The PEA update describes a proposed process plant with two identical trains processing ionic clay ore through ion exchange, counter-current decantation, and a closed-circuit water recovery system.
Report context
This Preliminary Economic Assessment (PEA) update for the Carina Rare Earth Element Project, dated May 3, 2024, was prepared by Aclara Resources Mineração Ltda. The report presents a proposed processing facility design based on 202 drillholes that inform the extraction plan, ore flow, REE grades, and recoveries. The document includes process flow diagrams and plant layout figures sourced from Promet101 (2024) and GE21 (2024).
Processing route
Plant configuration and feed
The proposed process plant will comprise two separate, identical trains or process lines. Each train will process 50% of the run-of-mine (ROM) feed material at a rate of 700 t/h on a wet basis. The total processed wet mineral feed rate is 1,400 t/h, with a dry mineral feed rate of 1,204 t/h and fresh mineral moisture content of 14.0%. The average REE grade in the feed is 1,071 ppm.
Ore preparation and conditioning
Ore from the mine is processed through static grizzlies to remove oversized material. A temporary stockpile is used when the plant is offline for maintenance. Ore passing through the grizzlies is conveyed to a lump breaker and then to a washing drum. After washing, coarse particles are removed and disposed of, while the resulting slurry is sent for further screening.
The raw feed material (ionic clays) is extracted from the deposit and either stockpiled or directly fed to the ore conditioning area for classification and washing into slurry form.
Classification and solid-liquid separation
The intermediate solution at the wet screen washes and concentrates the slurry, separating coarse (>1 mm) and fine (<1 mm) particles. Coarse particles undergo further cleaning and sorting, while fine particles are transferred to the counter-current decantation circuit. The process involves multiple stages of screening, washing, and thickening, using flocculants to aid solid settling. The intermediate solution is circulated back for reuse, and the slurry from the second thickener is directed to a filter holding tank, with further filtration to extract remaining REEs.
Ion exchange circuit
The slurry is fed into an ion exchange circuit for the extraction of valuable REEs through two stages of mixing and counter-current decantation reaction with a solvent solution. This generates a rich solution (containing REEs), an intermediate solution, and a “spent” slurry. The slurry is filtered to generate a low-moisture content product (barren material), a loaded solution (rich filtrate), and a washing solution (weak filtrate).
REE recovery and product handling
The processing sequence includes filtration of barren clay, generating strong and weak filtrates for recycling. The rich solution from Thickener 1 undergoes impurity removal in reactors, with the resultant clean solution used for REE precipitation. Impurities are filtered out, and the filtrate is recycled. The REE-rich solution is further processed to obtain a high-REE product, which is packaged for shipment.
Water recovery system
The liquid phases from the solid/liquid separation processes are treated in a water recovery system. This system recovers water and removes impurities, using chemical precipitation, nanofiltration, reverse osmosis, and ion exchange. It allows for a 95% reutilisation of the water contained within the process plant. The treated water is recirculated to generate a closed circuit to recover water and minimize the water supply needs of the process plant. Fresh water is sourced for various purposes, including reagent preparation and dust suppression.
Supporting systems
The process plant design includes scrubbers for treating off-gases. Clean gas is released to the atmosphere, while acid solution is recycled. Compressed air supports plant operations, with a constant supply ensured for various users, including filter presses and tube press filters. Potable and fire water systems serve different areas, with emergency showers and eyewash stations for safety.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Processed wet mineral feed rate (total) | 1,400 t/h | Design |
| Dry mineral feed rate | 1,204 t/h | Design |
| Fresh mineral moisture | 14.0% | Design |
| REE grade in feed | 1,071 ppm | Resource data (202 drillholes) |
| Average production rate (REO equivalent) | 4,498 t/year | Design (excludes ramp-up/down) |
| Dry carbonate product | 8,069 t/year | Design |
| REE2(CO3) grade in product | 91.7% | Design |
| Product purity (% REO equivalent) | 91.9% | Design |
| Ion exchange recovery (including cerium) | 35.0% | Testwork basis |
| Plant yield | 94.2% | Testwork basis |
| Overall performance (including cerium) | 33.0% | Testwork basis |
| Fresh water consumption | 117 m³/h | Design |
| Solid/liquid separation system efficiency | Validated through vendor tests | Vendor testwork |
Technical qualifications
This PEA update is based on a proposed process plant design. The total recovery rate of 33% is attributed to efficient REE precipitation, with the solid/liquid separation system efficiency validated through vendor tests as reported in Table 1-13 of the document. Process flow diagrams and plant layout figures are sourced from Promet101 (2024) and GE21 (2024). The report states that data from 202 drillholes inform the extraction plan and process facility design, determining ore flow, REE grades, and recoveries.
Source: *Carina Rare Earth Element Project , 2024 Preliminary Economic Assessment Update*, Aclara Resources Mineração Ltda., GE21 Project No. 240205, May 3, 2024, Sections 1.16 and 1.17.
