Use of industrial wastes in the formulation of olivine green pigments

authors	Esteves, D; Hajjaji, W; Seabra, MP; Labrincha, JA
nationality	International
journal	JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords	Ni-olivine; Green pigments; Galvanising waste; Foundry sand
keywords	GALVANIC SLUDGE; SILICATE MELTS; CHROMIUM; SPECTRA; NICKEL; LIEBENBERGITE; GLASSES; IONS; RECOVERY; NI2SIO4
abstract	This work describes the formulation and synthesis of Ni-olivine green pigments from industrial wastes, namely foundry sand and a sludge resulting from the wastewater treatment of the Ni/Cr galvanising process. This second one is considered as hazardous waste since the leached levels of nickel and chromium are above legal concentrations. Pigments were prepared by the solid state reaction method and Ni2SiO4 is formed at only 1050 degrees C. SiO2 (in excess) and NiCr2O4 are present as secondary phases. By using pure reagents and following similar processing conditions, the Ni-olivine phase is only observed at 1200 degrees C. The green colour of the pigments is due to spin-allowed transitions of Ni2+ in octahedral M1 and M2 positions. The sample prepared from wastes shows a stronger and darker green hue. The colouring performance of ceramic glazes and bodies is also optimal, confirming the potential of the use of such wastes for ceramic pigments production. (C) 2010 Elsevier Ltd. All rights reserved.
publisher	ELSEVIER SCI LTD
issn	0955-2219
year published	2010
volume	30
issue	15
beginning page	3079
ending page	3085
digital object identifier (doi)	10.1016/j.jeurceramsoc.2010.07.006
web of science category	Materials Science, Ceramics
subject category	Materials Science
unique article identifier	WOS:000282070200010