Behavior of vanadium and niobium during hot metal dephosphorization by CaO-SiO₂-Fe_tO slag

V and Nb are key elements for the production of high-grade steel. These elements are produced by few countries, and V has been nominated as a national stockpile element in Japan. Despite the importance of these elements, there are no strategies to obtain stable resources for them. Some types of iron ore that contain V and Nb can be used as sources of these elements. This study clarified the possibility of extracting V and Nb by means of a conventional hot metal dephosphorization process without using CaF₂ as a flux. First, the influences of V and Nb oxides on the distribution ratio of P₂O ₅ between the solid solution and liquid phases in slag were measured. Then, the behaviors of V and Nb in hot metal dephosphorization by CaO-SiO ₂-Fe_tO slag were investigated. Finally, a previously described hot metal simulation model was modified and the behaviors of various elements, including V and Nb, during hot metal dephosphorization were simulated, and the results were compared with experimental ones. The results are summarized as follows: (1) The addition of V and Nb oxides slightly increases the distribution ratio of P₂O₅ between the solid solution and liquid phases in slag. (2) The decreasing rate of the elements by the flux addition can be expressed as Nb < Mn < P < V, and these decreasing rates increase as the basicity increases. (3) The simulation results for the behavior of P and V or Nb are in good agreement with the experimental results; that is, the decreasing rate for Nb is greater than that for P, and the separation of Nb leaving P in the hot metal is easier than the separation of V.