Overview
Status | Care and Maintenance |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Wet Screening
- Dewatering
- Flotation
- Dense media separation
- Magnetic separation
|
Mine Life | 24 years (as of Jan 1, 2019) |
The acquisition of Altura Lithium Operations (Altura) in January 2021, resulted in a further 1.3 Mtpa ore throughput capacity, although currently not operating, via the renamed Ngungaju processing plant for a combined Pilgangoora processing throughput capacity of 3.6 Mtpa from CY 2022. The Ngungaju plant is to be restarted in late CY 2021. |
Latest News | Pilbara Minerals strengthens Pilgangoora lithium foothold January 21, 2021 |
Source:
p. 1
JANUARY 20, 2021 - Pilbara Minerals Limited (ASX: PLS) is pleased to announce it has completed the acquisition of the Altura Project. The Company has acquired all of the shares in Altura Lithium Operations Pty Ltd (ALO), the entity which owns the Altura Lithium Project.
Summary:
Altura’s Pilgangoora Lithium Project occurs at the southern end of a zone of pegmatite intrusive dykes within the synformal Pilgangoora greenstone belt. The pegmatites are hosted within amphibolites which have a mafic and ultramafic volcanic origin. A total of 13 mineralised pegmatites have been identified and these occur as a set of stacked lodes generally striking 010 030oNNE and dipping 25-40oESE. The dykes generally range from 8-14m thick however there are areas where the pegmatites form lenticular pods and are much thicker (up to 64m).
Based upon the completed drilling, the pegmatites appear to be confined to a NNE trending corridor which is approximately 1600 metres long (north to south), 550 metres wide (east to west) and 450m deep. Mineralisation is present at surface for some lodes with most mineralised lodes starting from within 10m of surface.
The mineralised pegmatites are located approximately 1km east of a granite contact. There are several barren pegmatites located in the zone between the granite contact and the mineralised pegmatite zone. The granite contact and barren pegmatites were identified via sterilisation drilling carried out for the proposed infrastructure and waste dump areas.
The reason for this structural and or geological control within the deposit area is not fully understood however the distance from the granite contact is such that mineralisation in the pegmatite is confined to lithium and rubidium (almost wholly reporting in spodumene and muscovite respectively) with relatively low values for tin and tantalum or other associated minerals.
Summary:
Mining will be undertaken by conventional bulk mining methods utilising EX2500 hydraulic excavators, CAT785 dump trucks and drill and blast delivering ore to a ROM stockpile. Ore will be trucked directly from the blasted faces to the ROM stockpile and fed to the primary crusher using a Front-End Loader (FEL). There has been allowance made for blending from the ROM and external stockpiles. The mining operation is 12-hour shifts with crews working day shift and night shift once Stage 2 operations begin to ramp up.
The pits will be mined using 3m flitches for ore and waste. This height gives reasonable production efficiency while keeping dilution to a minimum. In waste, the flitch height could be increased to improve efficiency within the limits of the equipment size.
Pit Design Parameters:
- Bench Height - 6 m;
- Batter Angle - 75 Degrees;
- Stack Height - 12 m;
- Stack Berm Width - 10 m;
- Inter-ramp Angle (IRA) - 42.25 Degrees;
- Geotechnical Catch berm interval - 80 m;
- Catchment Berm Width - 15 m;
- Ramp Width - 24 m.
All haul roads used by mine equipment need to accommodate a Caterpillar 785, 130t dump trucks. The main ramps with an overall width of 3.5-4 times the truck width using a 10% gradient. This allows for safe passing of trucks inclusive of wall side drainage and pit side bunding. For the benches at the pit bottom (up to 40 metres overall height), a single lane ramp running width of 2.0 times the truck width was adopted at 10% gradient to reflect the lower traffic intensity on this section of the ramp and to minimise waste development.
All mine waste rock will be dumped external to the pit. Waste rock dumps have been designed to allow the LOM waste volumes.
Within the open pit, water will be managed via ditching on benches and through sumps in the pit floor. The actual drain requirements will be assessed during operations based on the performance of the dewatering system as the requirements are likely to vary with mine depth. Flooding of the lower operating bench following rainfall will be removed via a pumping system to either turkey’s nests for use in dust suppression or to the overall site raw water storage system.
A total of 6 mining stages plus a Hilltop stage were developed for the mining sequence within the final pit.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
1
|
High Pressure Grinding Rolls (HPGR)
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Summary:
The Stage 2 processing plant is designed to process an anticipated 1.54Mtpa of mined pegmatite ore. The ore is crushed to 28mm through a closed crushing circuit utilising a primary jaw crusher, secondary cone crusher and dry vibrating screen. The -28mm material is stockpiled to delink the crushing circuit from the remainder of the plant. The ore is then crushed with High Pressure Grinding Rolls (HPGR) to reduce the particle size to -6mm and wet screened to a 6x1mm DMS feed and -1mm fines fraction.
Processing
- Wet Screening
- Dewatering
- Flotation
- Dense media separation
- Magnetic separation
Flow Sheet:
Summary:
The Stage 2 Processing plant is a duplicate of the Stage 1 plant with some minor exceptions to suit the topography and existing infrastructure that will be utilised. Otherwise all is as per the Stage 1 plant to reduce the need for redesign.
The process design for the Stage 2 Plant is as per Stage 1 and its main components are outlined below:
• Two-stage crushing and dry screening circuit;
• HPGR tertiary crushing and wet screening plant to produce a 6 x 1mm crushed product size and -1mm fines stream;
• Mica removal on both the above streams prior to processing;
• Dense Media Separation (DMS) on the coarse 6 x 1mm fraction producing a coarse spodumene product;
• Milling and flotation circuit to produce an on-grade fine spodumene product;
• Magnetic separation to separately remove iron contamination from the coarse and fine concentrate.
The Stage 2 processing plant is designed to process an anticipated 1.54Mtpa of mined pegmatite or ........

Recoveries & Grades:
Commodity | Parameter | 2020 | 2019 |
Spodumene
|
Head Grade, %
| ......  | ......  |
Reserves at June 30, 2019:
Mineral resource and ore reserve estimate at 0.30% Li2O cut-off grade.
A revised Mineral Resource and Ore Reserve Estimate for the Pilgangoora Altura Lithium Project whilst being prepared as a matter of routine business, was not released in 2020 due to the events initiated in late October 2020.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
7.2 Mt
|
Li2O
|
1.22 %
|
87,000 t
|
Proven
|
7.2 Mt
|
Fe2O3
|
1.4 %
|
|
Probable
|
30.5 Mt
|
Li2O
|
1.05 %
|
320,000 t
|
Probable
|
30.5 Mt
|
Fe2O3
|
1.29 %
|
|
Proven & Probable
|
37.6 Mt
|
Li2O
|
1.08 %
|
407,000 t
|
Proven & Probable
|
37.6 Mt
|
Fe2O3
|
1.31 %
|
|
Measured
|
7.4 Mt
|
Li2O
|
1.23 %
|
91,000 t
|
Measured
|
7.4 Mt
|
Fe2O3
|
1.38 %
|
|
Indicated
|
34.2 Mt
|
Li2O
|
1.03 %
|
353,000 t
|
Indicated
|
34.2 Mt
|
Fe2O3
|
1.29 %
|
|
Measured & Indicated
|
41.6 Mt
|
Li2O
|
1.07 %
|
444,000 t
|
Measured & Indicated
|
41.6 Mt
|
Fe2O3
|
1.31 %
|
|
Inferred
|
4.1 Mt
|
Li2O
|
0.95 %
|
39,000 t
|
Inferred
|
4.1 Mt
|
Fe2O3
|
1.41 %
|
|
Total Resource
|
45.7 Mt
|
Li2O
|
1.06 %
|
483,000 t
|
Total Resource
|
45.7 Mt
|
Fe2O3
|
1.32 %
|
|
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