The Kachi lithium brine project, located in Salar de Carachi Pampa, Argentina, is considered to be one of the world’s top ten brine resources with the potential to deliver high-purity (99.97%) lithium carbonate. The project is fully owned by Australian lithium company Lake Resources through its Argentine subsidiary, Morena del Valle Minerals. A pre-feasibility study (PFS) of the project was released in April 2020, while a definitive feasibility study (DFS) was started in January 2021. While the DFS and an environmental and social impact assessment (ESIA) are targeted for completion in the second quarter of 2022, a demonstration plant at the project site is scheduled for commissioning in the first quarter of 2022. The Kachi project is expected to involve a capital investment of £400m ($544.4m) and produce up to 25,500 tonnes (t) of lithium carbonate equivalent (LCE) a year starting from 2024. The project life is estimated to be 25 years.
Kachi lithium project location and geology
The Kachi lithium brine project is located approximately 45km south of Antofagasta and 22km west of the town of El Peñon, in the Puna region in north-western Argentina. The project area encompasses 37 mineral exploration leases covering 70,000 hectares over the centre and southern extension of the Carachi Pampa salt lake or the Salar de Carachi Pampa.
A pliocene basaltic shield volcanic cone overlies the Carachi Pampa salt lake basin infill sediments with lava flow, scoria, and air fall basaltic debris. The brine-saturated basinal sediments to the south are covered by ignimbrites and unconsolidated pyroclastic sediments of the Cerro Blanco Pyroclastic Complex.
Kachi lithium mineralisation and reserves
The brine mineralisation at the Kachi lithium project is spread over 175km2 with depths extending up to 400m.
The Kachi lithium brine project was estimated to hold one million tonne (Mt) of indicated LCE resources and 3.4Mt of inferred LCE resources as of April 2020.
Brine extraction and lithium processing for the Kachi project
The Kachi lithium brine project will utilise a network of wells to extract the brine from the salt flat, which will be piped to a brine storage pond. Suspended solids from the brine will be removed by filtration and then processed in the direct extraction plant.
The lithium contained in the brine solution will be recovered and passed through ion exchange to produce an eluate stream in the direct extraction plant. The depleted brine from the direct extraction plant will be injected back into the salar.
The eluate stream will undergo concentration using reverse osmosis (RO) before being introduced into the lithium carbonate plant for further processing to produce the final lithium carbonate product.
The lithium processing plant will have a target production capacity of 25,500 tonnes per annum (tpa) of battery-grade lithium carbonate with an overall plant recovery rate of 83.2%. The concentrated eluate will be purified and treated with sodium carbonate to produce a solid precipitate of lithium carbonate, which will be separated through filtration. The final product will be dried, milled, and packaged for shipment.
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