Abstract

It is particularly significant to investigate the reduction behavior and existing form of phosphorus in metal and slag phase during coal-based reduction for the efficient development and utilization of high-phosphorus oolitic hematite. The reduction behavior of phosphorus minerals and their existing form in the metal and slag phase during the coal-based reduction of high phosphorus oolitic hematite were systematically investigated using HSC software simulation, thermodynamic calculation, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS). The results show that after Fe2O3 was reduced to metal iron, the reduction of apatite was promoted by providing the most inclined enrichment site of phosphorus (metallographic phase). Phosphorus existed mainly in two forms in the metal phase—one was in the form of Fe3P compound at the boundary of the metal phase, and the other was in the form of solid solution in the metal iron. There were two forms of phosphorus in the slag phase—one was incompletely reacted apatite, and the other was formed as CaO–SiO2–P2O5 solid solution. In the early stage of coal-based reduction, phosphorus in the slag phase mainly existed in the form of apatite, while in the later stage, it mainly existed in the form of CaO–SiO2–P2O5 solid solution.

Highlights

  • Despite the abundant reserves of iron ore resources in China, the overall iron ore is characterized by the behavior of low grade, fine grain size, and high impurities, resulting in the situation of importing large quantities of iron ore from abroad and the unavailability of domestic resources for many years [1,2,3,4]

  • Due to its high phosphorus content, fine size of iron ore, and complex mineral composition, it is impossible for traditional single mineral processes such as gravity separation, magnetic separation, and flotation to beneficiate effectively and independently to meet industrial needs due to the limitations of their own processes [7,8,9,10,11]

  • In order to realize the comprehensive utilization of high phosphorus oolitic hematite, the combined treatment of beneficiation and metallurgy should be more promising [16,17,18,19]

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Summary

Introduction

Despite the abundant reserves of iron ore resources in China, the overall iron ore is characterized by the behavior of low grade, fine grain size, and high impurities, resulting in the situation of importing large quantities of iron ore from abroad and the unavailability of domestic resources for many years [1,2,3,4]. Oolitic hematite ore with a total reserve of 3.72 billion tons has been unable to be exploited and utilized on a large scale due to its complex characteristics, causing a great waste of resources [5,6]. Since the 1930s, scholars at home and abroad have made many explorations and studies on the beneficiation of high phosphorus oolitic hematite. Due to its high phosphorus content, fine size of iron ore, and complex mineral composition, it is impossible for traditional single mineral processes such as gravity separation, magnetic separation, and flotation (including positive flotation and reverse flotation) to beneficiate effectively and independently to meet industrial needs due to the limitations of their own processes [7,8,9,10,11]. Scholars at home and abroad try to use a combined separation process to treat oolitic hematite. In order to realize the comprehensive utilization of high phosphorus oolitic hematite, the combined treatment of beneficiation and metallurgy should be more promising [16,17,18,19]

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