Name of the Project
Pilgangoora lithium Phase 2 expansion project.

Location
Western Australia.

Client
Altura Mining Limited.

Project Description
A definitive feasibility study (DFS) on Stage 2 of the Pilgangoora project has demonstrated that expanding output will add significant project value over a short period.

The Stage 1 DFS has provided the foundation upon which the Stage 2 DFS has been concluded.

The project has mineral reserves of 34.2-million tonnes, grading 1.04% lithium oxide (Li₂O) and 2.16% iron oxide (Fe₂O₃). Measured and indicated mineral resources have been estimated at 44-million tonnes, grading 1% Li₂O and 2.01% Fe₂O₃. Inferred resources have been estimated at 3.5-million tonnes, grading 0.84% L_i2O.

The expansion of the operation will result in the production of 440 000 t/y of Li₂O spodumene concentrate.

Mining will be undertaken by conventional bulk mining methods using hydraulic excavators, dump trucks and drill-and-blast delivering ore to a run-of-mine (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. Allowance has been made for blending from the RoM and external stockpiles.

The pits will be mined using 3 m 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.

The Stage-2 processing plant is a duplicate of the one proposed for the Stage-1 plant, with some minor exceptions to suit the topography and existing infrastructure that will be used.

The process design for Stage 2 includes:

a two-stage crushing and dry screening circuit;

high-pressure grinding rolls (HPGR) tertiary crushing and wet screening plant to produce a 6 mm × 1 mm crushed product size and–1 mm fines stream;

mica removal on both of the aforementioned streams before processing;

dense-media separation (DMS) on the coarse 6 mm × 1 mm fraction, producing a coarse spodumene product;

a milling and flotation circuit to produce an on-grade fine spodumene product; and

magnetic separation to separately remove iron contamination from the coarse and fine concentrate.

RoM ore will be delivered by haul trucks and dumped on the RoM pad. Provision has been made for numerous RoM stockpiles at different grades to allow for feed blending to optimise plant performance.

The Stage 2 processing plant is designed to process an estimated 1.54-million tonnes a year of mined pegmatite ore. 

The ore is crushed to 28 mm through a closed crushing circuit using a primary jaw crusher, secondary cone crusher and dry vibrating screen. The –28 mm material is stockpiled to delink the crushing circuit from the remainder of the plant. The ore is then crushed using HGPRs to reduce the particle size to –6 mm and wet-screened to a 6 mm × 1 mm DMS feed and –1 mm fines fraction.

Mica is removed from the DMS feed by classification before a two-stage DMS plant, producing a high-density on-grade spodumene product, medium-density middlings and low density, rejects streams. 

The –1 mm fines from the HPGR is subject to further classification to remove mica before further processing.

Middlings from the DMS and preconcentrated fines will be transported to a closed-circuit ball mill to reduce the particle size to a P80 of 106 μm. The milled ore will be deslimed, removing the –20 μm fines before progressing to the flotation circuit. A rougher cleaner and recleaner circuit will upgrade the fines to an on-grade +6% Li2O concentrate.

The flotation concentrate is subject to high-intensity magnetic separation to reduce iron levels in the concentrate. The fine concentrate is dewatered and stockpiled for blending with the coarse concentrate before shipping.

The project will have a mine life of 30 years.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project has an after-tax net present value, at a 10% discount rate, of A$834.6-million and an internal rate of return of 62.6%, with a payback of 2.3 years.

Value
Capital costs for the project have been estimated at A$118-million.

Duration
Not stated.

Latest Developments
Altura Mining remains focused on commissioning Stage 1 as planned, which will allow for a formal investment decision to move to Stage 2 reaching total nameplate production of 440 000 t/y in early 2020.

Key Contracts and Suppliers
Cube Consulting (revised geological wireframe model and resource estimation).

On Budget and on Time?
Not stated

Contact Details for Project Information
Altura Mining, tel +61 8 9488 5100 or email cosec@alturamining.com.