Barium M-type hexagonal ferrite (BaM, BaFe12O19) is an immensely important magnetic material, which we have successfully made from the simple valorisation of Fe-rich industrial waste from steel wire drawing, with addition of BaCO3 and heating in air to 1000 8C. The optimum ratio of Fe.Ba (producing 86 wt% BaM) was found to be 11:1 (non-stoichiometric), and secondary phases of a-Fe2O3 (non-magnetic) and ZnFe2O4 (poorly antiferromagnetic) were always present. This material consisted of small submicron platelets. A hard magnetic ferrite was produced with Ms=48.6 A m2 kg–1 and Hc=211.5 kA m–1. The highest density was achieved by sintering samples with Fe:Ba ratios of 11:1 and 12:1 at 1200 8C / 2 hr, with an increase in grain size up to 2 mm. The sintered 11:1 had electrical conductivity comparable to that of commercial sintered BaM. Such materials are suitable for industrial applications as hard magnets, and EM shielding in architectural and construction materials.
Pullar R.C., Saeli M., Novais R.M., Amaral J.S., Labrincha J.A. (2016). Valorisation of industrial iron oxide waste to produce magnetic barium hexaferrite. CHEMISTRYSELECT, 1(4), 819-825 [10.1002/slct.201500042].
Valorisation of industrial iron oxide waste to produce magnetic barium hexaferrite
Saeli M.;
2016-01-01
Abstract
Barium M-type hexagonal ferrite (BaM, BaFe12O19) is an immensely important magnetic material, which we have successfully made from the simple valorisation of Fe-rich industrial waste from steel wire drawing, with addition of BaCO3 and heating in air to 1000 8C. The optimum ratio of Fe.Ba (producing 86 wt% BaM) was found to be 11:1 (non-stoichiometric), and secondary phases of a-Fe2O3 (non-magnetic) and ZnFe2O4 (poorly antiferromagnetic) were always present. This material consisted of small submicron platelets. A hard magnetic ferrite was produced with Ms=48.6 A m2 kg–1 and Hc=211.5 kA m–1. The highest density was achieved by sintering samples with Fe:Ba ratios of 11:1 and 12:1 at 1200 8C / 2 hr, with an increase in grain size up to 2 mm. The sintered 11:1 had electrical conductivity comparable to that of commercial sintered BaM. Such materials are suitable for industrial applications as hard magnets, and EM shielding in architectural and construction materials.
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