Selective Separation and Recovery of Ni,  Cu and Cr from Electroplating Sludge via Hydrometallurgical Processes

Suhyeon Lee; In-Hyeok Choi; Bon Woo Gu; Hong Il So; Byeongwoo Kim; Hwansu Lee; Om Shankar Dinkar; Kyoungkeun Yoo

doi:10.7844/kirr.2026.35.4.56

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2026 Vol.35, Issue 4 Preview Page Next Page

Selective Separation and Recovery of Ni, Cu and Cr from Electroplating Sludge via Hydrometallurgical Processes 전기도금 슬러지로부터 습식제련공정에 의한 니켈·구리·크롬의 선택적 분리 및 회수

31 August 2026. pp. 56-65

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Abstract

To produce high-purity nickel sulfate from nickel-bearing sludge generated in electroplating processes, this study evaluated a three-step hydrometallurgical pretreatment and purification process comprising sulfuric acid leaching, cementation, and neutralization–precipitation. In the leaching step, the application of 1–2 M H₂SO₄ at a 25 w/v% solids content achieved near-quantitative dissolution (≥ 99%) of Ni, Cu, and Cr within 15 min, with a low leaching efficiency of 0.5 M. Filtration performance improved markedly at a 1.2 M acid concentration. Complete metal dissolution was confirmed at 10–25 w/v% solids contents, and at ≥ 50 w/v%, slurry viscosity increased, leading to reduced agitation efficiency and suppressed leaching. To remove Cu from the leachate, reducing agents (metallic Fe, FeO, and FeSO₄·7H₂O) were compared and metallic Fe powder identified as the most selective and effective reductant. Under conditions of Fe/Cu = 150 wt% at 80 °C for 90 min, residual Cu was reduced to ≤ 1 mg/L and Ni loss was suppressed to approximately 3%. When the reaction time exceeded 90 min, Ni precipitation was observed. To remove Cr in the neutralization–precipitation step, neutralizing agents (NaOH and CaCO₃) were compared, with CaCO₃ outperforming NaOH owing to its buffering effect, which induced a gradual pH increase, thereby selectively removing Cr while significantly suppressing Ni co-precipitation. By applying CaCO₃ at pH 4 and 50 °C for 180 min, a chromium recovery of ≥ 99% was achieved with Ni loss below 1%.

Keywords

Electroplating sludge

Hydrometallurgical process

Leaching

Cementation

Neutralization precipitation

본 연구에서는 도금 공정에서 발생하는 니켈 함유 슬러지로부터 고순도 황산니켈 제조를 위한 전처리·정제 공정으로 황산 침출-세멘테이션-중화침전의 3단계 공정을 평가하였다. 황산 침출 단계에서는 고액비 25 w/v% 조건에서 황산 1-2 M을 적용할 경우 Ni, Cu, Cr이 15분 이내에 99% 이상 신속히 용출된 반면, 0.5 M에서는 용출률이 낮았다. 여과성은 황산 1.2 M 이상에서 유의하게 개선되었으며, 고액비 10-25 w/v% 범위에서 완전 용해가 확인된 반면, 50 w/v% 이상에서는 슬러리 점도 상승에 따른 교반 효율 저하 및 침출율 감소가 관찰되었다. 침출액 내 Cu 제거를 위한 세멘테이션 공정에서는 환원제 종류 비교(Fe, FeO, FeSO₄·7H₂O) 결과 금속 Fe 분말이 가장 선택적이고 효과적인 환원제로 확인되었다. Fe/Cu 투입량 150 wt%, 80 ℃, 90 min 조건에서 잔류 Cu를 1 mg/L 이하로 저감하면서 Ni 손실을 약 3% 수준으로 억제할 수 있었으며, 반응시간 90분 초과 시 Ni 침전이 관찰되었다. Cr 제거를 위한 중화침전 공정에서는 중화제(NaOH, CaCO₃)를 비교한 결과, CaCO₃가 완충작용을 통해 pH 상승을 완만하게 유도함으로써 NaOH 대비 Ni 공침을 현저히 억제하면서 Cr을 선택적으로 제거하는 데 우수한 성능을 보였다. CaCO₃를 중화제로 적용하여 pH 4, 50 ℃, 180 분 조건에서 크롬 회수율 99% 이상, Ni 손실 1% 미만을 달성하였다.

키워드

도금 슬러지

습식제련

침출

세멘테이션

중화침전

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Information

Publisher :The Korean Institute of Resources Recycling
Publisher(Ko) :한국자원리싸이클링학회
Journal Title :Resources Recycling
Journal Title(Ko) :자원리싸이클링
Volume : 35
No :4
Pages :56-65
Received Date : 2026-05-04
Revised Date : 2026-06-18; 2026-07-16
Accepted Date : 2026-07-24
DOI :https://doi.org/10.7844/kirr.2026.35.4.56

Resources Recycling ISSN:2765-3439(Print) 2765-3447(Online) 자원리싸이클링

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