The Finniss lithium project is a high-grade lithium mine being developed near Darwin in Northern Territory, Australia.
Core Lithium is developing the project, for which the pre-feasibility study (PFS) was completed in June 2018 and the definitive feasibility study (DFS) was completed in April 2019.
Construction of the project is expected to be commenced in the second half of 2019, with the increased commercial production scheduled for the first half of 2020. The mine is estimated to produce 481,000t of high-quality 5% spodumene concentrate for export, through its initial mine life of 3.5 years.
The Finniss lithium project is located within granted mineral lease ML 31726, which extends in 768 hectares (ha). It is located entirely on and surrounded by undeveloped Vacant Crown Land.
The mine encompasses five deposits namely Grants, Carlton, Sandras, Hang Gong SW, and BP33. The project area is made up of 500km² of tenements covering the Bynoe pegmatite field (BPF) and comprising several pegmatites near Darwin.
The mineralisation is hosted within pegmatites, which are identified to be of lithium-caesium-tantalum (LCT) type. The pegmatites are estimated to have formed from the Ma S-Type Two Sisters Granite. Major pegmatites discovered at the Grants and BP33 are composed of coarse spodumene, quartz, albite, microcline, and mica.
The proven and probable reserves of Finniss lithium project are estimated at 2.2Mt, grading 1.4% Li2O.
The project is estimated to contain 32,200t of lithium and forecasted to hold mineral resources of 8.85Mt, grading 1.3% Li2O.
The Finniss project will be mined using open-pit methods. The Grants deposit is to be mined in two stages with an initial pit followed by a final cut-back while the BP33 deposit will be developed in a single stage.
The project will feature a three-stage dense media separation (DMS) plant, which is expected to treat one million tonnes per annum (Mtpa) of spodumene bearing pegmatite. It will also be installed with a reflux classifier and mica removal circuit, in addition to the DMS plant.
The project is expected to produce up to 180,000 tonnes per annum (tpa) of high-quality lithium concentrate. Ore will pass through a four-stage crushing circuit, designed to crush to a size of 6.3mm. The coarse material will undergo secondary DMS, followed by re-crushing of the DMS middlings.
A primary and a secondary DMS circuit will be used to further process the coarse ore, with the resulting DMS floats to be further re-crushed and recycled. Fines will be separated from the final product.
Spodumene concentrate produced at Finniss will be transported to the Darwin Port for delivery to customers.
Core Lithium has entered an offtake agreement with Ya Hua International Investment and Development (Yahua) for the sale of 75,000tpa of 5.5% Li2O concentrate produced at Finniss.
Sichuan Yahua Industrial Group subsidiary Yahua will receive 300,000 dry metric tonnes of Li2O concentrate from Finniss under the agreement, which is valid until November 2023.
Power supply for the project will be generated on-site, while the required water will be collected from the nearby observation hill dam (OHD) and a dam located to the west of the project.
Primero is responsible for the engineering aspect of the Finniss lithium project DFS, while Dr Graeme McDonald prepared the mineral resource estimates and ore grade variability modelling.
TME is responsible for the mine planning & scheduling, and mining, and also supported Core and Proactive Mining Solutions in preparing the ore reserves.
Other consultants involved in the DFS preparation were GHD, Cable Blu, Argonaut, Trilabs, Outotec, and Nagrom.
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