Abstract
AbstractIron ore sinters prepared for the blast furnaces at Scunthorpe, Humberside, comprise iron oxides bound in a matrix of aluminium- and silicon-rich calcium ferrites with some calcium orthosilicate and a residual silicate glass. A super-silicon-deficient clinopyroxene with up to half of the Si in the chain replaced by Fe3+ and Al3+ precipitates from the glass in some areas. The iron oxides are principally magnetite and hematite with some wüstite in highly reduced areas. The calcium orthosilicate has been previously reported as the mineral larnite, β-Ca2SiO4. This study found a range of Fe for Ca substitution and three polymorphs were recognised: the range Ca2SiO4 to Ca1.85Fe0.15SiO4 has the structure of larnite; the range Ca1.85Fe0.15SiO4 to Ca1.6Fe0.4SiO4 has the structure of bredigite, α′-Ca2SiO4. Iron substitution beyond this, and up to a maximum of about Ca1.5Fe0.5SiO4, was not recognisable as a polymorph of Ca2SiO4, but an orthorhombic cell is tentatively proposed. The complex ferrite SFCA (silico-ferrite of Ca and Al) is variable in composition, but has a minimum of about 3 wt. % Al2O3 and contains 20 wt. % CaO and SiO2 with a Ca: Si ion ratio of about 2 : 1. A C-face centred monoclinic cell has been deduced: a 15.70, b 9.70, c 8.48 Å; β 105°30′. The Al appears critical for the formation of SFCA in sinter; without it, a eutectic of magnetite and bredigite precipitates in preference.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
