Title: Secondary steel mill slags with pulp and paper mill solid residues for soil amendment: mineralogy, relevant physicochemical properties and trace element availability

Authors: Mikko Mäkelä; Hannu Nurmesniemi; Gary Watkins; Risto Pöykiö; Olli Dahl

Addresses: Department of Forest Products Technology, Aalto University, School of Chemical Technology, P.O. Box 16400, Tekniikantie 3, FI-00076 Aalto, Espoo, Finland. ' Stora Enso Oyj, Veitsiluoto Mill, FI-94830 Kemi, Finland. ' Department of Forest Products Technology, Aalto University, School of Chemical Technology, P.O. Box 16400, Tekniikantie 3, FI-00076 Aalto, Espoo, Finland. ' City of Kemi, Valtakatu 26, FI-94100 Kemi, Finland. ' Department of Forest Products Technology, Aalto University, School of Chemical Technology, P.O. Box 16400, Tekniikantie 3, FI-00076 Aalto, Espoo, Finland

Abstract: Inter-industrial utilisation of solid residues for soil amendment was investigated by combining secondary steel mill slags with residuals from a pulp and paper mill. Sample analysis included mineralogical characterisation by X-ray diffraction, relevant physicochemical properties and trace element availability by the original three-stage sequential BCR extraction procedure (CH₃COOH, NH₂OHHCl and H₂O₂ + CH₃COONH₄) and residual fraction determination by acid digestion (USEPA 3051A). Respectively, the pseudo-total concentrations of trace elements were determined according to USEPA method 3051A. Consequently, the alkalinity of the samples (pH values 12.1-12.2) suggests significant buffering and acid neutralisation capacity with liming effect values (34.9%-35.6%, Ca-equivalents, d.w.) comparable to commercial ground limestone. This was supported by XRD, which only revealed the existence of portlandite [Ca(OH) ₂] an calcite [CaCO₃]. Additionally, the pseudo-total concentrations of trace elements were lower than the respective limit values for EU soil improvers (2006/799/EC). However, Ba and V recovery during sequential extraction (Ba: 40.1-56.0 mgkg¹, d.w., by CH₃COOH; and V: 72.2-96.5 mgkg¹, d.w., by NH₂OHHCl) indicates potential phytoavailability.

Keywords: trace element availability; materials engineering; process industry; sequential extraction; soil amendment; solid residue; trace elements; secondary steel mill slags; pulp and paper mills; mineralogy; phytoavailability.

DOI: 10.1504/IJMATEI.2012.044452

International Journal of Materials Engineering Innovation, 2012 Vol.3 No.1, pp.1 - 16

Received: 21 Mar 2011
Accepted: 01 Aug 2011
Published online: 23 Aug 2014 *

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