Overview
Status | Temporary Suspension |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Filter press plant
- Crush & Screen plant
- Dry Screening
- Dewatering
- Flotation
- Magnetic separation
|
Mine Life | 3 years (as of Jan 1, 2019) |
All planned mining and processing activities, including further exploration and geology work at Bukit Besi mine, were completed on track for FY2021. |
Source:
p. 444
Fortress’s wholly owned Bukit Besi Iron Project comprises two granted Mining Leases covering a combined area of 5.2 km2.
Summary:
The iron ore deposits consist principally of magnetite and its alteration product martite. There is some primary haematite and large amounts of secondary haematite. Goethite is also present.
Almost all the orebodies occur as replacements in the sediments along or within a hundred metres of their contact with the granite. Magnetite and haematite replacement can also be seen within the granite. Here, fragments of altered sedimentary rock in this ore suggest that the ore has completely replaced bodies of shale engulfed by the granite. Where overburden remains in-situ, boulders of magnetite, haematite, and goethite float can be found.
Although five mineralisation styles (replacements in limestone skarns, replacements in shale, lenses and pod-shaped bodies, dissemination and replacements in granite), most of the remaining identified mineralisation at the Project, as well as the bulk of the ore produced historically is associated with the shale units in two deposit types:
1. Irregular masses have formed where there was no bedding left to act as a control. The ore generally consists of magnetite, martite, and secondary haematite with colloform banding, while the gangue is simply unreplaced shale.
2. Regular tabular bodies where the bedding was not destroyed during the period of metamorphism. These replacements vary in thickness from simple partings parallel to the bedding planes up to units 10 m in thickness. The lengths of these bodies are also variable; some more than 30 m long have been identified. In the western part of the historical main mining area the shale is host to numerous closely spaced tabular orebodies containing considerable quantities of pyrite. In many instances the replacements are part tabular and part highly irregular in outline. Pyrite is generally more abundant in the tabular replacements than in the irregular type. It is thought possible that the bedding planes acted as channels for this mineralisation, and where these had been destroyed its ability to penetrate the shale was considerably reduced.
Only one generation of magnetite has been recognised in the Project area. While this replaces skarns and other rocks, it is replaced itself by later sulphides where it has been corroded and altered to martite along grain boundaries and fractures. Replacement bodies of bother primary and secondary haematite are found across the Project area. Hill (2011) notes that significant orebodies at the Project have all been found within 100 m of the contact of the granite. The mineralising fluids made their way along bedding and contacts in the country rocks, as well as fracturing caused by the intrusion itself. The formation of embayment structures in the granite shale contact allowed for localised replacement. Here, the intruded sediments were partially but not altogether isolated, producing structural traps.
Summary:
The operation utilises a conventional truck and shovel open pit mining method. Material is being mined on a bench height of 2.0 m, with drill and blast limited to a one bench depth in areas containing mill feed material. The average strip ratio is 4 to 1 waste to mill feed.
The current operations consist of two open pit mining areas which are located within mining lease ML7/2013, with conventional excavator and trucking of feed to a magnetite processing plant which is located within mining lease ML4/2013.
Processing
- Filter press plant
- Crush & Screen plant
- Dry Screening
- Dewatering
- Flotation
- Magnetic separation
Flow Sheet:
Summary:
The processing flowsheet uses a 10-stage circuit which is summarised as follows:
1. Near-pit jaw crushing and coarse cobbling of the ore using dry magnetic separation.
2. Dual ball milling to produce a product P40 75 m that is pumped for screening.
3. Screening using a 1 mm aperture screens, with undersize passing to a Stage 1 magnetic separation and the oversize recycling to the ball mills.
4. Stage 1 magnetic separation, at a nominal 2,400 Gauss, to remove barren material to tailings and a magnetic fraction for regrind.
5. A regrind circuit, to grind the coarse magnetic material.
6. A cyclone cluster to direct fines material (P80 75 m) to flotation and the coarse material for further regrinding.
7 Stage 2 magnetic separation, at a nominal 2,400 Gauss, of the cyclone overflow material to remove a barren tailings stream.
8. Reverse flotation of the Stage 2 magnetic material where the sulphur-rich f ........

Production:
Commodity | Units | 2021 | 2020 | 2019 |
Iron Ore
|
kt
| ......  | ......  | ......  |
All production numbers are expressed as concentrate.
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Operational Metrics:
Metrics | 2018 |
Annual production capacity
| 480,000 wmt of iron ore concentrate |
Reserves at February 28, 2021:
Based on a block cut-off grade of 10% Fe and magnetic susceptibility greater than 100 and sulphur less than 10%.
Category | Tonnage | Commodity | Grade |
Indicated
|
0.28 Mt
|
Iron
|
42.57 %
|
Inferred
|
5.49 Mt
|
Iron
|
46.07 %
|
Total Resource
|
5.78 Mt
|
Iron
|
45.9 %
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
.......................
|
|
Mar 19, 2019
|
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Aerial view:
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