Recycling of waste pickle acid by precipitation of metal fluoride hydrates

Kerstin M. Forsberg; Åke C. Rasmuson

doi:10.1016/j.mineng.2007.03.011

Recycling of waste pickle acid by precipitation of metal fluoride hydrates

Kerstin M. Forsberg, Åke C. Rasmuson

KTH Royal Institute of Technology

Research output: Contribution to journal › Article › peer-review

Abstract

Stainless steel is pickled in mixed acid solutions (1-3 M HNO₃ and 0.5-4 M HF). The spent solution is usually neutralized with lime, and in Sweden about 18,000 tons/yr of metal hydroxide sludge is disposed as landfill waste. We are developing a cost-saving and environmentally friendly process, involving crystallization of β-FeF₃ · 3H₂O, where the metal content is recovered and the acid is recycled. Iron has been successfully separated from spent pickle bath solutions by precipitation of β-FeF₃ · 3H₂O in a continuous crystallizer (10 L scale) where the solution is concentrated by nanofiltration. The crystal growth rate of β-FeF₃ · 3H₂O has been determined in industrial pickle bath solutions at 50 °C and the results have been compared to previous measurements in pure HF/HNO₃ solutions prepared in the laboratory. The growth rate of β-FeF₃ · 3H₂O crystals at 50 °C is in the order of 10^-11 m/s in both industrial and pure acid mixtures.

Original language	English
Pages (from-to)	950-955
Number of pages	6
Journal	Minerals Engineering
Volume	20
Issue number	9 SPEC. ISS.
DOIs	https://doi.org/10.1016/j.mineng.2007.03.011
Publication status	Published - Aug 2007
Externally published	Yes

Keywords

Hydrometallurgy
Recycling
Waste processing

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.mineng.2007.03.011

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title = "Recycling of waste pickle acid by precipitation of metal fluoride hydrates",

abstract = "Stainless steel is pickled in mixed acid solutions (1-3 M HNO3 and 0.5-4 M HF). The spent solution is usually neutralized with lime, and in Sweden about 18,000 tons/yr of metal hydroxide sludge is disposed as landfill waste. We are developing a cost-saving and environmentally friendly process, involving crystallization of β-FeF3 · 3H2O, where the metal content is recovered and the acid is recycled. Iron has been successfully separated from spent pickle bath solutions by precipitation of β-FeF3 · 3H2O in a continuous crystallizer (10 L scale) where the solution is concentrated by nanofiltration. The crystal growth rate of β-FeF3 · 3H2O has been determined in industrial pickle bath solutions at 50 °C and the results have been compared to previous measurements in pure HF/HNO3 solutions prepared in the laboratory. The growth rate of β-FeF3 · 3H2O crystals at 50 °C is in the order of 10-11 m/s in both industrial and pure acid mixtures.",

keywords = "Hydrometallurgy, Recycling, Waste processing",

author = "Forsberg, {Kerstin M.} and Rasmuson, {{\AA}ke C.}",

year = "2007",

month = aug,

doi = "10.1016/j.mineng.2007.03.011",

language = "English",

volume = "20",

pages = "950--955",

journal = "Minerals Engineering",

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TY - JOUR

T1 - Recycling of waste pickle acid by precipitation of metal fluoride hydrates

AU - Forsberg, Kerstin M.

AU - Rasmuson, Åke C.

PY - 2007/8

Y1 - 2007/8

N2 - Stainless steel is pickled in mixed acid solutions (1-3 M HNO3 and 0.5-4 M HF). The spent solution is usually neutralized with lime, and in Sweden about 18,000 tons/yr of metal hydroxide sludge is disposed as landfill waste. We are developing a cost-saving and environmentally friendly process, involving crystallization of β-FeF3 · 3H2O, where the metal content is recovered and the acid is recycled. Iron has been successfully separated from spent pickle bath solutions by precipitation of β-FeF3 · 3H2O in a continuous crystallizer (10 L scale) where the solution is concentrated by nanofiltration. The crystal growth rate of β-FeF3 · 3H2O has been determined in industrial pickle bath solutions at 50 °C and the results have been compared to previous measurements in pure HF/HNO3 solutions prepared in the laboratory. The growth rate of β-FeF3 · 3H2O crystals at 50 °C is in the order of 10-11 m/s in both industrial and pure acid mixtures.

AB - Stainless steel is pickled in mixed acid solutions (1-3 M HNO3 and 0.5-4 M HF). The spent solution is usually neutralized with lime, and in Sweden about 18,000 tons/yr of metal hydroxide sludge is disposed as landfill waste. We are developing a cost-saving and environmentally friendly process, involving crystallization of β-FeF3 · 3H2O, where the metal content is recovered and the acid is recycled. Iron has been successfully separated from spent pickle bath solutions by precipitation of β-FeF3 · 3H2O in a continuous crystallizer (10 L scale) where the solution is concentrated by nanofiltration. The crystal growth rate of β-FeF3 · 3H2O has been determined in industrial pickle bath solutions at 50 °C and the results have been compared to previous measurements in pure HF/HNO3 solutions prepared in the laboratory. The growth rate of β-FeF3 · 3H2O crystals at 50 °C is in the order of 10-11 m/s in both industrial and pure acid mixtures.

KW - Hydrometallurgy

KW - Recycling

KW - Waste processing

UR - http://www.scopus.com/inward/record.url?scp=34447256127&partnerID=8YFLogxK

U2 - 10.1016/j.mineng.2007.03.011

DO - 10.1016/j.mineng.2007.03.011

M3 - Article

AN - SCOPUS:34447256127

SN - 0892-6875

VL - 20

SP - 950

EP - 955

JO - Minerals Engineering

JF - Minerals Engineering

IS - 9 SPEC. ISS.

ER -

Recycling of waste pickle acid by precipitation of metal fluoride hydrates

Abstract

Keywords

UN SDGs

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