Clean production of Fe-based amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore and apatite

Abstract

Separated preparation of prealloys and amorphous alloys results in severe solidification–remelting and beneficial element removal–readdition contradictions, which markedly increase energy consumption and emissions. This study offered a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore (HPIO) and apatite. First, the thermodynamic conditions and equilibrium states of the carbothermal reduction reactions in HPIO were calculated, and the element content in reduced alloys was theoretically determined. The phase and structural evolutions, as well as element migration and enrichment behaviors during the smelting reduction of HPIO and Ca₃(PO₄)₂, were then experimentally verified. The addition of Ca₃(PO₄)₂ in HPIO contributes to the enrichment of the P element in reduced alloys and the subsequent development of Fe₃P and Fe₂P phases. The content of P and C elements in the range of 1.52wt%–14.63wt% and 0.62wt%–2.47wt%, respectively, can be well tailored by adding 0–50 g Ca₃(PO₄)₂ and controlling the C/O mole ratio of 0.8–1.1, which is highly consistent with the calculated results. These FePC alloys were then successfully formed into amorphous ribbons and rods. The energy consumption of the proposed strategy was estimated to be 2.00 × 10⁸ kJ/t, which is reduced by 30% when compared with the conventional production process. These results are critical for the comprehensive utilization of mineral resources and pave the way for the clean production of Fe-based amorphous soft magnetic alloys.

Keywords

high-phosphorus iron ore / smelting reduction / structural evolution / Fe-based amorphous alloy / clean production

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