Magnetization roasting followed by magnetic separation can upgrade ferruginous manganese raw materials, but its efficiency depends on the iron phase state after roasting. This study clarified the phase state and distribution of iron in magnetic and non-magnetic products obtained from ferruginous manganese ore and concentrate after magnetization roasting and dry magnetic separation. The materials were roasted at 600–650 °C using Shubarkol coal as a solid reducing agent and then separated at a magnetic field strength of 1.2 kOe. Chemical analysis, X-ray diffraction, and Mössbauer spectroscopy were used to relate separation results to iron phase states. The Mn/Fe ratio in the non-magnetic products increased from 3.92 to 10.87 for the ore and from 2.98 to 23.99 for the concentrate, while 76.25% and 88.26% of iron were transferred to the corresponding magnetic fractions. Mössbauer spectroscopy showed that magnetite-type spinel components, including Fe₃O₄ and substituted (Fe_1−xM_x)₃O₄, were mainly associated with the magnetic products. Hematite-like and paramagnetic Fe³⁺/Fe²⁺ components were also detected, indicating incomplete conversion of iron-bearing phases into magnetite-type spinels. The Mössbauer-area-weighted fraction of iron in magnetite-type spinel phases was 76.5% for the ore and 64.36% for the concentrate. These results explain the different separation behavior after roasting–magnetic treatment.

The selective transformation of iron-bearing phases in ferruginous manganese ores requires control of temperature and local reducing conditions. This study examines temperature-dependent relationships in the Fe–Mn–C–O system through thermodynamically guided geometrical constructions using a stoichiometric approximation. Boundary ternary systems were triangulated, followed by tetrahedral subdivision of the quaternary composition space at 550, 750, 950, and 1150 °C. A key temperature-dependent feature is the direct adjacency of Fe₃O₄-containing and metallic-Fe-containing subdivisions at 550 °C, whereas FeO-containing subdivisions form an intermediate zone at 750–1150 °C. These relationships were qualitatively compared with room-temperature Mössbauer spectra of three roasted ferruginous manganese ore samples. At 500–550 °C with 30% coal, magnetite/spinel-like components accounted for 72.4% of the spectral area, compared with 20.7% at 500–650 °C with 10% coal. Hematite-like components predominated at 500–550 °C with 10% coal, accounting for 92.7%. No independently resolved FeO-type component was identified in the cooled products. The comparison demonstrates a pronounced redistribution of iron-bearing environments between the investigated roasting regimes, with the largest magnetite/spinel-like contribution obtained at the higher coal addition. The combined analysis links temperature-dependent end-member relationships with spectroscopic evidence of iron transformation and provides a framework for interpreting magnetizing-roasting behavior.