Date of Award
2026
Document Type
Campus Access Master's Thesis
Degree Name
Master of Science in Chemical Engineering (MS)
Administrative Home Department
Department of Chemical Engineering
Advisor 1
Lei Pan
Committee Member 1
Patrick Pinhero
Committee Member 2
Jeana Collins
Abstract
Critical minerals are essential components in energy and defense technologies, yet their supply chains are increasingly vulnerable to disruption. Pyrrhotite, an iron-rich sulfide mineral, is typically discarded to tailings due to its low concentration of valuable metals such as nickel (Ni), despite its high sulfur (S) and iron (Fe) content. This thesis presents a synergistic pressure oxidation leaching technology in which sulfide feed materials function simultaneously as in situ acid generators and reductive agents. This integrated approach eliminates the need for external reagents while enhancing process efficiency. The technology was successfully demonstrated for the extraction of critical minerals from two feedstocks: recycled cathode active materials (CAMs) derived from black mass and polymetallic manganese nodules. Under optimized hydrothermal conditions, high recoveries were achieved within 90 minutes, including Ni (98.3%), Co (100%), Mn (99.9%), Li (99.7%), and Cu (97.4%). Iron dissolution was effectively suppressed, with only 2.75% recovery, and was preferentially precipitated as hematite. Kinetic analysis using the shrinking core model revealed a mixed control mechanism involving both surface chemical reactions and product-layer diffusion, with activation energies of 27.9 kJ/mol (Ni), 25.3 kJ/mol (Mn), 31.97 kJ/mol (Co), and 29.09 kJ/mol (S). The process was further extended to polymetallic manganese nodules, achieving over 95% extraction of Mn, Ni, Cu, and Co at 175°C within 120 minutes, while maintaining iron co-precipitation below 4%. Kinetic modeling indicated that manganese dissolution was controlled by chemical reaction in both stages, whereas nickel extraction transitioned from chemical reaction control in the initial stage to mixed control in the later stage. Overall, this technology demonstrates a scalable and low-waste strategy for efficient recovery of critical minerals from both secondary and unconventional primary resources.
Recommended Citation
Buckman, Richmond, "HYDROMETALLURGICAL PRESSURE OXIDATION LEACHING OF CRITICAL MINERALS USING SULFIDE MINERALS", Campus Access Master's Thesis, Michigan Technological University, 2026.