This review summarizes the process design for the Falchani Lithium Project, covering its phased production strategy, key unit operations, and design criteria for the Base Case and Alternate Case processing schemes.
The Falchani Lithium Project consists of an open pit mine and an associated processing facility designed to treat lithium-bearing tuff mineralized material. The process plant design is based on achieving a peak milled tonnage of 6 Mt/y over three phases, with a total mine life of 43 years. The project produces lithium carbonate (LC) at a minimum purity of 99.5%, with a total of 2.6 Mt of LC product generated over the life of mine at a lithium recovery of 80%.
The processing facility utilizes sulfuric acid leaching under atmospheric conditions, followed by purification steps including neutralization, softening, ion exchange, and lithium carbonate precipitation. Two process configurations are described: the Base Case and the Alternate Case, the latter including additional by-product recovery circuits for potassium and cesium. The Base Case plant includes mineralized material handling, crushing and grinding, acid leaching, pre-neutralisation, neutralisation, softening, evaporation, ion exchange, lithium carbonate precipitation and product handling, potassium/sodium sulfate crystallisation, dry stacked filtered tailings, and services and utilities. The Alternate Case adds mixed alum dissolution and SOP neutralisation areas.
Design criteria provide key parameters for the process, including phased throughputs, lithium head grades, production rates, and reagent consumptions. Power and water consumption figures are presented as design estimates, with the Alternate Case projected to have higher requirements due to additional by-product recovery circuits.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Life of Mine | 43 | Years | Not stated |
| Plant Design Throughput (Phase 1, Year 1-5) | 1,500,000 | Tonnes/year | Not stated |
| Plant Design Throughput (Phase 2, Year 6-10) | 3,000,000 | Tonnes/year | Not stated |
| Plant Design Throughput (Phase 3, Year 11-43) | 6,000,000 | Tonnes/year | Not stated |
| Operating Hours Per Year | 8,000 | Hours | Not stated |
| Lithium Head Grade (Year 1-32) | 3,380 | ppm | Not stated |
| Lithium Head Grade (Year 33-43) | 1,841 | ppm | Not stated |
| Lithium Production (Year 1-5 steady state) | 23,000 | Tonnes/year | Not stated |
| Lithium Production (Year 6-10 steady state) | 45,000 | Tonnes/year | Not stated |
| Lithium Production (Year 11-32 steady state) | 84,000 | Tonnes/year | Not stated |
| Lithium Production (Year 33-43, Stockpile) | 44,800 | Tonnes/year | Not stated |
| Leach Method | , | , | Acid Leach |
| Acid Addition per Tonne of Mineralized Material | 387 | kg | Not stated |
| Lithium Recovery | 80 | % | Not stated |
| Lithium Carbonate Purity | 99.5 | % | Minimum |
| Total LC Production Over Life of Mine | 2.6 | Mt | Not stated |
Project website: https://americanlithiumcorp.com/falchani-lithium-project-peru/
Overview
The Falchani Lithium Project involves mining lithium-bearing tuff and processing it through a hydrometallurgical plant. The process design was developed based on key parameters including ore requirements, recoveries, reagent consumptions, and temperatures. The phased production strategy is detailed in the process rate table, showing an expansion from 1.5 Mt/y in Phase 1 to 6.0 Mt/y in Phase 3.
The project has two process configurations. The Base Case focuses on lithium carbonate production. The Alternate Case incorporates additional circuits for by-product recovery, including potassium sulfate (SOP) and cesium-rich mixed sulfate. These additional circuits increase the plant footprint and utility requirements.
Key Process Stages
The process plant is organized into multiple work areas, each with specific functions. Area 100 covers crushing, where mined mineralized material is stockpiled and fed through a feed hopper using a front end loader. The material passes over a scalping screen, with undersized particles falling onto the feed conveyor. Secondary and tertiary crushers operate in closed circuit, with discharge returning to the feed conveyor for further screening.
Area 200 covers milling. A conveyor feeder at the bottom of the crushed mineralized material bin regulates flow to the ball mill. The crushed material is ground with the aid of process water. The mill discharge is pumped to leach filters to separate the leach liquor from the unleached material.
Acid leaching (Area 400) involves atmospheric sulfuric acid leaching where lithium and other elements are dissolved. The leach slurry is pumped to leach filters to separate the liquor from the solid residue. The solids are repulped with process water and pumped to the tailings tank.
Pre-neutralisation (Area 500) and neutralisation (Area 600) involve staged reactions to remove impurities. Precipitated solids undergo washing with process water to recover entrained lithium. A portion of the iron removal (IR) clarifier underflow is recycled to seed subsequent precipitation reactions. Slurry overflows through tanks via overflow weirs and launders.
Softening (Area 700) uses a series of agitated tanks to precipitate remaining impurities. The resulting slurry is processed through a centrifuge to separate the liquor.
Evaporation (Area 900) reduces solution volume and increases lithium concentration. Ion exchange (Area 900) purifies the solution, with the purified eluate pumped to product precipitation.
Product precipitation (Area 900/1000) involves lithium carbonate precipitation and product handling. Potassium/sodium sulfate crystallisation produces salt crystals that are dried and conveyed to stockpile. Barren solution bleed reports to tailings neutralisation tanks where limestone and slaked lime are added.
Tailings (Area 1100) are neutralized in a two-tank system before pumping to the dry stacked filtered tailings area.
The sulfuric acid plant converts solid sulfur to approximately 98% sulfuric acid using a double absorption process. The acid is stored in two tanks and pumped to the processing plant in a duty/standby configuration. Sodium carbonate is delivered as solid salt. Slaked lime is added to both neutralisation and tailings circuits.
Additional Interesting Data and Summary
The process design includes an acid plant that generates power. The Base Case has a calculated unit power draw of 76.4 kWh/t of mineralized material. The Alternate Case raises the power draw due to additional by-product recovery circuits, requiring grid power due to insufficient acid plant power generation. Raw water make-up in the Alternate Case increases water demand by 1.14 cubic meters per tonne.
The leach filtration circuit uses a washate system to recover entrained lithium. Leach filters separate the leach liquor from unleached materials, and washate is returned to the process water tank. The process demonstrates a closed-loop approach to water and reagent management.
The project includes dry stacked filtered tailings, which involves neutralizing waste slurry from neutralisation, pre-neutralisation, and softening circuits. Limestone and slaked lime are added to neutralize remaining acid before the slurry is pumped to tailings.
Key Processes
- Atmospheric sulfuric acid leaching for lithium dissolution
- Staged neutralisation for impurity removal
- Softening circuit for calcium and magnesium removal
- Evaporation and ion exchange for lithium concentration and purification
- Lithium carbonate precipitation with 99.5% minimum purity
- Potassium and sodium sulfate crystallisation
- Cesium-rich mixed sulfate recovery (Alternate Case)
- Dry stacked filtered tailings with neutralisation
- Sulfuric acid production via double absorption plant
Source: Falchani Lithium Project , Process Design Report, 2023. Project website: Falchani Lithium Project
Project website: Falchani Lithium Project, Process Design Report
