Abstract
High-phosphorus iron ore is not used because of its high phosphorus content. Phosphorus is mainly present in fluorapatite. In this work, the phosphorus vaporization that occurs during the carbothermal reduction of fluorapatite was investigated. The thermodynamic principle of vaporization, which removes phosphorus during carbothermal reduction, was elucidated, and the mineral evolution of high-phosphorus iron ore was summarized. The results demonstrate that it was difficult to reduce fluorapatite when only carbon was added. When Al2O3, SiO2, and Fe2O3 were added, the dephosphorization of fluorapatite was stimulated, and the dephosphorization temperature decreased. A phosphorus-containing gas was generated during this process. SiO2 had the strongest effect on the dephosphorization of fluorapatite. The carbothermal reduction rate of fluorapatite accelerated when SiO2, Al2O3, and Fe2O3 were concurrently added. These oxides were advantageous for vaporization dephosphorization. The gas-phase volatiles were detected through gas-phase mass spectrometry. The volatiles were primarily P2 or PO. The temperature range of 1000–1100 °C was the optimum for vaporization dephosphorization. This article provides a theoretical and experimental basis for the development and utilization of high-phosphorus iron ore through vaporization dephosphorization.
Highlights
High-phosphorus oolitic hematite constitutes an important iron ore resource and is commonly found in central and northern Western Europe [1], Ukraine, and Canada
The development of smelting technology that is suitable for high-phosphorus iron ore is required in order to guarantee the supply of iron ore resources in China
All gangue oxides (Al2 O3, SiO2, and Fe2 O3 ) in the high-phosphorus iron ore promoted the dephosphorization of fluorapatite, while the promotion effect of SiO2 was the strongest
Summary
High-phosphorus oolitic hematite constitutes an important iron ore resource and is commonly found in central and northern Western Europe [1], Ukraine, and Canada. The high-phosphorus iron ore processing characteristics are based on the following: (1) The distribution of hematite and fluorapatite is embedded and finely grained. Both minerals are surrounded by layers that form a ring. This leads to difficulty during sorting and grinding. (3) Oolite is a sedimentary iron deposit of low hardness and that contains many clay minerals. The oolite produces higher iron-bearing slime and increases the sorting difficulty.
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