Thor Project Alumina Recovery: HCl Leaching & Crystallization

Source: Canadian Energy Metals Corp (2026)
Website: https://canadianenergymetals.com/thor-project

Critical Data

Overview

Canadian Energy Metals Corp is advancing the Thor Property, a black shale deposit located near Tisdale, Saskatchewan, Canada, with a comprehensive Preliminary Economic Assessment (PEA) detailing a robust alumina recovery flowsheet. The candidate flowsheet, developed from bench-scale testing and presented in Section 17 of the technical report, targets the production of custom Chemical Grade Alumina (CGA) at 99.9% purity and High Purity Alumina (HPA) at 99.99% purity from an aluminous black shale feed grading 13.4% Al2O3. The process begins with comminution via roll sizers and a vertical roller mill to achieve a P80 of 1,000 µm, followed by atmospheric hydrochloric acid leaching to solubilize aluminum and other metals. The pregnant leach solution undergoes selective crystallization steps—including a proprietary pre-crystallizer impurity removal system for HPA production—where HCl-rich vapour sparging precipitates aluminum as Aluminum Chloride Hexahydrate (ACH). Subsequent pyrometallurgical conversion yields the final alumina products. The overall process recovery is estimated at 81.1%, with an annual production capacity of 1.78 million tonnes of Al2O3 equivalent. This flowsheet emphasizes acid and water recycling, with a make-up HCl stream, and includes residue neutralization using quicklime to manage acid-generating potential. The Thor Project represents a significant opportunity for sustainable alumina production in Canada, leveraging innovative hydrometallurgical and pyrometallurgical technologies.

Key Process Stages

• Stage 1: Comminution (Crushing and Grinding) – Run of mine feed is passed through a grizzly and roll sizer circuit to achieve a P80 of approximately 75 mm. Crushed material is stored in a dome stockpile, reclaimed, and fed to a Vertical Roller Mill (VRM) with an integrated classifier to produce a ground product with a P80 of approximately 1,000 µm. Future testwork will optimize grind size for metal extraction.
• Stage 2: Hydrochloric Acid Leaching – Ground feed is mixed with recycled HCl solution in a series of agitated atmospheric tanks. Aluminum and other metals are solubilized, forming aqueous chlorides. Calcite reacts to produce CaCl2 and CO2. The leach slurry is filtered using horizontal belt filters to separate Pregnant Leach Solution (PLS) from washed leach residue.
• Stage 3: Residue Neutralization – Washed leach residue is repulped with a lime-bearing solution in an agitated tank to neutralize residual acid. The slurry is filtered again, with liquid recycled to a lime slaker (using quicklime, CaO) to generate Ca(OH)2 for the neutralization step. The neutralized filter cake, classified as potentially acid generating, is sent to a residue storage system.
• Stage 4: Crystallization and Impurity Removal – A portion of PLS undergoes proprietary pre-crystallizer impurity removal before high-purity crystallization. Both high-purity and PLS crystallization steps sparge recycled HCl-rich vapour into agitated tanks to increase acidity and selectively precipitate aluminum as Aluminum Chloride Hexahydrate (ACH). The exothermic reaction requires heat removal via recirculation pumps and exchangers. ACH crystals are separated by belt filtration.
• Stage 5: Pyrometallurgical Conversion to Alumina – ACH from high-purity crystallization is calcined via proprietary methods to produce High Purity Alumina (HPA, 99.99% Al2O3), while ACH from PLS crystallization is converted to Chemical Grade Alumina (CGA, 99.9% Al2O3). Products are ground, bagged, and stored. HCl is recovered from ACH and chlorinated impurities using proprietary methods.

Additional Interesting Data and Summary

The Thor Project’s alumina recovery flowsheet integrates advanced hydrometallurgical and pyrometallurgical processes designed for high efficiency and environmental stewardship. Key technical parameters include a feed tonnage of 16.4 Mt/year (dry) at 13.4% Al2O3, yielding 1.4 Mt/year of CGA and 0.35 Mt/year of HPA, with a byproduct stream of 2.21 Mt/year of other oxides. The simplified mass balance indicates substantial reagent consumption: 0.02 Mt/year HCl makeup, 0.59 Mt/year CaO for neutralization, and 0.47 Mt/year NaOH for scrubbing. Energy demands are dominated by the HCl recovery system (71.3 million GJ/year), steam generation (57.7 million GJ/year), and CGA calcination (43.2 million GJ/year). The process plant’s total electrical load is 108 MW. Environmental considerations are central to the design. Leach residue is classified as potentially acid generating based on acid-base accounting testwork, requiring a dedicated residue treatment and storage system to mitigate acid mine drainage. Blowdown from boilers and cooling towers generates liquid effluent, which is addressed in the report’s environmental sections. The facility will source fresh process water, demineralized water from internal systems, and potable water from Tisdale municipal supply. Natural gas is the primary fuel, with biomass under investigation as a sustainable alternative. Economically, the project aims to produce custom CGA and HPA meeting industry specifications (99.9% and 99.99% Al2O3 purity, respectively) in alpha-alumina crystal form. The high level of acid and water recycling reduces operating costs and environmental impact. Future testwork will refine grind size optimization (currently targeting P80 1,000 μm with assumed kinetics similar to P88 595 μm) and evaluate the metallurgical response of the Lea Park formation, which will be mined according to the mine plan. The Thor Property, located in Saskatchewan, positions Canadian Energy Metals Corp as a potential leader in domestic alumina production, leveraging innovative proprietary technologies for impurity removal, crystallization, and HCl recovery. Ongoing studies will further characterize mineralogy, energy integration, and byproduct valorization to enhance project economics and sustainability.

Key Processes: Crushing

Target Commodities: N/A