Abstract
The increasing global demand for nickel, driven by advanced energy infrastructure, electric vehicle batteries, and stainless-steel production, has intensified the need for efficient and sustainable extraction technologies as high-grade resources become depleted. In Canada, nickel sulfide ores, particularly pentlandite, remain a critical source of Class I nickel; however, conventional pyrometallurgical processing is becoming energy-intensive and emits significant greenhouse gases. This work examined hydrometallurgical processing routes for nickel recovery from nickel sulfide resources, with a focus on simultaneously atmospheric leaching systems and direct CO2 sequestration from air by utilizing organic complexing agents. The performance of nitrilotriacetic salt (NTA) in the synergistic leaching system was evaluated and compared with alternative ligands, such as glycine and glutamate diacetate (GLDA) salts, in terms of nickel recovery, selectivity, and impurity control. In addition, the potential integration of mineral carbonation within the hydrometallurgical process was explored as a pathway for simultaneous nickel recovery and carbon dioxide sequestration. The test results have shown that appropriate control of leaching conditions can enable effective metal extraction while promoting CO₂ mineralization without adversely affecting nickel recovery. This integrated approach demonstrates strong potential to reduce the environmental footprint of nickel processing and supports the development of low-carbon, sustainable nickel production strategies aligned with Canada’s critical minerals objectives and the global clean energy transition.