Optimizing Potash Recovery: Evaporation & Crystallization at Wynyard

Source: Karnalyte Resources Inc (2026)
Website: https://karnalyte.com/our-project/wynyard-carnallite-project/

Critical Data

Overview

Karnalyte Resources Inc. is advancing the Wynyard Project in Wynyard, Saskatchewan, a fully integrated potash and magnesium recovery operation based on a comprehensive 2025 NI 43-101 feasibility study. The facility is designed to produce 675,000 tonnes per annum (Phase 1) of high-grade potassium chloride (KCl) at 97% purity using solution mining brine as feed. The recovery methods leverage a proven multiple-effect evaporation (MEE) and draft tube baffle (DTB) crystallization circuit to selectively precipitate KCl and NaCl from the brine, achieving efficient separation and high product quality. The brine, sourced from underground caverns at approximately 50°C with a density of 1.265 g/cm³, contains 9.29% KCl and 9.86% MgCl₂. After removing insolubles and blanketing oil, the clean brine is evaporated in two trains of three-stage evaporators, followed by flash cooling to precipitate carnallite. KCl is further purified in a three-stage DTB crystallization train, dried in a rotary drum dryer, compacted into granular form, and stored for rail loadout. An integrated magnesium products plant processes the MgCl₂-rich end brine to produce 104,000 t/a of hydromagnesite at 99% purity via a carbonation and ammonia regeneration process. The combined potash and magnesium recovery methods maximize resource utilization, reduce waste, and deliver significant economic and environmental benefits. With annual operating hours of 8,000 for potash and 7,500 for magnesium, the Wynyard Project represents a modern, efficient solution for sustainable mineral production in Canada.

Key Process Stages

• Stage 1: Insolubles and Blanketing Fluid Removal – Feed brine is treated with flocculants in an inclined plate thickener to separate fine particulates and residual blanketing oil. Oil is recycled to the well field, and clean brine is stored in the evaporation feed tank.
• Stage 2: Evaporation and Carnallite Precipitation – Two trains of three-effect forced-circulation evaporators heat brine to precipitate NaCl and KCl crystals. Crystals settle in elutriation legs and are dewatered via 1,400 mm x 2,100 mm screen bowl centrifuges. Mother liquor is flash cooled in two stages to precipitate carnallite, which is converted in a DTB crystallizer to KCl and NaCl.
• Stage 3: Crystallization and KCl Purification – The KCl-rich overflow from the low-magnesium thickener is fed to a single train of three DTB crystallizers. The liquor cools from 99.0°C to 44.1°C under vacuum, producing KCl crystals. Water addition dissolves residual NaCl, and the KCl slurry is centrifuged to produce a 95% solid cake.
• Stage 4: Drying and Particulate Control – The KCl cake (95% solids) is dried in a 3.3 m diameter by 18 m long rotary drum dryer to 0.1% moisture. Natural gas burners provide heat. Vent gases pass through a cyclone and a three-section electrostatic precipitator to meet Saskatchewan emissions limits of 0.57 g/dry reference m³.
• Stage 5: Compaction and Product Handling – Dried fines are compacted into 14 mm sheets using two parallel compaction loops (120 t/h each). Sheets are broken, screened, and oversize crushed. On-size material is coated with a compaction additive, redried in a fluid bed dryer, and stored in a granular storage building before rail loadout.

Additional Interesting Data and Summary

The Wynyard Project’s recovery methods are supported by detailed equipment specifications and utility consumption data. The Phase 1 potash plant uses 0.32 MWh of electrical energy per tonne of finished product, supplied by Saskpower, and 15.5–16.5 GJ of natural gas per tonne for steam generation, dryer fuel, and building heating. Water consumption is approximately 18 m³ per finished tonne, used primarily for cavern development, process makeup, and NaCl dissolution. Reagents include flocculent for insoluble removal, lime for dryer exhaust neutralization, and compaction additives to improve granular hardness. The magnesium products plant, designed to treat 1,604 t/d of MgCl₂-rich brine (35% MgCl₂) from the potash process, produces 307 t/d of hydromagnesite at 99% purity via a six-step carbonation process. The process recycles ammonia with 98% efficiency using slaked lime from limestone calcination, minimizing makeup requirements (1.6 t/d). Environmental considerations include compliance with Saskatchewan air emission regulations (0.57 g/dry reference m³ for particulates) and deep-well disposal of waste brines into the Deadwood Formation. The combined potash and magnesium operations improve overall resource efficiency, converting a waste stream into a valuable product. Economic impact is significant: the Phase 1 capital cost for potash is estimated at CAD 1.4 billion, with magnesium facility costs additional. Future expansion to Phase 2 (1,425,000 t/a KCl) and Phase 3 (2,175,000 t/a) is planned, leveraging the same recovery methods. Opportunities exist to optimize ammonia capture further and reduce operational costs. Risks include variability in brine chemistry and potential scaling in evaporators, mitigated by robust design margins and continuous testing. The Wynyard Project positions Karnalyte Resources as a leading low-cost potash producer with a unique magnesium co-product, supporting sustainable mineral development in Saskatchewan.

Key Processes: Ball Mill, Crushing

Target Commodities: N/A