Overcoming the Iron Selectivity Hurdle in Nickel Bioleaching: A Critical Review of Mechanisms, Economic Challenges, and Future Research Directions

Document Type

Article

Publication Date

3-2-2026

Department

Department of Chemical Engineering

Abstract

The depletion of high-grade nickel sulfide ores has shifted global production toward low-grade laterites and mine tailings, which together account for approximately 70% of known nickel resources but remain difficult to process economically. Conventional pyrometallurgical and hydrometallurgical routes for these materials are constrained by high energy demand, intensive acid consumption, and increasing environmental costs. Bioleaching has emerged as a lower-intensity alternative operating at ambient temperature and pressure; however, its industrial deployment remains limited by excessive iron co-dissolution, which contaminates the pregnant leach solution (PLS) and undermines downstream economic viability. This review evaluates nickel bioleaching through the lens of iron selectivity rather than nickel extraction alone. It shows that nickel liberation from laterites is intrinsically coupled to iron dissolution due to the structural association of Ni within ferric iron minerals. Although many studies report nickel recoveries of 30–85%, they frequently generate PLS with Fe/Ni mass ratios exceeding 10:1, imposing substantial purification penalties. Reductive bioleaching using dissimilatory iron-reducing bacteria is mechanistically aligned with lateritic mineralogy, yet most reported systems rely on costly organic substrates and lack integrated iron management. Four critical gaps must be addressed to enable industrially viable nickel bioleaching: in-situ iron immobilization, replacement of purchased reagents with waste-derived biomass, engineering of synergistic microbial consortia, and pilot-scale validation supported by techno-economic analysis. Addressing these gaps is essential to transition nickel bioleaching from laboratory feasibility to a competitive, low-carbon processing route.

Publication Title

Mineral Processing and Extractive Metallurgy Review

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