resumo
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 (Ca-5(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 degrees C and 1,050 degrees C, typical X-ray diffraction patterns of the expected SrFe12O19 and NiFe2O4 phases were obtained, together with minor peaks of spinel-type (SrFe2O4 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)(2)O-4 (DCMA 13-40-9), chrome iron nickel (Ni,Fe)(Fe,Cr)(2)O-4 (DCMA 13-50-9), and manganese ferrite (Fe,Mn)(Fe,Mn)(2)O-4 (DCMA 13-41-9).
categoria
Environmental Sciences & Ecology
autores
Hajjaji, W; Pullar, R; Seabra, MP; Labrincha, JA
nossos autores
João António Labrincha Baptista
Professor Catedrático
Maria Paula Seabra
Professor Auxiliar
Rob Pullar
Colaborador
Walid Hajjaji
Bolseiro de pós-Doutoramentoagradecimentos
The work was supported by FCT-CNR joint project 2011-2012