Century Lithium’s Clayton Valley: DLE & Carbonate Recovery Process

Source: Century Lithium Corp (2026)
Website: https://www.centurylithium.com/news/2024/century-lithium-announces-positive-feasibility-study-for-the-clayton-valley-lithium-project-nevada

Critical Data

Overview

Century Lithium Corp. operates the Clayton Valley Lithium Project in Esmeralda County, Nevada, USA, a flat-lying clay-hosted lithium deposit at the Angel Island deposit. The feasibility study, effective January 3, 2026, details a comprehensive recovery methods flowsheet designed to produce high-purity lithium carbonate from fine-grained claystone. The process is significant for its innovative integration of attrition scrubbing for comminution, hydrochloric acid leaching, selective direct lithium extraction (DLE), and a chlor-alkali circuit that regenerates hydrochloric acid and sodium hydroxide for on-site reuse. This closed-loop approach minimizes chemical trucking and enhances sustainability. The plant initially processes 7,500 tonnes per day (t/d) in Phase 1, expanding to 15,000 t/d in Phase 2, achieving an overall lithium recovery of 84% from a feed grade averaging 0.113% Li. The flowsheet was developed and refined through pilot-scale operations at the Amargosa Valley Pilot Plant, validating key parameters such as leach extraction of 95% and DLE recovery of 98%. By combining attrition scrubbing, pH-controlled precipitation, ultrafiltration, and simulated moving bed DLE technology, Century Lithium demonstrates a technically viable and economically sound approach to unlocking the value of claystone lithium resources.

Key Process Stages

• Stage 1: Ore Receiving and Crushing – ROM claystone ore is trucked to a 30,000-ton covered stockpile. A 60-t feed hopper feeds a 24-in × 48-in double roll crusher, reducing ore to minus 4 inches. A variable-speed 4-ft × 25-ft McLanahan apron feeder and a stacker/reclaimer with 750 t/h capacity convey crushed ore to an attrition scrubber. Dust control via hood and baghouse ensures environmental compliance.
• Stage 2: Attrition Scrubbing – Crushed ore is mixed with high-pH process water at 33% solids in a 10-ft diameter × 30-ft long McLanahan horizontal attrition scrubber (350 hp). The scrubber breaks particles down to their interstitial size of 5–10 microns, liberating the clay crystalline structure. The slurry passes a 1-mm screen; oversize is conveyed to tailings while the undersize feeds the leach circuit.
• Stage 3: Leaching – The sized slurry enters two covered, rubber-lined leach tanks (10-m tall × 10-m diameter) with titanium agitators at 300 rpm. Leaching occurs at 70°C and pH -0.7 using 37% hydrochloric acid at ~4.8% of solids weight (96–110 kg HCl per tonne ore). Combined tank volume provides a 4-hour residence time. Lithium leach extraction reaches 90%, with overall extraction accounting for solution losses at 84%.
• Stage 4: Precipitation and Tailings Filtration – Leach slurry flows to a baffled precipitation tank (10-m × 10-m) where 50% sodium hydroxide raises pH to 7.5 for 2 hours, precipitating Al, Fe, and other deleterious elements as hydroxides. Air oxidizes ferrous to ferric iron. The slurry then feeds six plate-and-frame filters (215 plates each, 2.5-m × 2.5-m, membrane squeeze to 25 bar) achieving <30% cake moisture. The filtrate (direct lithium extractant, DLE) is polished through a 0.5-micron ultrafiltration unit.
• Stage 5: Direct Lithium Extraction and Elution – Clarified DLE solution (250–350 ppm Li, pH adjusted to 6.5) flows to a simulated moving bed DLE system from ARi using two parallel trains of seven columns (7–14-ft diameter × 9-ft high). Lithium adsorbs onto a proprietary aluminum hydroxide sorbent with 98% recovery. Stripping with reverse osmosis permeate produces an eluate of ~600 ppm Li, which is further concentrated to 4–6 g/L Li via a secondary RO unit. Raffinate is sent to Ca/Mg removal and then to the chlor-alkali circuit for chemical regeneration.

Additional Interesting Data and Summary

The Clayton Valley Lithium Project recovery system is underpinned by extensive pilot-scale testing and a robust process design basis. Key technical metrics include a leach temperature of 70°C with a 4-hour retention time, acid consumption of 6% by solution weight, and a lithium leach extraction of 95%. The DLE circuit achieves 98% lithium recovery while rejecting over 99% of Al, Fe, and Mg, and >95% of Ca, producing a high-grade eluate at 6.8 g/L Li after RO concentration. Lithium carbonate precipitation uses sodium carbonate at 1.1× stoichiometric ratio at 101°C, achieving 94% conversion rates. The chlor-alkali plant, designed with INEOS electrolyzers, produces 450 t/d of 32% sodium hydroxide and 400 t/d of chlorine (as 37% HCl), enabling closed-loop recycling of key reagents. Environmental considerations are integral: the tailings are non-acid producing (ABA testing confirmed), dry-stacked in a lined facility at pH 7.5, with the pit partially backfilled. Water recycling is emphasized; total make-up water is only 36.3 m³/h for Phase 1, minimizing freshwater demand. Sustainability initiatives include on-site chemical regeneration that reduces truck transport of HCl and NaOH, and the use of a hydrogen electrolyzer to manage by-product gases. Economically, the project produces 35.6 t/d of lithium carbonate in Phase 1 (71.2 t/d in Phase 2) at an average feed grade of 0.113% Li. The flowsheet is designed for modular expansion, with DLE and chlor-alkali units easily scalable. Future optimization is expected as the project advances, but the current feasibility study confirms technical viability. This integrated approach positions Century Lithium Corp. as a leader in sustainable claystone lithium processing, combining innovative DLE technology with chemical regeneration to achieve high recoveries with minimal environmental footprint. The plant’s 84% overall lithium recovery, low water consumption, and non-acid generating tailings underscore its potential as a benchmark for responsible lithium production in the Nevada basin.

Key Processes: Gravity Separation, Crushing

Target Commodities: Lithium