Title: Slaker grits from the causticising process of a pulp mill – a potential fertiliser and liming agent material for use in agriculture and forestry

Authors: Hannu Nurmesniemi, Olli Dahl, Gary Watkins, Risto Poykio

Addresses: Stora Enso Oyj, Veitsiluoto Mill, FI-94830 Kemi, Finland. ' Department of Forest Products Technology, Aalto University School of Science and Technology, P.O. Box 6300, FI-02015 Espoo, Finland. ' Department of Forest Products Technology, Aalto University School of Science and Technology, P.O. Box 6300, FI-02015 Espoo, Finland. ' City of Kemi, Valtakatu 26, FI-94100 Kemi, Finland

Abstract: The total heavy metal concentrations in the slaker grits were clearly lower than current Finnish limit values for fertilisers used in agriculture and in forestry. This result, together with the strongly alkaline pH (13), the elevated total calcium concentration (331 g kg−1; d.w.), the existence of calcite (CaCO3), as well as the neutralising value of 39.4-% (Ca equivalents, d.w.), according to which, 0.96 tonnes of slaker grits would be required to replace 1 tonne of a commercial ground limestone product, indicate that the slaker grits are a potential fertiliser and liming agent material for use in agriculture and forestry.

Keywords: chemical recovery; fertilisers; heavy metals; kraft pulp; liming; non-process elements; pulping; pulp mills; waste; causticising; slaker grits; Finland; agriculture; forestry; calcium concentration; calcite.

DOI: 10.1504/IJMATEI.2010.035159

International Journal of Materials Engineering Innovation, 2010 Vol.1 No.3/4, pp.312 - 324

Published online: 10 Sep 2010 *

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