Phase Transitions and Structural Evolution of Manganese Ores During High-Temperature Treatment

Safarov R.Z. Baikenov Y.A. Zhandildenova A.K. Kopishev E.E. Kamatov R.M. Kargin J.B. Sanchez Cornejo H. Barnes C.H.W. De Los Santos Valladares L.
January 2025 Multidisciplinary Digital Publishing Institute (MDPI)

Metals
2025 #15 Issue 1

The aim of this research is to investigate the phase composition and structural peculiarities of complex metamorphic manganese ores from Central Kazakhstan before and after sintering in the temperature range of 600–1200 °C in an air atmosphere. X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and optical microscopy were used to analyze changes in elemental and phase composition. In their initial state, according to XRF analysis, the Bogach ore was manganese-rich, with a manganese content of 60.77 wt.%, while the Zhaksy ore contained manganese (44.88 wt.%), silicon (20.85 wt.%), and iron (6.14 wt.%) as its main components. In the Bogach ore samples, manganese content increased from 60.77% to 65.7% as the sintering temperature rose to 1100 °C, while the hausmannite phase (Mn₃O₄) emerged as the dominant phase, comprising 95.77% of the crystalline component at 1200 °C. Conversely, the Zhaksy ore samples displayed a sharp increase in braunite-phase (Mn₇O₁₂Si) content, reaching 83.81% at 1100 °C, alongside significant quartz amorphization. The degree of crystallinity in Bogach ore peaked at 56.2% at 900 °C but declined at higher temperatures due to amorphous phase formation. A surface morphology analysis revealed the transformation of dense, non-uniform particles into porous, granular structures with pronounced recrystallization as the temperature increased. In the Bogach samples, sintering at 900 °C resulted in elongated, needle-like crystalline formations, while at 1200 °C, tetragonal crystals of hausmannite dominated, indicating significant grain growth and recrystallization. For Zhaksy samples, sintering at 1100 °C led to a porous morphology with interconnected grains and microvoids, reflecting enhanced braunite crystallization and quartz amorphization. These findings provide quantitative insights into optimizing manganese oxide phases for industrial applications, such as catalysts and pigments, and emphasize the impact of thermal treatment on phase stability and structural properties. This research contributes to the development of efficient processing technologies for medium-grade manganese ores, aligning with Kazakhstan’s strategic goals in sustainable resource utilization.

braunite , hausmannite , manganese ore , phase transitions , quartz , sintering

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Department of Chemistry, Faculty of Natural Sciences, L.N. Gumilyov, Eurasian National University, Astana, 010008, Kazakhstan
Department of Science, L.N. Gumilyov, Eurasian National University, Astana, 010008, Kazakhstan
Department of Technical Physics, Faculty of Physics and Technical Sciences, L.N. Gumilyov, Eurasian National University, Astana, 010008, Kazakhstan
Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima, 15081, Peru
Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Ave., Cambridge, CB3 0HE, United Kingdom
Programa de Pós-Graduação em Ciências de Materiais, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Recife, 50670-901, Brazil

Department of Chemistry
Department of Science
Department of Technical Physics
Laboratorio de Cerámicos y Nanomateriales
Cavendish Laboratory
Programa de Pós-Graduação em Ciências de Materiais

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