Isomorphism of Iron and Magnesium as Hardening Factor for Magnesial Pellets from Concentrate Extracted at Mikhailovskoe Deposit

The production of magnesium-fluxed iron ore pellets is one of the topical areas of the modern blast-furnace melting process. Earlier on, a positive influence of magnesium oxide as part of blast-furnace slag on the strength of pellets from the Mikhailovskoe deposit was recognized. According to the work results, Mg²⁺ and Fe²⁺ have similar atomic radii and isomorphically replace one another in silicate minerals of a bond of pellets. The obtained data show that the fluxing of pellets with calcic and magnesium oxides and a relatively high content of silicon oxide in the concentrate (6–8%) simultaneously lead to a concentration of calcium, sodium, potassium and magnesium in the silicate bond. At the same time, the increase in basicity leads to the formation of pyroxene bond and a decrease in strength. The addition of magnesium oxide moves the bond to the region of pyroxene livine and, then, olivine composition with Fe- and Mg-enriched silicates. Not only does the magnesium oxide concentration rise but this oxide also replaces iron in the structure of silicate. A hypothesis has been set forth that the strength of fluxed pellets can be increased by replacing iron with manganese (Fe²⁺ \( \to \) Mn²⁺); together, these compounds might be isomorphically included in the structure of silicates.