Molyhil is located 220 kilometres north-east of Alice Springs (320km by road) within the prospective polymetallic province of the Proterozoic Eastern Arunta Block in the Northern Territory.
Summary of Molyhil Mineral Resource Estimate (Reported on 30 January 2014)
Mineral Resource reported at 0.1% combined Mo + WO3 Cut-off and above 200mRL only. Minor rounding errors may occur in compiled totals.
Thor Mining PLC holds 100% equity interest in this reserve. The Company confirms that it is not aware of any new information or data that materially affects the information included in the market announcement dated January 2015 and that all material assumptions and technical parameters underpinning those estimates continue to apply and have not materially changed.
The statement of reserves is derived from the Indicated portion of the resource estimate only, and the Inferred portion is excluded from the calculations. The long-term prices used were US$300/mtu for WO3 concentrate and US$7.92/lb for Mo concentrate at an exchange rate of US$0.75 to A$1.00. The WO3 and Mo Processing Recovery post ore sorting used was 85% and 77.8% respectively.
The Pilot Mountain tungsten project is situated 200km southeast of Reno in Nevada USA.
The Desert Scheelite Indicated and Inferred Resource comprises 9.9 million tonnes @ 0.26% WO3, 0.14% Copper, and 19.4g/t (grams/tonne) Silver.
The Garnet Inferred Resource estimate comprises 1.83 million tonnes @ 0.36% WO3.
Both resource estimates were announced on 22 May 2017.
In addition to the 2014 Desert Scheelite resource, the Pilot Mountain project has significant exploration potential comprising Exploration Targets* totalling 11.0 – 22.6 Million Tonnes at 0.3 to 0.5% WO3 summarised in table 2.
* Exploration Targets are conceptual in nature and there has been insufficient exploration to define a Mineral Resource under the 2012 JORC Code. It is uncertain if further exploration will result in the determination of a Mineral Resource.
The potential of the multiple Pilot Mountain exploration prospects is provided as Exploration Target values summarised in table 3. Prospects have been classified as either Tier 1 or 2 reflecting the level of confidence in the prospect.
In January 2015 Thor announced an updated feasibility study for Molyhil with robust outcomes.
In 2013, Thor received a Letter of Intent (LOI) from Global Tungsten and Powders, of Pennsylvania USA, undertaking to purchase 70% to 75% of tungsten concentrates produced from Molyhil over the life of the mine.
The Definitive Feasibility Study (DFS) included results from substantial metallurgical testwork by independent consultants, and the resultant process flow sheet was incorporated into the technical and economic assessment. The testwork demonstrated the production of a Primary Tungsten Concentrate assaying 72.9% WO₃, with a recovery of 67%, and a Primary Molybdenum Concentrate assaying 51.4% Mo, with a recovery of 77.8%.Subsequently the Company has identified the opportunity to enhance the recovery of tungsten via a further process step comprising flotation and electromagnetic separation of tailings. The outcome from this has been validated by independent testwork and demonstrated to improve tungsten recovery to 85%.
Thor has completed the Public Environmental Report for the Molyhil Tungsten and Molybdenum Project. This report has been accepted by the Department of Regional Development, Primary Industry, Fisheries and Resources in the Northern Territory
This report was approved on the 15th July 2007 by the DRDPIFR (NT), who also confirmed in December 2011 that the approval remains current. The report is available on request.
THOR Mining PLC has also obtained all the required agreements between the Traditional Owners of the land, and THOR Mining PLC, to enable the Molyhil Operations to proceed with the recognition and support of the Traditional Owners.
The Tripartite Deed records the terms of the Agreement between the parties in accordance with the Native Title Act and is between the Arrapere People, the Central Land Council and Thor Mining PLC.
The feasibility study mining plan largely reflects the open cut ore reserve statement, and therefore the life of the proposed operation in the Definitive Feasibility Study (DFS) is of the order of 4 years. Pit optimisation studies, however, reveal that a relatively modest 7% improvement in economic factors have the potential to increase the reserve and mining life by over 50%. By contrast, a 20% deterioration in economic factors shows a much more modest 13% reduction in mining life and reserve.
The potential beyond that estimated life may include:
Extending the open cut operation and/or underground mining to extract some of the 65% of the resource, laterally and at depth, which is not included in the ore reserve.
Potential production exploration targets including some recently identified within several kilometres of Molyhil.
Upon completion of the updated DFS, Thor is planning to secure off-take agreements for the balance of tungsten and molybdenum concentrates, and finance to support the development of mining and processing operations at Molyhil. It is anticipated that the first production of concentrates will commence during 2018.
Close spaced historic drilling was undertaken by Union Carbide Corporation in the 1970s covering an area of 70 hectares in the vicinity of the abandoned historic Garnet mine. Many of the holes are short, only penetrating only the upper one or two of the shallow dipping tungsten mineralised horizons. Seven holes across the area define a total tungsten mineralised thickness of 10 to 13 metres comprising three separate horizons within a 30 to 40 metre sequence of calcareous meta-sediment host rock.
The Garnet Exploration Target value; 2-3 million tonnes @ 0.3 - 0.4% WO3 is derived from the mineralised thickness, the target area, an estimated bulk density of 2.8 and a conservative factor of 0.1 to allow for the improbability of the whole of a target area being mineralised.
The 1981 Kaiser Engineering resource estimate for the Gunmetal South comprises 2-3 million tonnes at 0.3 to 0.5% WO3. The estimate was based on 80 to 150 metre spaced grid of drilling undertaken by Union Carbide Corporation (Figure 4). This resource estimate does not comply with current resource reporting standards and is thus presented as an Exploration Target.
The Exploration Target tonnage correlates with the geometric estimate based on area (500x250m), 7 metre total thickness and an average bulk density of 2.8 tonnes per cubic metre.
The Desert Scheelite resource detailed in the Golder report 2012 is not included as an exploration target. The deposit remains open to E, W & at depth along its whole strike length. Extensions to mineralisation in each of these three directions are treated as individual targets and described separately below.
The most easterly hole into DS mineralisation (DSDD 15) intersected exceptionally strong mineralisation of 13.9m averaging 0.89% WO3, 1.75% Cu at 180m below ground level and 130 metres below base of unmineralised cover. There are currently no apparent reasons why this mineralisation should not continue.
An exploration target of 2 – 3 million tonnes at 0.3 to 0.5% WO3 has been proposed based on an easterly extension equivalent to one third of the existing Desert Scheelite resource. Thor Mining holds tenements over the immediate potential extensions of this mineralisation.
Historic Good Hope drill hole (RDH2) intersected 36m @ 0.41% WO3 from 3 metres depth indicating significant potential. Surface outcrop and historic small scale mine workings indicate Good Hope mineralisation may comprise multiple sub vertical lodes which are yet to be effectively drill tested.
The geological setting is similar to Desert Scheelite including; outcropping skarn and quartz monzonite within marble host rock. Strong potential exists for economic quantities of tungsten mineralisation to occur at Good Hope. The Good Hope Exploration Target of 0.5 – 1.5 million tonnes at 0.4 – 0.5% WO3 is based on one sixth of the Desert Scheelite resource.
Gunmetal Historic (green zone Figure 4) zone surrounds the historic mining area. Geological mapping indicates extensive skarn and quartz monzonite outcropping within marble. Historic mining records and drill intersections in this area indicate robust tungsten mineralisation. Historic drill hole GM11 intersected the following four zones;
An Exploration Target of 0.5 - 1.0 million tonnes at 0.4 – 0.5% WO3 is proposed. Historic drill data and the potential of near surface and opencut mining make this a Tier 1 target.
Greasewood Spring lies to the east of the Gunmetal mine and has comparable geology. Kilometre spaced historic drilling intersected tungsten at depth confirming the prospectivity of this area.
The prospective geology including hornfels and skarn in addition to the alluvial cover in the order of 60% give this target area a reasonable level of prospectivity. The ET value is derived from Gunmetal Historic scaled up to allow for the larger area of Greaswood Spring.
The Good Hope Zone is an area entirely under volcanic and alluvial cover extending from mineralisation at Desert Scheelite in the south the mineralisation at Good Hope prospect in the north.
The zone comprises 247 hectares and has had no exploration since three kilometre spaced holes drilled in the 1970’s
The ET for this area is set at 1 – 2 million tonnes at 0.2 – 0.3% WO3.
The Desert Scheelite Depth Extension is a relatively low risk target located down dip of the currently deepest drilling at less than 100 metres. By nature of its depth the target will be high cost to drill and unlikely to be drilled before commencement of mining of the current Desert Scheelite resource.
The ET is based on one sixth of the current DS resource.
The remaining Tier 2 Exploration Targets all have target values of less than 1 million tonnes. They are considered prospective as a result of their geology and proximity to known mineralisation.
First phase testwork has been undertaken by Guanzhou Research Institute of Non Ferrous Metals on a sample of Pilot Mountain ore. The results of the testwork have shown that the ore can be treated by flotation or by flotation and WHIMS to produce a saleable concentrate. Further testwork is required to determine optimum recovery and to establish a process flowsheet.