The compositions of the calcium aluminosilicatoferrite phases in commercial iron-ore sinters, which are solid solutions based on CaFe₄O₇, CaFe₂O₄, and Ca₂Fe₂O₅ ferrites of the CaO-Fe₂O₃ system, are studied. The sequence of the formation of the calcium aluminosilicatoferrites and their compositions with Ca₂SiO₄ and Ca₃SiO₅ silicates in sinters is found to be analogous to the crystallization of the ferrite and silicate phases in the ternary CaO-SiO₂-Fe₂O₃ system. This allows the phase diagram of this system to be used for the explanation of the formation of the mineral binder compositions for ore grains during sintering of commercial superfluxed sinters.