Skip to main content

Structural investigations on iron-ore sinter phases – crystallography meets applied mineralogy

Sinter plants are an integral part for the preparation of iron ores for the blast furnace process. In a series of complex reactions, semi-molten, centimeter-sized aggregates are formed containing ore particles cemented by a matrix of Ca-rich ferrites that contain some silica and alumina. For these compounds, the acronym SFCA (Silico-Ferrites of Calcium and Aluminum) was coined. The SFCA phases with general composition A14+6nO20+8n (A: Ca, Mg, Fe2+, Fe3+, Al3+, Si4+) act as the binder that keeps the sinters intact in order to withstand the loads in a blast furnace.

Depending on the value of n in the chemical formula, four different SFCA-phases can be distinguished forming a polysomatic series. They can be described with a modular approach involving the stacking sequence of “P” and “S” modules that can be imagined as being cut from the well-known pyroxene and spinel structure-types. The representatives with n = 0 (A14O20) are related to the sapphirine supergroup of minerals.

Even though the SFCAs are critical for the production of iron-ore sinters, it is surprising that there are still many open questions regarding their composition, atomic structure, thermochemistry and stability. For any target-oriented improvement and optimization of ore-sintering as well as thermodynamic modeling of the sinters, a much more detailed understanding of these fundamental solid-state properties of the SFCAs is essential. The present contribution provides - for the first time - a detailed crystallographic analysis on the impact of chemical variations on these compounds that are of relevance for the field of applied mineralogy.


Volker Kahlenberg1, Hannes Krüger1
1University of Innsbruck, Austria
GeoMinKöln 2022