La Loutre Graphite Project: Flotation Recovery Process & Design

Source: Lomiko Metals Inc (2026)
Website: https://lomiko.com/projects/la-loutre/

Critical Data

Overview

Lomiko Metals Inc. operates the La Loutre Graphite Project, a pre-feasibility stage development in Quebec, Canada. The mineral processing plant is designed to treat 1.7 million tonnes per year of ore using a conventional flotation-based recovery method that maximizes graphite flake size and concentrate purity. The flowsheet integrates crushing, semi-autogenous grinding (SAG), flash flotation, multi-stage cleaner flotation, and polishing steps to achieve a blended graphite concentrate grade of 97.0% graphitic carbon (Cg) with an overall recovery of 93%. The plant will produce three size fractions — coarse (+80 mesh), intermediate (-80+200 mesh), and fine (-200 mesh) — totaling 79,601 dry tonnes per year. Designed to operate 24 hours per day, the concentrator achieves 92% effective utilization, while the crushing circuit runs at 66.7% utilization. The recovery process was developed from extensive metallurgical test programs and is tailored to minimize flake degradation. Key reagents include diesel as a collector and methyl isobutyl carbinol (MIBC) as a frother. Tailings are thickened, filtered, and dry-stacked to reduce environmental impact, with a desulphurization circuit planned to produce non-acid generating tailings. The project benefits from Canadian government support, with NRCan contributing $4.9 million (75% of project cost) for graphite anode piloting, expected to finalize in early 2027.

Key Process Stages

• Stage 1: Crushing and Stockpiling – Run-of-mine ore passes a static grizzly and vibrating grizzly screen (90 mm spacing). Oversize material is crushed by a 1,300 mm × 1,000 mm jaw crusher to a P80 of 105 mm. Tramp steel is removed via a self-cleaning permanent magnet before the ore is conveyed to a covered dome stockpile. Two apron feeders reclaim crushed material for the grinding circuit.
• Stage 2: Grinding and Classification – The SAG mill (7.3 m Ø × 3.1 m EGL, 2,600 kW) operates in closed circuit with a double-deck vibrating screen (8 mm top deck, 3 mm bottom deck). Screen undersize feeds the rougher flotation cell, while oversize is recirculated to the SAG mill. A hydrocyclone cluster further classifies material, with underflow returning to the SAG mill for additional grinding.
• Stage 3: Rougher and Scavenger Flotation – Flash flotation in a single 85 m³ cell recovers coarse graphite flakes before overgrinding. Rougher concentrate is sent to polishing. Rougher tails are classified, with cyclone overflow feeding a scavenger bank of four 20 m³ conventional flotation cells. Combined rougher and scavenger concentrate reaches ~25.7% Cg. Scavenger tails report to the tailings thickener.
• Stage 4: Polishing and Multi-Stage Cleaner Flotation – The combined concentrate passes through two polishing mills (6.1 m Ø and 4.3 m Ø, using ceramic media) to liberate gangue without reducing flake size. Four cleaner flotation stages (5 m³ cells) operate in series, with tailings recycled to the previous stage. Fourth cleaner concentrate achieves ~93.0% Cg and is screened at 80 mesh (177 µm) into coarse and fine streams, each undergoing dedicated stirred media milling and additional cleaner flotation stages (coarse: two stages; fine: three stages) to reach final concentrate grades of 96.6% Cg and 97.2% Cg, respectively.
• Stage 5: Concentrate Dewatering, Drying, and Packaging – The combined coarse and fine concentrates are filtered in a vertical plate pressure filter, producing a cake at 15% moisture. An indirect rotary natural gas dryer reduces moisture to 0.3%. Dried concentrate is pneumatically conveyed to a sifting system that yields three size fractions. Each fraction is stored in dedicated bins and packaged into 1.0 t bags, which are palletized and stretch-wrapped for shipment.

Additional Interesting Data and Summary

The La Loutre Graphite Project’s processing plant is designed with robust equipment to deliver high-grade graphite concentrate. The major mechanical equipment includes a single SAG mill (2,600 kW), two polishing mills (1,200 kW and 630 kW), multiple flotation cells totalling over 500 m³ of installed capacity, and two stirred media mills (90 kW each) for coarse and fine streams. The total installed power is 12.5 MW. Reagent consumption is low: less than 1 t/d each for diesel (collector) and MIBC (frother). Flocculant is used for tailings thickening. Water management emphasizes recycling, with make-up water of 514 m³/d sourced from pit dewatering and polishing ponds, and only 45 m³/d of additional process water make-up. The tailings dewatering circuit includes a 21 m diameter high-capacity thickener and a vertical plate filter press, producing a filter cake at 12% moisture for dry stacking. This reduces the environmental footprint and supports the project’s sustainability goals. The concentrator mass balance shows 4,750 dry t/d solids entering, with 318 t/d of final concentrate and 4,432 t/d of dry-stacked tailings. The concentrate is divided into three fractions: 24.0% coarse (+80 mesh), 45.1% intermediate (-80+200 mesh), and 30.8% fine (-200 mesh), enabling flexible market supply for lithium-ion battery anodes and other industrial applications. The project has strong economic significance, producing 79,601 tpy of 97.0% Cg concentrate at 93% recovery from a 4.79% feed grade. Environmental considerations include a low-sulfur tailings product through desulphurization, and the use of dry stack tailings storage eliminates the need for conventional tailings ponds. The future outlook is positive: with NRCan funding of $4.9 million, graphite anode piloting is ongoing and expected to finalize in early 2027, further validating the product for battery markets. This pre-feasibility study, based on metallurgical test work and flowsheet development, positions La Loutre as a significant potential supplier of high-purity, large-flake graphite concentrate for the growing electric vehicle and energy storage sectors.

Key Processes: Flotation, Gravity Separation, SAG Mill, Crushing

Target Commodities: N/A