Immobilisation of lead smelting slag within spent aluminate-fly ash based geopolymers

M. B. Ogundiran*, H. W. Nugteren, G. J. Witkamp

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


This study presents the solidification/stabilisation and immobilisation of lead smelting slag (LSS) by its incorporation in coal fly ash - blast furnace slag based geopolymers. It also explores the use of a spent aluminium etching solution (AES) as geopolymer activator instead of the commonly used silicate solutions. The compressive strength of the geopolymers produced with the AES was lower than when applying a K-silicate solution as activator (100. MPa versus 80. MPa after 28 days). Compressive strength was not affected when up to 10% of the FA was replaced by LSS. NEN 12457-4, TCLP, SPLP and NEN 7375 leaching tests indicated that mobile Pb from LSS was highly immobilised. The diffusion leaching test NEN 7375 revealed exceeding of the Dutch Soil Quality Regulation threshold limits only for Se and Sb. On the condition that the remaining excess leaching can be reduced by further refinement of the mixture recipes, the proposed process will have the potential of producing waste-based construction materials that may be applied under controlled conditions in specific situations.

Original languageEnglish (US)
Pages (from-to)29-36
Number of pages8
JournalJournal of hazardous materials
Issue number1
StatePublished - Mar 5 2013
Externally publishedYes


  • Aluminium etching solution
  • Coal fly ash
  • Geopolymer
  • Immobilisation
  • Lead smelting slag

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis


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