Journal of Material Cycles and Waste Management

, Volume 18, Issue 1, pp 132–145

Digestion reactions of paper sludge combustion ash in strong alkaline solutions at 60 °C

  • Andrea Hartmann
  • Valeriy Petrov
  • Josef-Christian Buhl
  • K. Rübner
  • M. Lindemann
ORIGINAL ARTICLE

DOI: 10.1007/s10163-014-0320-4

Cite this article as:
Hartmann, A., Petrov, V., Buhl, JC. et al. J Mater Cycles Waste Manag (2016) 18: 132. doi:10.1007/s10163-014-0320-4

Abstract

Alkaline reactions of paper sludge combustion ash at low temperature (60 °C) were performed using a calcite-rich paper ash (PA 1) and a gehlenite-rich ash (PA 2). Strong alkaline conditions (8, 12, 16 M NaOH) were revealed at reaction times of 1–4 h and 12–24 h. Reactions were performed with pure ashes and in the presence of NaAlO2. The products were characterized by XRD, FTIR, SEM/EDX, gravimetry and chemical analysis. The conversion was found to proceed mainly in the period between 1 and 4 h. Portlandite and hydrogarnet were observed from PA 1 in 8 M NaOH. Onset of formation of Ca4Al2O6CO3.11H2O beside Ca(OH)2 could be analyzed after reaction of PA 1 in 12 M and 16 M NaOH. Addition of NaAlO2 favored crystallization of hydrogarnet and Ca4Al2O6CO3.11H2O. For PA 2 gehlenite remained stable, but a high portlandite fraction was observed. Addition of NaAlO2 yielded hydrogarnet beside gehlenite in 8 M NaOH. Higher alkalinities favored crystallization of Ca4Al2O6CO3.11H2O and onset of dissolution of gehlenite. Finally transformation of Ca4Al2O6CO3.11H2O into sodium aluminum silicate hydrate was observed. All results were discussed with regard to heavy metal distribution of the initial PA between the alkaline digestion solution and the products. In conclusion suitable applications of the products were proposed.

Keywords

Paper sludge combustion ash Alkaline digestion reaction Portlandite Katoite Zeolite 

Copyright information

© Springer Japan 2014

Authors and Affiliations

  • Andrea Hartmann
    • 1
  • Valeriy Petrov
    • 1
  • Josef-Christian Buhl
    • 1
  • K. Rübner
    • 2
  • M. Lindemann
    • 2
  1. 1.Institute of MineralogyLeibniz University HannoverHannoverGermany
  2. 2.Federal Institute for Materials Research and TestingDivison 7.4., Technology of Construction MaterialsBerlinGermany