Key Takeaways & Executive Findings
- •• A combined phase transformation and magnetic separation process effectively separates Fe and Mn from intergrown ferromanganese ore. • Optimal roasting conditions (600°C, 30 min) and grinding fineness (50% passing <0.074 mm) yield high Fe and Mn grades and recoveries. • Hematite transforms to magnetite and pyrolusite to manganosite, enabling efficient magnetic separation. • This clean utilization technology addresses the challenge of complex intergrown ferromanganese ore, reducing resource waste and environmental pollution.
Abstract
Intergrown ferromanganese ore resources are typical strategic mineral resources with huge reserves and abundant hematite, pyrolusite, and other valuable minerals, which is of great significance for its development and utilization. This paper adopts a combination of phase transformation and magnetic separation to explore the phase transformation mechanism of Fe minerals and Mn minerals during the roasting process. The analysis of the properties of the raw ore shows that the Fe-containing and Mn-containing minerals of the intergrown ferromanganese ore are hematite and pyrolusite, respectively. The optimal conditions for controlling the mineral phase were obtained, including roasting temperature of 600 ℃ for 30 min, and a grinding fineness of <0.074 mm accounting for 50%. Meanwhile, a Fe grade of 61.05% with a recovery of 80.77%, and a Mn grade of 61.60% with a recovery of 87.81% were acquired. The precise mineral phase transformation (MPT) could be realized via adjusting the roasting conditions. Hematite is transformed into magnetite, while pyrolusite is transformed into manganosite, and then they were effectively separated and concentrated via magnetic separation.
1. Introduction
Due to the relatively active chemical nature of Mn, it can combine with oxygen to form various types of manganese oxides. Manganese exists in nature mainly in the form of divalent manganese and tetravalent manganese, mainly including oxidized and carbonate ores. China's manganese ore imports were 2.93×10^7 t in 2024, with a degree of external dependence of more than 85% [1]. Due to the composition complexity of the intergrown ferromanganese ore, Fe and Mn with similar physical and chemical properties are difficult to achieve effective separation through traditional beneficiation techniques [2, 3]. Therefore, the research and development of independent innovative technology to realize the efficient comprehensive utilization of intergrown ferromanganese ore resources is of great strategic significance to strengthen China's ferromanganese resource security capacity.
Intergrown ferromanganese ore resources have a complex mineral composition, in which Fe element is mainly in hematite and limonite, and Mn element is mainly in pyrolusite and manganite. Around its development and utilization, mineral processing workers have carried out numerous studies [4−6]. LIU et al [7] introduced V2O5 as an additive and mixed it with iron manganese ore for roasting. They systematically studied the phase evolution law of the mixed roasting process, as well as the migration and separation law and recycling mechanism of manganese, iron, and vanadium elements in the acid leaching process. The results indicate that the manganese-containing phase in the roasted iron manganese ore is transformed into acid-soluble manganese pyrovanadate, while iron and silicon still exist in the form of Fe2O3 and SiO2. After acid leaching at pH 2 and at pH 1.8, respectively, the leaching rates of Mn, Fe, and V in roasted clinker were 81.25%, 0.0074%, and 5.77%, respectively, achieving effective separation of manganese and iron components [8]. At present, when such ferromanganese ore resources are processed by traditional sorting technology processes such as re-beneficiation, magnetic separation, flotation, leaching, or combined processes, only manganese concentrates with manganese grades of about 30% to 40% and manganese recoveries of about 50% to 60% can be obtained, and Fe ores are discarded in the row of rock ores and tailings, which results in resources waste and environmental pollution [9].
Mineral phase transformation (MPT) technology is a promising way to process the intergrown ferromanganese ore resources [10 −13]. Magnetic differences of Fe and Mn minerals are increased, enabling efficient separation through MPT [14−17]. In this paper, we put forward an MPT technical idea to realize efficient separation of Fe and Mn minerals in ferromanganese ore.
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CHEN Jia-li, GAO Peng, LIU Jie, ZHU Yi-min, ZHOU Wen-tao (2026). Precise mineral phase transformation and separation utilization technology for ferromanganese ore. Journal of Central South University. https://doi.org/10.1007/s11771-026-6237-y
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Frequently Asked Questions
What is the main challenge in processing intergrown ferromanganese ore?
The main challenge is the complex mineral composition and the similar physical and chemical properties of Fe and Mn, which make effective separation difficult using traditional beneficiation techniques.
What method is proposed in this paper for efficient separation?
The paper proposes a combination of mineral phase transformation (MPT) and magnetic separation. Roasting conditions are optimized to transform hematite to magnetite and pyrolusite to manganosite, enhancing magnetic differences for effective separation.
What are the optimal roasting conditions and results?
The optimal conditions are a roasting temperature of 600°C for 30 minutes and a grinding fineness of <0.074 mm accounting for 50%. Under these conditions, a Fe grade of 61.05% with a recovery of 80.77%, and a Mn grade of 61.60% with a recovery of 87.81% were achieved.
Why is this technology considered 'clean utilization'?
This technology enables efficient recovery of both Fe and Mn, reducing waste and environmental pollution compared to traditional methods that discard Fe ores in tailings. It also improves resource utilization efficiency.
What is the significance of this research for China?
China has a high external dependence on manganese ore imports (over 85% in 2024). This technology can strengthen China's ferromanganese resource security by enabling efficient utilization of domestic intergrown ferromanganese ore resources.
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