Abstract
This study investigates the direct extraction of nickel from a primary sulfide ore concentrate, predominantly pentlandite, using hydrochloric acid-loaded hydrophobic deep eutectic solvents (DES). The proposed system offers a solvometallurgical alternative to conventional processes by operating in a predominantly organic phase and reducing bulk aqueous waste streams. A hydrophobic DES composed of decanoic acid and methyltrialkylammonium chloride (mixture of C8-C10) was pre-loaded with hydrochloric acid and evaluated under moderate-temperature conditions. Nickel extraction reached up to 70% without the addition of external oxidants. The results emphasize the importance of effective acidity and chloride complexation within the organic medium in promoting metal dissolution from the sulfide matrix. Overall, the findings demonstrate the feasibility of hydrophobic DES systems as an alternative platform for sulfide ore processing in low-water solvent environments.