Cobalt Blue Holdings Ltd (ASX:COB, OTC:CBBHF) has improved confidence in the economic feasibility of the Broken Hill Cobalt Project (BHCP) in Far West New South Wales by way of an updated mineral resource estimate (MRE).
The update has increased overall resources by 32% to 126.5 million tonnes at 867 ppm cobalt-equivalent - 690 ppm cobalt, 7.5% sulphur and 134 ppm nickel for 87,300 tonnes of contained cobalt, 9.51 million tonnes of sulphur and 17,000 tonnes of nickel at a 275ppm cobalt equivalent cut-off.
Stepping-stone in DFS
Importantly for the company’s definitive feasibility study (DFS) as well as mine planning and scheduling, measured and indicated resources now comprise 66% of the total MRE. The estimate is a major stepping-stone in the completion of the DFS.
The mineral resource estimates for the BHCP deposits (at a 275 ppm CoEq cut-off) detailed by mineral resource classification.
Much of this improvement is from the Big Hill deposit at which infill drilling has supported an improved resource classification with 31% of tonnes classified as measured and a further 54% classified as indicated.
This is particularly important given strategic mine scheduling considers production from Pyrite Hill and Big Hill during the first 10 years of operation.
Resource upgrade
Cobalt Blue CEO Joe Kaderavek said, “The recent drilling program has further advanced our assessment of key modifying factors critical to the definitive feasibility study.
"The realisation of an improved resource classification for Big Hill is particularly positive with 66% of the mineral resource now available for potential conversion to proven and/or probable ore reserves.
"The mineral resource will form the basis of detailed life of mine planning and scheduling.”
BHCP location and tenement holding.
Changes from 2021 MRE
Changes from the previous MRE compiled in 2021 can be attributed to the refinement of mineralisation and waste domains as well as cut-off revision and conceptual pit limit optimisations.
The mineralisation and waste domains were updated using the additional drilling completed during 2022–2023.
At Big Hill, increased drilling density enhanced geological constraint and supported an improved classification with 85% of the resource classified as measured and indicated, compared with the former estimate which comprised just 60% indicated and 40% inferred.
Resource extension areas
Separately, three areas of resource extension contributed to organic resource growth including:
- Area A – a zone of outcropping pyritic quartz-albite gneiss about 150 metres southeast of the main body of the Railway deposit where drilling intersected zones of steeply dipping mineralisation, over around 300 metres of strike and ranging between 15 and 20 metres in thickness within the broader quartz-albite gneiss host.
- Area B – comprising the north-eastern strike extension of the Big Hill South deposit, where drilling improved definition of mineralisation over around 100 metres of strike and ranging between 15 and 20 metres in thickness.
- Area C – comprising the north-eastern strike extension of the Big Hill North deposit, where drilling defined mineralisation over around 50 metres of strike and ranging between 15 and 20 metres in thickness.
Also, key inputs used in the calculation of the cobalt equivalency cut-off grade have been updated considering modifying factors derived from the continuing DFS.
Similarly, assumptions used for the completion of conceptual pit limit optimisations to constrain reporting of the MRE have been updated considering modifying factors derived from the continuing DFS.