The processing plant at Radio Hill is our strategic asset - centrally located and approved for gold production, with options for other ore processing.
The centroid of the ‘hub and spoke’ model is the 0.5 Mtpa Radio Hill Processing Plant. It might be hard to believe, but this is the first time a processing plant and base, battery and precious metal resources near Karratha have been consolidated into one company. Artemis identified many different projects – gold, cobalt, copper, platinum – and we knew that to make this all work we’d need a processing plant – so we simply bought the only processing plant in the region. This significantly reduces the capital and lead time to start a mine as now have a refurbished and enhanced plant, tailings dams, key approvals and licences and electricity at our door.
The Radio Hill processing plant is 35 km via bitumen road from Karratha.
Previous operators have invested more than $60m in the plant between 1988 and 2002 (Fox Resources 2004 Annual Report). In September 2002, Fox acquired the process plant and underground mine and associated mining leases.
The 425,000 tpa flotation concentrator produced copper and nickel concentrates from the Whundo copper mine and the Radio Hill underground mine for export. In mid-2008 Fox placed the Radio Hill operations on care and maintenance due to the weakening copper price which saw copper prices fall to approximately US$3,000 by the end of 2008. In March 2017 Artemis Resources acquired the Radio Hill Operations, associated infrastructure and tenements from Fox.
In November 2017 Artemis appointed Process 26 Engineers and Constructors (“Process 26”) to refurbish the existing Radio Hill crushing and grinding circuits (announced 27 Nov 2017), to upgrade the facility by the addition of additional crushing equipment and the installation of a new gravity gold extraction circuit.
Process 26 have advanced the following:
- Crushing circuit refurbishment program - including ROM wall replaced, primary and secondary crusher refurbished, conveyor belts and screens refurbished then reinstalled.
- Mill 1 and Mill 2 - feed end trunnion bearings and heads replaced/overhauled by Hofmann Engineering. Both mill motors have been overhauled and refurbished. Metso have completed rubber lining works on both mill shells. Mill liners will be installed once plant is energised.
- All slurry pumps have been overhauled - DSM screens and cyclone cluster refurbished and installed.
- PLC and SCADA Factory Acceptance Testing (FAT) completed - onsite integration.
- Flotation thickeners, tailings sampler, flocculant plant and peripherals all onsite.
- Thickener and flocculant plant foundations and ground slabs completed.
Radio Hill plant flowsheet
Radio Hill is not just the processing plant...but we also have a nickel/copper/cobalt resource, including stockpiles of ore.
The Radio Hill nickel-cobalt-copper deposit was discovered in the early 1970s. It forms part of a small Archaean, synorogenic-synvolcanic Ni-Cu bearing mafic intrusion containing a minor ultramafic component near its basal contact. The massive and disseminated Ni-Cu-Co sulphides are hosted by thin gabbroic units underlying layered ultramafic-mafic sequence. Sulphides are confined to the feeder conduit or depressions of basal contact.
The deposit has been extensively studied and drilled by earlier companies, most notable being Fox between 2003 and 2009 when they intensely drilled and partly mined the deposit using both open cut and underground mining methods.
Artemis RC drilled the shallow mineralisation up-dip from the Fox underground workings on a regular grid in 2018. This drilling, sampling and assaying was verified by AM&A, and found to be fit for purpose, and reported in accordance with the 2012 JORC Code.
Regional geology showing Artemis structurally controlled polymetallic projects
Geology and mineralisation
Radio Hill is a small Archaean, 2892 ± 34 Ma, synorogenic-synvolcanic Ni-Cu bearing mafic intrusion containing a minor ultramafic component near its basal contact and is probably comagmatic with nearby Mount Sholl and Munni Munni intrusions. It is considered to be a Voisey's Bay, Canada analogue. The massive and disseminated Ni-Cu-Co sulphides are hosted by thin gabbroic units underlying layered ultramafic-mafic sequence. Sulphides are confined to feeder conduit or depressions of basal contact.
Mineralisation is patchy blebs of medium grained disseminated to matrix sulphides in the basal peridotite to olivine pyroxenite. Pyrrhotite, with sub-ordinate pentlandite, and chalcopyrite, forms lobate aggregates up to 12% volume of the Ultramafic host. Pyrrhotite forms layers up to 20m thick, 8m above the basal contact of an intrusion.
Post-intrusion deformation has tilted the deposit 25-40° to the southeast. The geometry has been modified by northerly trending sinistral faults.
Dolerite dykes have intruded the orebody with relaxation, following deformation, into pre-existing weakness created by faulting. Two mine-site wide dolerite dykes have truncated the orebody and act as pillars for the underground mining.
Radio Hill regional geology
Three types of mineralisation have been observed at the Radio Hill mine, which are summarised as follows:
- Massive medium to very coarse grained pyrrhotite-chalcopyrite-pentlandite ore that is often strongly brecciated and displays quartz-carbonate-chlorite veining
- Stringer/gash vein, disseminated and blebby pyrrhotite-chalcopyrite-pentlandite mineralisation associated with tremolite-actinolite-chlorite alteration and minor carbonate veining,
- Disseminated fine grained pyrrhotite-chalcopyrite-pentlandite sulphides hosted by the gabbro, and pyrrhotite dominant sulphides within the ultramafic immediately overlying the gabbro.
The gabbroic portion of the layered cumulate complex hosts the mineralisation. A generalised stratigraphic profile within the mining domain, in order of decreasing stratigraphic height, consists of ultramafic, orebody gabbro and volcanic basement.
AM&A estimated a Mineral Resource for Radio Hill nickel-cobalt-copper deposit in 2018, using the Artemis drilling only, ignoring the earlier drilling as it could not be verified as conforming to the standards required by the JORC Code (2012) for reporting mineral resources, to model the shallow resources.
The Indicated Mineral Resources were estimated within wireframes using a lower cut-off grade based on a metal factor where Cu%*0.5 + Ni% >0.5% at Radio Hill as 1.2 Mt at 0.5% Ni, 277 ppm Co and 0.7% Cu. Cobalt is a probable by-product that may be included in the Ni concentrate and so is included in the resource estimate.
|Tonnes (Mt)||Ni %||Co ppm||Cu %|
|Total within wireframe||1.2||0.5||277||0.7|
Historically there are substantial previously reported resources that are not reported in accordance with the JORC Code (2012) and therefore cannot be disclosed. For example estimates exist at depth and at F Zone to the north-west of this reported resource that need to be verified using suitable drilling that complies with the current industry standards.
Radio Hill has an existing nickel/copper sulphide Resource of 4.02 Mt @ 0.51% nickel and 0.88% copper remaining in the existing underground workings and mine development, and down plunge along the basal contact. There are also stockpiles of mined material of around 300,000 tonnes and all the processed tailings that may have reprocessing value with recent developments in technology. This stockpile and tailings material is non-JORC, but is the result of historic mineral processing of nickel and copper ores from Radio Hill since the commencement of operations back in 1986.
|Mineralisation||Classification||Tonnes||Ni %||Contained Ni (t)||Cu %||Contained Cu (t)|