Summary:
The Lofdal property is underlain by Paleoproterozoic metamorphic rocks of the Huab Metamorphic Complex, which outcrop as an inlier of the Congo Craton surrounded by stratified rocks of the Damaran Orogen. The metamorphic basement was intruded at ca 750 Ma by alkaline
silicate rocks and carbonatites of the Lofdal carbonatite complex. The complex comprises an early silicate intrusive assemblage of dominantly nepheline syenite, and a later carbonatite intrusive assemblage ranging from sovite through dolomitic and ankeritic carbonatite.
The entire complex, as it is presently understood, comprises a central intrusive core characterised by a number of plugs of nepheline syenite and carbonatite with associated diatreme breccias, surrounded by a wide area of dyking and associated hydrothermal alteration, in which phonolite and carbonatite dykes related to the intrusive plugs have exploited pre-existing structures in the basement that were re-activated during Neoproterozoic tectonism. The carbonatite dykes are widely mineralised with rare earth elements (REE). The total area affected by carbonatitic dykes and associated alteration and mineralisation is more than 200 km2.
The Area 4 resource is currently defined by delineation drilling to a depth of between 150 and 200 vertical metres. In form, the main mineralised zone (MMZ) is an irregular slab generally between 10 and 20 m thick that strikes approximately 70 to 75 and dips between 45 and 60 in a southerly direction. Additional zones of REE mineralisation with variable thickness occur 20 m to 40 m below the Main Mineralized Zone and 25 m to 30 m above the main mineralisation. These zones can currently not be classified as a resource but particularly the latter occurrence could potentially provide additional mineral resources in an opencast mining scenario. Four boreholes were drilled to intersect the projection of the MMZ below the current resource limits at between 250 m and 300 m vertical depth. All holes intersected alteration and mineralisation close to the down dip projection of the mineralised slab. There is currently not sufficient information at these depths to classify the down-dip extension of the mineralisation as resource. However, these holes are interpreted to demonstrate the continuity of the mineralised zone and to indicate that additional deeper drilling has the potential to substantially increase the dimensions of the resource.
Summary:
The proposed mining method is conventional open pit mining. Mineralised rock and waste would be drilled, blasted, loaded by hydraulic shovels and hydraulic excavators into off-highway dump trucks, and hauled to the processing plant.
The Main Zone of the Area 4 deposit would be mined at cut-off grade of 0.1% TREO which would require minimal in-pit grade control. Essentially, the entire mineralised zone would be mined. "Fine" in-pit grade control is expected to be difficult because of the nature of the mineralisation. The use of XRT after the crushing stage will deal with the separation of internal waste. It was therefore decided to not carry out a standard pit optimisation to guide the pit design.
Processing
- Acid tank leaching
- Magnetic separation
- X-Ray sorting
Source:
Summary:
Although testwork is still progressing at Mintek in Johannesburg, South Africa as well as Nagrom in Western Australia, this study compiled a flowsheet based on best data from testwork at the time of writing for a 2,500 t/d primary processing facility coupled to a remote xenotime cracking facility to remove radioactive thorium from the concentrate. The final concentrate will be shipped from the port of Walvis Bay, Namibia to processing facilities abroad.
The process plant will most likely consist of two locations with the primary beneficiation facility (Mill Site Process Plant) located at the mine site and the concentrate processing facility (Cracking Plant) located at the port of Walvis Bay. This will allow the key skills to be located in the town of Walvis Bay, which will facilitate easier attraction and retention of skills required for the relatively complex cracking facility. At present the calcite HCL leach facility is still located at the mine site but should this faci ........

Projected Production:
Commodity | Units | LOM |
Total Rare Earth Oxides
|
t
| 11,000 |
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 10.4 * |
Daily mining rate
| 2,500 t * |
Annual mining capacity
| 840,000 t * |
Waste tonnes, LOM
| 63.1 Mt * |
Total tonnes mined, LOM
| 6,042,000 t * |
Tonnes processed, LOM
| 6.04 Mt * |
* According to 2014 study.
Reserves at December 31, 2014:
Category | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
2.88 Mt
|
Total Rare Earth Oxides
|
0.32 %
|
9,234 t
|
Indicated
|
2.88 Mt
|
Light Rare Earth Oxides
|
0.08 %
|
2,185 t
|
Indicated
|
2.88 Mt
|
Heavy Rare Earth Oxides
|
0.24 %
|
7,049 t
|
Inferred
|
3.28 Mt
|
Total Rare Earth Oxides
|
0.27 %
|
8,973 t
|
Inferred
|
3.28 Mt
|
Light Rare Earth Oxides
|
0.07 %
|
2,271 t
|
Inferred
|
3.28 Mt
|
Heavy Rare Earth Oxides
|
0.2 %
|
6,702 t
|
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