the central southern region of the tenement that displays significant geological and grade continuity. There are additional areas to the north of the main deposit. The deposit is similar in style to the orebodies currently and successfully mined on Groote Eylandt, with the mineralisation in this region showing no or very little overburden with the Mn mineralised intervals outcropping to the surface, resulting in a very low strip ratio.