In situ arsenic immobilization via oxidative co-precipitation and integrated P204-based impurity removal coupled with crystallization for the production of battery-grade NiSO4·6H2O--颗粒学报PARTICUOLOGY

In situ arsenic immobilization via oxidative co-precipitation and integrated P204-based impurity removal coupled with crystallization for the production of battery-grade NiSO₄·6H₂O

Yaoyu Yan^{a b c}, Shuchen Sun^{a b c *}, Jing Wei^{a b c}, A. Shubo^{a b c}, Faxin Xiao^{a b c}, Ganfeng Tu ^{a b c}

a School of Metallurgy, Northeastern University, Shenyang, 110819, China
b Key Laboratory for Recycling of Nonferrous Metal Resources (Shenyang), Shenyang, 110819, China
c Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang, 110819, China

10.1016/j.partic.2026.02.022

Volume 112, May 2026, Pages 11-23

Received 6 January 2026, Revised 31 January 2026, Accepted 14 February 2026, Available online 6 March 2026, Version of Record 13 March 2026.

E-mail: sunsc@smm.neu.edu.cn

Highlights

• A compact purification-crystallization route upgrades crude NiSO₄ liquors to battery-grade NiSO₄·6H₂O.

• Iron-assisted oxidative pretreatment achieved efficient arsenic fixation via Fe–As co-precipitation with low Ni loss.

• Condensed solvent extraction and organic-phase recycling to fit the character limit without losing the technical specifics.

• Changed phase-pure to pure and slightly streamlined the verification methods to ensure it fit comfortably under limit.

Abstract

Targeting the high arsenic risk and complex impurity matrix of crude nickel sulfate liquor generated as a by-product from electrolytic copper de-nickelization, this study validates a short, crystallization-compatible purification route integrating oxidative arsenic co-precipitation, single-extractant P204 (D2EHPA) solvent extraction, and evaporative crystallization. Endogenous iron served as an arsenic-scavenging carrier; under 1.3 × theoretical H₂O₂, endpoint pH 4–5, and 50 °C, As and Fe removals reached 99.7% and 98.9%, respectively, with an apparent Ni loss of 3–10%. Under the optimized extraction window (25 vol% P204, equilibrium pH 4.0–4.5, O/A = 2.0, 50–60% saponification, 8–10 min), Zn and Cu were reduced from 2.15 to 0.16 g L⁻¹ to 0.092 and 0.006 g L⁻¹ (>95% removal) while keeping Ni co-extraction below 5%; scrubbing/stripping (0.15/1.0 mol L⁻¹ H₂SO₄) enabled organic-phase regeneration. After deoiling, crystallization produced NiSO₄·6H₂O, confirmed by XRD and SEM–EDS. The product contained 22.15 wt% Ni (specification ≥22.08 wt%) with Cu 0.00005 wt%, Zn 0.00028 wt%, and Fe 0.00042 wt%, all below the battery-grade limits (HG/T 5919—2021). Overall, this work demonstrates a crystallization-compatible route using endogenous-iron-assisted arsenic immobilization/removal via oxidative co-precipitation and a single P204 loop for Zn/Cu removal with suppressed Ni co-extraction, enabling battery-grade NiSO₄·6H₂O within defined operating windows.

Graphical abstract

Keywords

Crude nickel sulfate; Arsenic immobilization; P204 (D2EHPA); Solvent extraction; Battery-grade NiSO₄·6H₂O

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