Passivation-free and carbon-negative extraction of nickel and cobalt from olivine using pressurized attrition-assisted carbonation leaching technology

Document Type

Article

Publication Date

2-1-2026

Abstract

Extraction of nickel (Ni) and cobalt (Co) from nickel-bearing olivine silicate minerals using hydrothermal carbonation leaching is often limited by the formation of silica-rich passivating layers. This study introduces an attrition-assisted hydrothermal carbonation leaching process that selectively extracts Ni and Co from olivine feedstocks using disodium ethylenediaminetetraacetate (EDTA) as a chelating ligand while simultaneously precipitating iron and magnesium as carbonate minerals using carbon dioxide, without forming passivating layers. By integrating direct mechanical attrition with carbonation reaction, the pressurized attrition system achieves rapid kinetics, attaining up to 64% Ni extraction and 60% carbonation efficiency within 2 h. The process is more effective for coarser feedstocks (D80 = 147 μm) than for finer feedstocks (D80 = 20 μm), highlighting the critical role of continuous exposure of fresh surfaces in promoting the dissolution of divalent ions from feedstocks. Microscopic analysis confirmed the continuous exfoliation of magnesite products and amorphous silica layers under pressurized attrition, in contrast to the diffusion-limiting films observed in conventional agitated systems. Techno-economic analysis indicates a 3.5-fold increase in profitability and a 40% reduction in operating costs relative to conventional agitated systems, enabled by improved Ni yield revenues and higher carbon credits. The present work demonstrates the strong potential of pressurized attrition during the carbonation leaching to enable simultaneous critical mineral extraction and CO2 sequestration.

Publication Title

Chemical Engineering Journal

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