A laboratory column study of arsenic transport and sorption by recycled Nickel smelter slag

Saidur R. Chowdhury, Ernest K. Yanful

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geoenvironmental Engineering

ABSTRACT: The application of iron oxide-rich slag in remediation technologies has great potential in subsurface treatment. In the present study, recycled fayalite-iron oxides loaded Ni-smelter slag, obtained from Vale Inco Ni smelter near Sudbury, ON, Canada was evaluated for environmental remediation. The broad aim of the research was to assess the potential of the slag as a reactive medium in permeable reactive barriers (PRB) at contaminated sites. The results of the study showed that 10.16-11.43 cm long columns containing 451-550 g of slag and operated for at least 65 days were capable of removing 99-100 percent As species from continuously flowing contaminated water with an initial As concentration of 10 mg/L. The removal capacities were found to be 1.71 to 1.78 mg As per g of slag. Effluent samples collected at different operation periods (e.g., 15.5 61.5, 75.5 and 93.5 days) were used for chemical speciation modeling. The MINTEQ results indicated that the effluent solutions were supersaturated with respect to goethite, hematite, ferrihydrite, lepidocrocite, and maghemite, as indicated by the positive saturation indices. The speciation modeling also predicted the presence of FeOH+, Fe(OH)2+, Fe(OH)3, Fe(OH)4-, Fe2(OH)2+4, Fe3(OH)4+5, FeOH+2, NiNO3+, and Ca(NO3)2 as possible dissolved complexes, and Ca3(AsO4)2:4H2O, FeAsO4:2H2O, Ni3(AsO4)2:8H2O, and Ni(OH)2 as possible mineral formations. The results also indicated the possible formation of scorodite, FeAsO4:2H2O, and annabergite, Ni3(AsO4)2:8H2O, from solution suggesting that As was chemically sorbed on the Ni smelter slag. The presence of FeAsO4:2H2O was corroborated with XPS and Raman spectroscopy data. The research provided an opportunity to evaluate the feasibility of using slag (e.g. an iron oxide and iron silicate bearing waste from Ni-ore smelting) in environmental remediation, and to highlight the benefits of using recycled waste products for contaminated subsurface restoration. Keywords: Reactive medium, chemical speciation, recycled slag, remediation

RÉSUMÉ: L'application de fer laitier riche en oxyde de technologies d'assainissement a un grand potentiel dans le traitement du sous-sol. Dans la présente étude, les recyclés d'oxydes fayalite-fer chargés de laitier Ni-fonderie, obtenu au fonderie Vale Inco Ni près de Sudbury, ON, Canada, a été évalué pour l'assainissement de l'environnement. L'objectif général de l'étude était d'évaluer le potentiel du laitier comme un milieu réactif dans barrières réactives perméables (PRB) sur les sites contaminés. Les résultats de l'étude ont montré que les colonnes de 10,16 à 11,43 cm de long contenant 451 à 550 g de scories et exploité pendant au moins 65 jours ont été capables d'éliminer 99-100 pourcent d'espèces As de s'écouler en continu, l'eau contaminée contenant une concentration initiale de 10 mg / L. Les capacités d'enlèvement se sont révélés être de 1,71 à 1,78 mg par g de scories. Échantillons d'effluents prélevés à différentes périodes de fonctionnement (par exemple, 15,5 à 61,5, 75,5 et 93,5 jours) ont été utilisées pour la modélisation de la spéciation chimique. Les résultats de MINTEQ indiquent que les solutions d'effluent ont été sursaturée par rapport à la goethite, l'hématite, la ferrihydrite, la lépidocrocite, la maghémite et, comme indiqué par les indices de saturation positifs. Les résultats indiquent également la formation possible de scorodite, FeAsO4:2H2O, et annabergite, Ni3(AsO4)2:8H2O, de la solution qui suggère que tant a été chimiquement adsorbé sur la fonderie laitier Ni. La présence de FeAsO4:2H2O a été corroborée par XPS et les données de spectroscopie Raman. La recherche a permis d'évaluer la faisabilité de l'utilisation de scories (par exemple, un oxyde de fer et de silicate de fer portant déchets de Ni-fusion du minerai) en assainissement de l'environnement, et à mettre en évidence les avantages de l'utilisation des déchets recyclés pour contaminée restauration du sous-sol. 1. Introduction Arsenic, a toxic metalloid, is a part of the earth's crust and ranks twentieth in abundance (Mandal and Suzuki, 2002). Arsenic species are distributed in the environment (soil, water and air) through many pathways, both naturally such as through weathering, volcanic eruptions and water-rock interaction as well as via human activity such as mining, agricultural activities, electronics and metallurgy (Chowdhury et al. 2010). Since industrialization and civilization grew over the last century, there has been an increase in the release of As contaminated waste products into the environment. Industries such as mining, ore smelting, and manufacturing release arsenic, lead, iron, chromium and nickel, and organic pollutants (Reuter et al. 2004; Wilkens et al. 2003). The major risks posed by these metals are

Please include this code when submitting a data update: GEO2014_285

Access this article:
Canadian Geotechnical Society members can access to this article, along with all other Canadian Geotechnical Conference proceedings, in the Member Area. Conference proceedings are also available in many libraries.

Cite this article: