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 a potential to deliver high purity (99.97%) lithium carbonate.

The project is fully owned by Lake Resources through its Argentine subsidiary, Morena del Valle Minerals.

A pre-feasibility study (PFS) for the project was released in April 2020 while the definitive feasibility study (DFS) was started in January 2021 with a demonstration plant expected to be commissioned at the project site by the end of 2021.

The project is expected to require a capital investment of approximately £400m ($544.4 million) while the project life is estimated to be 25 years.

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 a total area of approximately 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.

Mineralisation and reserves

The brine mineralisation at the Kachi lithium project is spread over approximately 175km2 with depths extending up to 400m.

The Kachi lithium brine project was estimated to hold approximately one million tonne (Mt) of indicated lithium carbonate equivalent (LCE) resources containing at 290 mg/l of lithium and 3.4Mt of inferred LCE resources containing 210 mg/l of lithium as of April 2020.

Brine extraction and lithium processing

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. The suspended solids from the brine will be removed by filtration and then be 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 further concentration by reverse osmosis (RO) before it is 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.

Contractors involved

Lilac Solutions was engaged for the design and engineering of the direct extraction plant for the project.

Hatch was engaged as the lead consultant for the definitive feasibility study (DFS) of the project that was initiated  in January 2021.