The strength of the structure of iron ore pellets is one of the conditions for their successful transportation from manufacturer to consumer. Among the analyzed aspects of the formation of the pellet structure is the formation of calcium silicates (pyroxene-olivine series) in the mineral part of the cake, the influence of which is associated with a polymorphic transformation upon cooling, a change in the geometry of the crystals and an increase in internal stresses. The purpose of this work is to quantitatively assess the influence of this factor on the strength of pellets from highly enriched concentrates. A mathematical model and experimental data were used for the study. The obtained results confirm that when switching to the use of concentrates “rich” in iron, the role of the silicate binder in the formation of the strength of pellets decreases and the “ore mineral-ore mineral” type binder becomes more important. The probability of the formation of calcium silicates decreases when the silicon oxide content in the pellets is reduced from 6 to 3% (abs.). Accordingly, the negative impact of flux additives on strength due to softening of the structure will be reduced: the less calcium silicates in the structure, the lower the internal stresses in the cake during crystallization. The strength of pellets with increasing degree of concentrate enrichment is determined to a greater extent by the sintering of iron oxides than by the strength of the silicate binder. This, in turn, creates a request for the search for technical solutions to intensify the solid-phase sintering stage, optimal use of the free energy of the concentrate surface, and the formation of raw pellets with a uniform structure without defects (cracks, cavities, etc.). An increase in the probability (proportion) of the formation of calcium silicates for every 10% (rel.) leads to a decrease in the strength of the pellets by 0.8–2.03 daN, or by 3–8% (rel.).