Indonesia
Manganese Project
Substantial deposits of high-grade manganese mineralisation have been discovered in two locations in the Lakuwahi Caldera; Manganese Valley (Mn Valley) and Batu Hitam West (BHW) (Figure below). The deposits are near surface and partially cap gold-silver oxide and/or polymetallic mineralisation is situated on the eastern flank of the Batu Hitam polymetallic deposit and the smaller deposit at Batu Hitam West overlies gold-silver-lead-zinc-copper mineralisation.
The high-grade manganese mineral resource is outlined below:
| Deposit | Material (t) | Mn Grade (%) | Mn Metal (t) |
|---|---|---|---|
| BHW | 37, 000 | 46.5 | 17, 000 |
| Mn Valley | 529, 000 | 41.8 | 221, 000 |
| Total Inferred | 566, 000 | 42.5 | 238, 000 |
(source: Robust Resource Limited, Lakuwahi Project, Manganese Resource Estimate, Mining Associates, 4 November 2013)
In their report, Mining Associates, under requirements of the JORC code, have made certain assumptions that show that the Lakuwahi manganese resource has "Reasonable prospects of economic extraction". The assumptions used are shown in the table below.
| Parameter | Unit | Value |
|---|---|---|
| Capital cost | US$/t ore | $ 8.67 |
| General and admin cost | US$/t ore | $ 3.00 |
| Processing cost | US$/t ore | $ 3.00 |
| Average mining cost | US$/t ore | $ 5.20 |
| Total cost | US$/t ore | $ 19.87 |
| Manganese price | US$/t ore | $ 220 |
| Average recovery- Mn | 95% | |
| CUT-OFF GRADE Manganese (Mn), % | 10% | |
(source: Robust Resource Limited, Lakuwahi Project, Manganese Resource Estimate, Mining Associates, 4 November 2013)
These figures are approximate due to the early stage of this project, and the costs are assumed costs. Robust is undertaking a scoping study into development options for the high-grade manganese deposits, at which time the above costs will be validated. Initial studies indicate a viable direct-shipping-ore (DSO) operation may be established, once an export licence is obtained from the Indonesian authorities.
Robust will undertake a feasibility study (FS) for the manganese project, which is scheduled for completion in the September quarter of 2014. This study will include additional drilling and assays to bring the mineral resource to JORC Measured and/or Indicated categories, studies on mine planning, beneficiation (if required), marketing and an estimate of project capital expenditure and operating expenditure.
The timing of the manganese FS will coincide with finalisation of the Company's efforts to obtain a mining operating licence from the Indonesian Government.
Subsequent to the completion of the resource estimate, assay results have been received from diamond drill hole LWD 372 located at Batu Hitam South, approximately 130 metres to the south of the current Manganese Valley mineral resource (Figure above).
LWD 372 intersected near-surface, high-grade manganese mineralisation (Table 1) which indicates that extensions to the current manganese resources are highly likely.
| Hole Number | Easting WGS84 Zone 52 |
Northing WGS84 Zone 52 |
RL m |
Azimuth grid |
Inclination | From (m) |
To (m) | Interval (m) | Mn (%) |
|---|---|---|---|---|---|---|---|---|---|
| LWD372 | 319,294.0 | 9,156,869.8 | 286.7 | 180 | -60 incl. |
10.8 | 17.0 | 6.2 | 45.13 |
| 13.3 | 15.8 | 2.5 | 54.19 |
Table 1: Drillhole collar details and summary of high-grade manganese intersections.
To view the most recent Manganese Scoping Study, please click here.