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Pilot-scale counter-current acid leaching process for Cu, Pb, Sb, and Zn from small-arms shooting range soil.

Guemiza, Karima; Mercier, Guy; Blais, Jean-François (2014). Pilot-scale counter-current acid leaching process for Cu, Pb, Sb, and Zn from small-arms shooting range soil. Journal of Soils and Sediments , vol. 14 , nº 8. p. 1359-1369. DOI: 10.1007/s11368-014-0880-x.

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Résumé

Purpose

The main objective of this study was to evaluate the potential of a counter-current leaching process (CCLP) on 14 cycles with leachate treatment at the pilot scale for Pb, Cu, Sb, and Zn removal from the soil of a Canadian small-arms shooting range.

Materials and methods

The metal concentrations in the contaminated soil were 904 ± 112 mg Cu kg⁻¹, 8,550 ± 940 mg Pb kg⁻¹, 370 ± 26 mg Sb kg⁻¹, and 169 ± 14 mg Zn kg⁻¹. The CCLP includes three acid leaching steps (0.125 M H₂SO₄ + 4 M NaCl, pulp density (PD) = 10 %, t = 1 h, T = 20 °C, total volume = 20 L). The leachate treatment was performed using metal precipitation with a ₅₋M NaOH solution. The treated effluent was reused for the next metal leaching steps.

Results and discussion

The average metal removal yields were 80.9 ± 2.3 % of Cu, 94.5 ± 0.7 % of Pb, 51.1 ± 4.8 % of Sb, and 43.9 ± 3.9 % of Zn. Compared to a conventional leaching process, the CCLP allows a significant economy of water (24,500 L water per ton of soil), sulfuric acid (133 L H₂SO₄ t⁻¹), NaCl (6,310 kg NaCl t⁻¹), and NaOH (225 kg NaOH t⁻¹). This corresponds to 82 %, 65 %, 90 %, and 75 % of reduction, respectively. The Toxicity Characteristic Leaching Procedure test, which was applied on the remediated soil, demonstrated a large decrease of the lead availability (0.8 mg Pb L⁻¹) in comparison to the untreated soil (142 mg Pb L⁻¹). The estimated total cost of this soil remediation process is 267 US$ t⁻¹.

Conclusions

The CCLP process allows high removal yields for Pb and Cu and a significant reduction in water and chemical consumption. Further work should examine the extraction of Sb from small-arms shooting range.

Type de document: Article
Mots-clés libres: acid leaching; antimony; contaminated soil; lead; small-arm shooting range
Centre: Centre Eau Terre Environnement
Date de dépôt: 10 avr. 2018 19:06
Dernière modification: 10 avr. 2018 19:06
URI: http://espace.inrs.ca/id/eprint/3593

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