This 2025 scoping study outlines a lithium processing flowsheet for the PPG Salars project in Salta Province, Argentina, employing solar pre-concentration followed by solvent extraction and purification to produce battery-grade lithium carbonate and lithium hydroxide monohydrate.
Report context
The October 2025 NI 43-101 scoping study for the PPG Salars presents a three-phase development plan for lithium production from brine resources at the Pozuelos and Pastos Grandes salars. The recovery methods section (Section 17) describes a processing route designed by Adinf and Ganfeng Lithium based in Santiago, Chile, drawing on test work results. The design targets 153,000 tonnes per annum of lithium carbonate equivalent (LCE) across three phases, with each phase producing 51,000 tonnes LCE comprising 40,000 tonnes of battery-grade lithium carbonate and 12,500 tonnes of lithium hydroxide monohydrate. Each phase processes 3,383,884 cubic metres per year of pre-concentrated brine feed. The study represents a scoping-level assessment; the project is not in operation.
Processing route
Brine extraction and solar pre-concentration
Brine extracted from production wells is pumped to solar evaporation ponds for pre-concentration. The pond system design for each phase uses four independent strings, each comprising eight ponds in series, where even-numbered ponds are separated by baffles rather than walls to avoid transfer pumps and reduce dilution water requirements. Each string ends with a smaller buffer pond.
The process design criterion for all phases is an evaporation rate of 7 millimetres per day (referred to water), seepage of 0.05 millimetres per square metre, and entrainment of 10 per cent weight by weight. Feed lithium concentration differs between phases: Phase 1 receives brine at 0.0462 per cent Li (weight/weight), while Phases 2 and 3 receive brine at 0.0355 per cent Li. All phases concentrate brine to 0.246 per cent Li (3.09 grams per litre lithium), with final plant feed adjusted to 3.05 grams per litre after dilution water addition for transport. The concentrated brine is transferred to covered reservoirs and then to the processing plant at a design rate of 11,635 tonnes per day over 300 operating days per year.
Pond availability is estimated at 90 per cent to accommodate salt harvesting operations. Crystallised salts, primarily sodium chloride, are harvested every one to two years using earthmoving machinery, with impregnated brine recovery to minimise lithium losses. Waste salts are discharged to a Tailings Management Area (TMA) stockpile. The total design pond area for Phase 1 is 13,379,680 square metres across four strings; for Phases 2 and 3, each phase requires 16,901,216 square metres. The report notes that pond layouts are preliminary and may change during final engineering.
Solvent extraction
Pre-concentrated brine is filtered and acidified to pH 1 with recycled 7 per cent hydrochloric acid before entering solvent extraction. The process uses five extraction production lines per phase, each with a nominal capacity of 10,000 tonnes per annum LCE. Each line employs 26-stage mixer-settler tanks configured as 6-stage extraction, 6-stage washing, and 13-stage stripping.
The organic phase consists of TIAP (Tri Isoamyl phosphate) and P507 (2-Ethylhexyl 2-Ethylhexyl phosphate) in a sulfonated kerosene diluent. Ferric chloride is pre-loaded onto the extractant before entering the system. Lithium is co-extracted with iron to form the complex [Li(TIAP)₂][FeCl₄]. The extraction operates at an organic-to-aqueous (O/A) ratio of 4 for extraction, 40 to 66.7 for washing, and 20 for stripping. Extraction recovery is reported as 90 per cent.
After water stripping, a lithium chloride solution with lithium content of at least 19 grams per litre is obtained. The strip solution analysis shows 19.34 grams per litre Li, with minor concentrations of magnesium (0.007 g/L), calcium (0.03 g/L), sodium (0.172 g/L), potassium (0.014 g/L), and boron (1.96 g/L). The raffinate contains 0.3 grams per litre residual lithium.
Raffinate treatment
Depleted brine (raffinate) from solvent extraction undergoes organic removal via resin adsorption. The raffinate is adjusted to pH 7 with sodium hydroxide, then passed through an 8-stage resin adsorption system to reduce total organic carbon (TOC) to 30 ppm or less. Regeneration liquids from the resin system are treated through a biochemical degradation process comprising a Fenton reactor, catalytic oxidation, anaerobic treatment, and contact oxidation, reducing chemical oxygen demand (COD) to below 20 ppm. Treated wastewater is recycled for brine dilution during pre-concentration. After organic removal, the raffinate is sent to the salar via pond/infiltration/evaporation.
Primary purification
The lithium chloride solution undergoes two primary purification steps:
Boron removal: The strip solution is treated with lime (calcium oxide) at 70–80°C at a calcium-to-boron molar ratio of 1.2:1. Boron concentration decreases from less than 3 grams per litre to 0.31 grams per litre, with lithium loss reported as less than 0.5 per cent. The solid waste calcium borate is sent to a storage yard. The de-boronised solution shows 19.11 grams per litre Li and 0.31 grams per litre B.
Calcium removal: The de-boronised solution reacts with sodium carbonate at 75°C to precipitate calcium carbonate, reducing calcium concentration to 10 ppm. The resulting solution analyses at 18.98 grams per litre Li, 0.302 grams per litre B, and 0.009 grams per litre Ca. Solid calcium carbonate residue is disposed of in a dedicated storage area of approximately 7,916 square metres with a maximum height of 10 metres, providing about 36,000 cubic metres storage.
Secondary purification
Secondary purification comprises several ion exchange and resin steps:
Carbonate removal: The primary purified brine is acidified to pH 1 with recycled 7 per cent HCl to remove carbonate, then neutralised to pH 7 with recycled 7 per cent LiOH.
TOC removal: Resin adsorption in three columns in series (each with 10 cubic metres of resin) reduces TOC to 10 ppm. Resin is regenerated with 7 per cent sodium hydroxide solution, neutralised with 7 per cent HCl, and sent to biochemical treatment.
Calcium removal: Chelating resin removes calcium to below 1 ppm.
Boron removal: A dedicated boron-selective resin system with two columns in series and one standby removes boron to zero grams per litre. The regeneration process includes displacement, water washing, acid desorption with 7 per cent HCl, a second water wash, and resin regeneration with 7 per cent LiOH. Regeneration liquids are sent to the ponds.
After secondary purification, the purified brine stream is split: one portion (25.16 tonnes per hour) goes to bipolar membrane electrodialysis for lithium hydroxide production, while the other (57.42 tonnes per hour) goes to the lithium carbonate plant.
Lithium hydroxide via bipolar membrane electrodialysis
The purified lithium chloride solution enters a bipolar membrane electrodialysis system, where chloride ions migrate through an anion membrane to form hydrochloric acid, while hydroxide ions combine with lithium ions to form lithium hydroxide. The overall reaction is LiCl + H₂O → LiOH + HCl. The resulting lithium hydroxide solution (7 per cent LiOH, 21.5 grams per litre Li) is concentrated and crystallised in a mechanical vapour recompression (MVR) evaporator-crystalliser. The crystal slurry undergoes centrifugal separation, drying, and packaging to produce lithium hydroxide monohydrate.
Lithium carbonate precipitation
The remaining purified lithium chloride solution (or the calcium-free solution from primary purification, as the flowsheet indicates the carbonate plant receives the calcium removal output) reacts with a 220 grams per litre sodium carbonate solution preheated to 80°C. Precipitation occurs at 85°C with a LiCl-to-Na₂CO₃ molar ratio of 1:0.525. After centrifugal separation, drying, and micronisation, battery-grade lithium carbonate is obtained. The mother liquor is acidified, neutralised, and recycled to improve overall lithium recovery.
Key reported parameters
| Parameter | Value | Unit | Basis / Phase |
|---|---|---|---|
| Nominal annual production per phase | 51,000 | t/y LCE | Design: 40,000 t/y Li₂CO₃ + 12,500 t/y LiOH·H₂O |
| Pre-concentrated brine feed per phase | 3,383,884 | m³/y | Design |
| Pre-concentrated brine rate | 11,635 | t/d | Design, 300 d/y, each phase |
| Pond feed lithium concentration (Phase 1) | 0.0462 | % w/w Li | Raw brine analysis |
| Pond feed lithium concentration (Phases 2/3) | 0.0355 | % w/w Li | Raw brine analysis |
| Concentrated brine lithium | 0.246 (3.09 g/L) | % w/w Li | Pond outlet design |
| Plant feed lithium concentration | 3.05 | g/L | After dilution water addition |
| Pond evaporation rate | 7 | mm/d | Design criterion (water basis) |
| Pond availability | 90 | % | Design allowance for harvesting |
| Solvent extraction recovery | 90 | % | Design |
| Solvent extraction stages per train | 26 (6 extraction, 6 washing, 13 stripping) | stages | Design, 5 trains per phase |
| Extraction O/A ratio | 4 | , | Design |
| Stripping O/A ratio | 20 | , | Design |
| Strip solution lithium concentration | ≥19 (measured: 19.34) | g/L | Design / testwork |
| Boron removal: feed to product B concentration | <3 → 0.31 | g/L | Design |
| Boron removal: Li loss | <0.5 | % | Reported |
| Calcium removal: product Ca concentration | 10 | ppm | Design target |
| Secondary purification: TOC target | ≤10 | ppm | Design |
| Secondary purification: Ca target | ≤1 | ppm | Design |
| Carbonate precipitation: LiCl:Na₂CO₃ molar ratio | 1:0.525 | mol/mol | Design |
| Carbonate precipitation temperature | 85 | °C | Design |
| Electrodialysis product LiOH concentration | 7 (21.5 g/L Li) | % w/w | Design |
| Salt production (Phase 1) | 5,153,241 | t/y | Design, harvested pond salts |
| Salt production (Phases 2/3, each) | 4,921,674 | t/y | Design |
Project website: https://investors.lithium-argentina.com/news-releases/news-release-details/lithium-argentina-and-ganfeng-announce-ppg-scoping-study-results
Technical qualifications
This profile is based solely on the recovery methods section (Section 17) of the October 2025 NI 43-101 scoping study for the PPG Salars. The study is a scoping-level assessment, not a feasibility study; all process parameters represent proposed design criteria, not operating data. Pond layouts are explicitly described as preliminary and subject to change during final engineering. The report notes that geotechnical and topographic studies for pond and TMA locations should be conducted in the next engineering phase. Solvent extraction chemistry and reagent consumption figures are derived from test work; overall process recovery figures are not consolidated in the cited sections. The flowsheet distinguishes between a 2024 lithium carbonate scheme (which may show different recycles) and a 2025 lithium chloride scheme. Industrial-grade lithium carbonate is not considered; only battery-grade products are envisioned. No mineral reserve estimates, economic analysis, or detailed resource calculations are included in the cited sections.
Source: NI 43-101 Technical Report, Scoping Study Report, PPG Salars, Salta Province, Argentina, effective date October 31, 2025, filing date December 18, 2025. Section 17: Recovery Methods.
