Overview
| Stage | Permitting |
| Mine Type | Open Pit |
| Commodities |
|
| Mining Method |
|
| Processing |
- Flotation
- High Pressure Grinding Roll crusher
- Dense media separation
|
| Mine Life | 11 years (as of Jan 1, 2019) |
Source:
p. 17
n June 2019 the Group completed the acquisition of the minority 25% stake in the operating subsidiary, Savannah Lithium Lda which allowed the Group to take sole ownership of the Mina do Barroso project.
Summary:
The Barroso – Alvão Region is characterized by the presence of a large field of several dozen pegmatite and aplite-pegmatite dykes of granitic composition. Pegmatite dykes are mainly intruded in the granitic rocks of the region whilst aplite-pegmatite dykes are hosted by low- to medium-grade metasedimentary rocks of Silurian age that are strongly deformed (B. CHAROY et al.,1992). The thickness of these dykes ranges from less than 1m up to 50m.
The Li-rich aplite-pegmatite dykes show a spatial distribution of 3 sub-types (LIMA et al, 2003):
- Spodumene-rich aplite-pegmatite dykes and sills are dominant at N and NE regions;
- Petalite-rich are dominant at SW; and
- Lepidolite-rich occur at NW regions.
The Mina do Barroso Project is centred on a series of spodumene rich aplite-pegmatite dykes and sills which have formed the basis of this study.
Grandao Deposit: Mineralised zone over 500m long, 450m wide and pegmatite depths of up to 50m. Results from recent drilling has recorded the broadest and most significant results for the Project to date.
Reservatorio Deposit: Drilling has confirmed that the lithium mineralisation extends to over 400m strike length, with good down dip extensions of at least 100m.
NOA Deposit: Drilling has confirmed the presence of lithium mineralisation over a 200m strike length together with good down dip extensions of at least 50m.
Summary:
The Mina do Barroso project will have four surface workings/open pits: Grandao, Pinheiro, Reservatorio and NOA. [July 2020, The Mina do Barroso Project Economic and Development Impacts, p.21]
Mining Inventory
Conceptual open pit mine planning for the Mina Do Barroso Lithium Project was developed targeting an annual plant feed rate of 1.3Mtpa with an estimated average over the life of mine mill head grade of 1.02 %Li2O (diluted), with an average overall strip ratio of 5.2:1 (waste:ore ratio) and a resultant eleven plus year life of mine (LOM).
Three geological block models (one for each respective deposit) were provided and conceptual pit shells were generated using an optimisation software founded on the Lerchs Grossman algorithm.
The Mina do Barroso total site conceptual infrastructure stretches 5 km by 2.5 km over relatively steep and undulating terrain. All conceptual mine infrastructure and excavations developed in this study were restricted to:
- within tenement boundaries;
- minimised sterilisation of prospective target exploration zones;
- respected offset boundaries for major watercourses; and
- legacy travel routes (where available).
As the Project progresses further refinements to haul routing plans, waste rock storage management and pit staging should be targeted to take advantage of opportunities for reduced haulage capital and operating costs.
Quantities of bulk pegmatite are also included in the production plan as valuable material below the cut-off grade to be stockpiled and sold. A total of 2.7 Mt of this material has been identified.
Based on standard equipment production capacities the fleet is estimated to comprise:
- 120t excavator (year 5-11)
- 80t excavator (year 1-4)
- 60t excavator
- 60t dump trucks (year 1-4)
- 90t dump trucks (year 5-11)
- 45t Dozers
- Graders
- Water cart
- Hydraulic drill rigs.
Processing Technologies
- Flotation
- High Pressure Grinding Roll crusher
- Dense media separation
Flow Sheet:
Summary:
The processing of ore to produce concentrates will comprise several stages:
- Crushing: Multiple stage crushing and then milling utilising high-pressure grind rollers “HPGR” to a P80 -4mm/+0.5mm to prepare the ore to be to be fed to a DMS Circuit;
- Dense Media Separation Circuit: The DMS circuit will separate material based on its specific gravity, using fine ferrosilicon as a separation medium. The middling and tailing streams from the DMS circuit are directed to the ball mill circuit for fine grinding in preparation for floatation;
- Fine Grinding Circuit: The fine grinding circuit will reduce material produced by the DMS to a final product size of P80 =106 µm, suitable for flotation;
- Flotation Circuit: The milled ore will be subjected to four stages of spodumene flotation to recover a spodumene concentrate including one rougher stage and three cleaner stages. A conventional flotation methodology will be used;
- Tailings: Pulp discharged from the tailings ........
Recoveries & Grades:
| Commodity | Parameter | Avg. LOM |
|
Spodumene
|
Recovery Rate, %
| ...... |
|
Spodumene
|
Head Grade, %
| 1.07 |
|
Spodumene
|
Concentrate Grade, %
| ...... |
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Reserves at May 31, 2019:
Cut-off grade of Li2O is 0.5%. Lithium cut-off grade does not apply for quartz and feldspar.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Measured
|
6.6 Mt
|
Li2O
|
1.1 %
|
71,600 t
|
|
Measured
|
7.1 Mt
|
Quartz
|
32.6 %
|
2.32 Mt
|
|
Measured
|
7.1 Mt
|
Feldspar
|
42.8 %
|
3.05 Mt
|
|
Measured
|
6.6 Mt
|
Fe2O3
|
0.7 %
|
|
|
Indicated
|
8.4 Mt
|
Li2O
|
1 %
|
86,700 t
|
|
Indicated
|
6.3 Mt
|
Quartz
|
34.6 %
|
2.17 Mt
|
|
Indicated
|
6.3 Mt
|
Feldspar
|
42.6 %
|
2.67 Mt
|
|
Indicated
|
8.4 Mt
|
Fe2O3
|
0.7 %
|
|
|
Inferred
|
12 Mt
|
Li2O
|
1.1 %
|
127,600 t
|
|
Inferred
|
1 Mt
|
Quartz
|
30.9 %
|
0.3 Mt
|
|
Inferred
|
1 Mt
|
Feldspar
|
40.3 %
|
0.39 Mt
|
|
Inferred
|
12 Mt
|
Fe2O3
|
0.9 %
|
|
|
Total Resource
|
27 Mt
|
Li2O
|
1.06 %
|
285,900 t
|
|
Total Resource
|
27 Mt
|
Fe2O3
|
0.8 %
|
|
|
Total Resource
|
14.4 Mt
|
Quartz
|
33.4 %
|
4.79 Mt
|
|
Total Resource
|
14.4 Mt
|
Feldspar
|
42.6 %
|
6.11 Mt
|
Aerial view:
- Subscription is required.