Lithium is found in a number of different geological deposit types. The most common are pegmatite bodies, associated with granitic intrusive rocks, and continental brines in salt lakes (salars).

Continental lithium brines in salars settings (salt lakes) are found principally in Argentina, Chile, Bolivia and China, with lithium carbonate or lithium chloride produced from these projects. Lithium is rarely found in continental oilfields, where the accompanying produced water is enriched in lithium, probably deriving lithium from evaporite sequences in the stratigraphy.

Lithium brine projects can also be subdivided into two broad ‘deposit types’ with different characteristics (Houston et. al., 2011), which consist of:
• Mature salars (those containing extensive thicknesses – up to hundreds of meters - of halite (salt), such as the Salar de Atacama (Chile), and the Livent Hombre Muerto operation (northern Catamarca, Argentina); and
• Immature salars, which are dominated by clastic sediments, with limited thicknesses of halite, such as the Olaroz salar in Jujuy Argentina and the Silver Peak deposit in Nevada, USA, where brine is extracted from porous volcanic ash units.

Immature salars
Immature salars conversely have brine hosted in pore spaces controlled by the porosity and permeability associated with individual layers within the salar sequence. A degree of compaction occurs with increasing depth below surface, but unlike in matur ........

Lithium bearing brine hosted in pore spaces within sediments in the salar will be extracted by pumping using a series of production wells to pump brine to evaporation ponds for concentration of the brine. The Olaroz Project currently produces brine from two wellfields with wells installed to 200 m depth, with a number of other production wells installed to 350 and 450 metres deep.

Installation of wells for the expansion of the Olaroz Project is currently underway, with a total of 15 production wells planned between depths of 450 and 650 metres, depending on the location in the salar. The expansion wells will fill in the space between the existing northern and southern wellfields in the centre of the salar. Wells consist of stainless steel screen sections and carbon steel casing sections, designed based on geological and geophysical logging to maximise inflow into the wells. Pumps are individually selected for each well, depending on the performance of the well during the variable rate (step) and constant rate tests.

The Olaroz Stage 2 expansion is designed to deliver an additional 25,000 tonnes per year of technical grade lithium carbonate production capacity. Approximately 9,500 tonnes of this new production will be utilised as feedstock for the Naraha Lithium Hydroxide Plant in Japan.

First production was achieved in mid-July 2023, with wet lithium carbonate cake produced at the filter presses. The ongoing focus will be commissioning of the ........

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