Chromatic properties of industrial solid waste based ferrites

The hexaferrite and monoferrite powders were prepared by the common solid state reaction method. Similar formulations have been prepared but using chemically- pure commercial reagents or by using a sludge generated by steel wiredraw process as source of iron oxide. This iron-rich industrial waste is mainly composed of Fe2O3 (62 wt%). Zinc and calcium are present in minor quantities and can form complexes such as franklinite (ZnFe2O4) and apatite (Ca5(PO4) 3(OH,F,Cl)). Ni/Cr galvanising sludge was also used to enhance the black coloration of monoferrite. After calcination of the mixtures at 1,000 °C and 1,050 °C, typical X-ray diffraction patterns of the expected SrFe12O19 and NiFe2O4 phases were obtained, together with minor peaks of spinel-type (SrFe2O 4 and ZnFe2O4) and Fe2O3 phases. Anyway, this resulted in a black pigment with chromatic properties comparable to those of commercial formulations, such as iron cobalt chromite (Fe,Co)(Fe,Cr)2O4 (DCMA 13-40-9), chrome iron nickel (Ni,Fe)(Fe,Cr)2O2 (DCMA 13-50-9), and manganese ferrite (Fe,Mn)(Fe,Mn)2O4 (DCMA 13-41-9). © Springer Science+Business Media B.V. 2012.