Projects
Nogbele Gold Deposit
Nogbele gold deposit
Key points to the resource estimate at the Nogbele gold deposit:
- Nogbele resource estimate of 27.0Mt @ 2.1g/t for 1.80Moz gold (at 0.9g/t cut off):
- which includes M&I resource estimate of 18.4Mt @ 2.2g/t for 1.32Moz gold (at 0.9g/t cut off).
- plus additional heap leach potential material for a maiden resource estimate of 49.2Mt @ 0.6g/t for 0.93Moz gold (between the 0.4g/t and 0.9g/t gold cut offs).
- Mineralisation has so far been delineated on a 2.5 kilometre radius around the Nogbele granodiorite and remains open past the radius as well as at depth below the current resource.
- The majority of the resource has been drilled on 25m x 25m spacings and 50m x 25m spacings and is now being entirely in-filled to 25m x 25m spacings for Measured and Indicated resource categories.
Mineralisation at Nogbele consists of multiple parallel and sub-parallel zones of broad hematite and/or magnetite, silica and pyritic alteration, sericite schist’s and lode quartz veins that dip between ‘flat’ and 60 degrees to the north, ‘wrapping’ around the ‘nose’ of the Nogbele granodiorite into the surrounding sediments and mafic units.
Mineralisation is associated with major extensional zones around the northern margin of the Nogbele granitoid intrusive in a similar geological setting to Randgold’s 4.2Moz Tongon Gold Deposit located approximately 30 kilometres to the south of the Banfora Gold Project.
The DFS proposes the 3.5Mtpa gold mill and process plant to be located in the vicinity of the Nogbele deposit.
Refer to map and cross sections in Appendix 3 of ASX release 09/07/2012.
Potential heap leach material at the Nogbele gold deposit
Key points to the resource estimate for potential heap leach material at the Nogbele gold deposit:
- A maiden resource estimate for potential heap leach material at the Nogbele gold deposit of
49.2Mt @ 0.6g/t for 0.93Moz gold (between the 0.4g/t and 0.9g/t gold cut offs). - Reported potential heap leach material is derived from all areas of the modelled Nogbele resource with some additional low grade domains to the reported 0.9 g/t lower cut resource (27.0Mt @ 2.1g/t for 1.80Moz)
- Preliminary metallurgical results from column test work on oxide indicate high potential for successful heap leach recovery (refer ASX release 15/5/12).
- Metallurgical test work on the transitional and primary material is currently underway
Preliminary results of +90% average gold recoveries from recent column leach test work on bulk trench samples across three portions of the Nogbele gold deposit targeting lower gold grade ‘halo mineralisation’ indicate a real potential for successful heap leach gold recovery.
The samples taken from the Nogbele area are representative of both Nogbele granitoid, mafic and sediment oxide with head assay grades in the vicinity of 0.6 g/t gold.
The heap leach amenability test work was carried out by ALS AMMTEC laboratories under the supervision of Paul Elms Metallurgical Services Ltd.
The column test work results are extremely encouraging with column cyanidation leach testwork showing excellent extractions with average recoveries of 93% after only 45 days in the columns.
World heap leach experts Kappes, Cassiday & Associates Australia Pty Ltd have been engaged by the Company to undertake a detailed assessment of the heap leachable lower grade gold at the Nogbele gold deposit in addition to the 3.5Mtpa CIL operation in the DFS.
Results of the heap leach studies are expected at the end of 2012, separate to the current DFS.