The influence of heavy metals on the polymorphs of dicalcium silicate in the belite-rich clinkers produced from electroplating sludge

J Hazard Mater. 2009 Oct 15;170(1):443-8. doi: 10.1016/j.jhazmat.2009.04.076. Epub 2009 Apr 24.

Abstract

The purpose of this study is to utilize an electroplating sludge for belite-rich clinker production and to observe the influence of heavy metals on the polymorphs of dicalcium silicate (C(2)S). Belite-rich clinkers prepared with 0.5-2% of NiO, ZnO, CuO, and Cr(2)O(3) were used to investigate the individual effects of the heavy metals in question. The Reference Intensity Ratio (RIR) method was employed to determine the weight fractions of gamma-C(2)S and beta-C(2)S in the clinkers, and their microstructures were examined by the transmission electron microscopy (TEM). The results showed that nickel, zinc, and chromium have positive effects on beta-C(2)S stabilization (Cr(3+)>Ni(2+)>Zn(2+)), whereas copper has a negative effect. The addition of up to 10% electroplating sludge did not have any negative influence on the formation of C(2)S. It was observed that gamma-C(2)S decreased while beta-C(2)S increased with a rise in the addition of the electroplating sludge. Moreover, nickel and chromium mainly contributed to stabilizing beta-C(2)S in the belite-rich clinkers produced from the electroplating sludge.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium Compounds / chemistry*
  • Chromium
  • Conservation of Natural Resources / methods
  • Electroplating*
  • Glass Ionomer Cements / chemical synthesis*
  • Metals, Heavy / chemistry*
  • Nickel
  • Refuse Disposal / methods*
  • Sewage
  • Silicates / chemistry*
  • Zeolites / chemical synthesis*
  • Zinc

Substances

  • Calcium Compounds
  • Glass Ionomer Cements
  • Metals, Heavy
  • Sewage
  • Silicates
  • belite
  • Chromium
  • dicalcium silicate
  • Zeolites
  • Nickel
  • Zinc