The February 2024 preliminary economic assessment for Hub City Lithium's Viewfield project in southern Saskatchewan treats Duperow formation brine with sorption columns, reverse osmosis, ion exchange and a single-step carbonation reactor, with 90% estimated DLE recovery.
The Viewfield Lithium Brine Project lies in the Viewfield area of southern Saskatchewan, Canada. The NI 43-101 Technical Report Preliminary Economic Assessment of the Lithium Brines in Viewfield Area Phase 1 was commissioned by Hub City Lithium Corp. (HCL), a privately held lithium company, and prepared for EMP Metals Corp., ROK Resources Inc. and Hub City Lithium. Sproule Associates, Red Tree Exploration, Saltworks Technologies and Koch Technology Solutions prepared it, with a report date of February 12, 2024 and an effective date of October 31, 2023. Phase 1 is estimated to produce an average of about 12,175 t/y of lithium carbonate equivalent (LCE) from the Duperow formation for use in lithium-ion batteries. The processes include advanced sorption technology for direct lithium extraction (DLE), and membrane filtration, ion exchange and reactors for the downstream concentration, refining and conversion (CRC) process.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Phase 1 production | About 12,175 | t/y LCE | Average |
| Preliminary design maximum | 20,000 | t/y LCE | DLE basis |
| Feed brine flow | 2,583 | m3/h | 62,000 m3/day |
| Feed brine lithium | 200 | mg/L | Not applicable |
| DLE recovery | 90 | % | Estimated |
| Contaminant polish target | Below 5 | mg/L | Ion exchange before carbonation |
| Carbonation reagent | Na2CO3 | Not applicable | Single-step crystallization |
| Concentration steps | 2 | steps | Reverse osmosis, then OARO |
| Base case concentrator | MVR | Not applicable | Conservative assumption |
| Pilot partners | 3 | companies | ESM, Koch, Saltworks |
Overview
Produced brine is pre-filtered and passed to a DLE sorption process that makes a lithium chloride eluate. Spent brine returns to the reservoir by disposal wells. The eluate is concentrated by reverse osmosis and an osmotically assisted reverse osmosis (OARO) membrane step, softened by chemical precipitation, polished on ion exchange and converted to lithium carbonate by sodium carbonate. HCL has engaged key technology contributors, though no long-term contractual obligations have been executed. A pilot with Energy Source Minerals (ESM) succeeded, and a Koch treatability study is under way, with a field pilot using Koch equipment planned for 2024.
Key Process Stages
Brine pre-filtration
Produced brine may need pre-treatment to remove contaminants such as iron and silica. Other North American projects face oil and hydrogen sulphide, but the Viewfield brine does not contain them, as various compositional analyses confirmed. Ultrafiltration with PVDF or ceramic membranes can handle pre-filtration to meet DLE system needs.
Direct lithium extraction
Feed brine is adsorbed onto the vendor's proprietary sorption process. The lithium is stripped from the loaded sorbent with water. It is a batch process, so several columns run cyclically in parallel, some in exchange and others in regeneration. The lithium-depleted brine is returned to the wellfield for re-injection into the reservoir or disposed into another aquifer, and the plant pipes barren brine underground to multiple deep disposal wells across the project area.
Concentration
The lithium chloride eluate is concentrated in two steps. Conventional reverse osmosis pre-concentrates it, and OARO, built from off-the-shelf RO components, takes it to target concentration. If OARO falls short, an evaporator can finish the job at higher capital cost and energy use. The mass balance and cost estimates assume a mechanical vapor recompression (MVR) thermal step after reverse osmosis, which the report calls a conservative economic assumption, since OARO was successfully pilot tested and removes the need for MVR. Permeate and evaporator condensate are recycled to the DLE step to minimize external water use.
Chemical precipitation and polishing
Calcium, magnesium, silica and boron affect product purity and can scale equipment. Chemical softening removes the bulk of them, before or after membrane concentration depending on eluate chemistry. A final ion exchange polish brings contaminant levels below 5 mg/L immediately before carbonation.
Carbonation, washing and packaging
Purified, concentrated lithium chloride is converted to lithium carbonate by a concentrated sodium carbonate solution in one crystallization step. Solids are separated from the mother liquor and washed in multiple stages to remove entrained liquor, which would hurt purity. The product is then dried and packaged for transport.
Additional Interesting Data and Summary
The report lists benefits of the selected processes: higher lithium recovery, higher purity, shorter processing time, lower capital and operating cost, a simplified flowsheet, a smaller footprint, fewer chemicals and lower process water needs. Refining and conversion pilot testing with Saltworks has been completed and produced battery grade lithium carbonate.
The preliminary design is for a maximum output of 20,000 t/y of LCE, against the Phase 1 average of about 12,175 t/y. The brine is handled in closed circuit, with water recycled from the RO and evaporator, and the report says savings would result if OARO replaced the thermal step.
Hub City Lithium is owned 75% by EMP Metals and 25% by ROK Resources. Phase 1 covers about 11,000 ha, or 45% of its Viewfield holdings, with more than 692,000 t of LCE in place in a 42.75 sub-section block. The wellfield plan is 36 horizontal, multi-leg production wells of 1 to 2 miles, spaced at about one per section, feeding five centralized DLE sites through underground pipelines. Each DLE site runs at 12,400 m3/d. Concentrated lithium chloride then moves by pipeline to one of two refining sites, where it is further concentrated, converted to battery grade carbonate and packaged. Depleted brine goes to 30 disposal wells targeting the Mannville, Alida or Tilston formations.
Stage 1 produces the commingled Wymark C, D and E zones at an average 184 mg/L, with about 18,600 t/y of carbonate over roughly seven years from 2027. Stage 2 targets the deeper Wymark A and B and Saskatoon A and B members at about 100 mg/L, adding about 10,000 t/y over a 16-year project life as Stage 1 volumes deplete.
Key Processes
- Ultrafiltration pre-treatment
- Direct lithium extraction by selective sorption
- Reverse osmosis and OARO membrane concentration
- Chemical softening and ion exchange polishing
- Single-step sodium carbonate crystallization
- Product washing, drying and packaging
- Deep well disposal of barren brine
Source: NI 43-101 Technical Report Preliminary Economic Assessment of the Lithium Brines in the Viewfield Area, Phase 1, Southern Saskatchewan, Canada, February 12, 2024.
