Olivine-based slag from a HCFeMn pilot
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Olivine-based slag from a HCFeMn pilot

by Sophie Graul, Tallinn University of Technology, Tallinn, Estonia and France

During a pyrometallurgy pilot, unusual slags were produced due to a composition that was too rich in calcium and silicon and the excessive presence of fluorine - due to the use of fluorite to fluidify the system.

This led to the formation of a viscous slag rich in massive olivines, stable at high temperatures (above 1300°C). The photo shows marked zonation between the magnesium-rich core (purple) and the manganese-rich rim (orange). Numerous Mn-sulphide dendrites can also be seen (yellow), as well as spinels (black).