The Bayan Obo iron ore contains valuable metallic elements such as niobium and rare earth elements. However, developing appropriate metallurgical processes to achieve effective dephosphorization of Nb-bearing hot meta...The Bayan Obo iron ore contains valuable metallic elements such as niobium and rare earth elements. However, developing appropriate metallurgical processes to achieve effective dephosphorization of Nb-bearing hot metal meanwhile retaining Nb in the steel products remains a challenge. We carried out a thermodynamic study on dephosphorization of Nbbearing hot metal and investigated the effects of the initial [C] content and the dephosphorization temperature on oxidation behaviors of [Nb] and [P]. In particular, we focused on thermodynamic analysis of dephosphorization of Nb-bearing hot metal with highly basic BaO-based slag. The results showed that the highly basic BaO-based slag system is more suitable for dephosphorization under oxidative conditions, and increasing the [C] content favors dephosphorization of Nb-bearing hot metal without oxidizing [Nb]. Moreover, the values of equilibrium oxygen activity for oxidation reactions of [Nb] and [P] are increased as the dephosphorization temperature increases. Considering the hot metal containing 0.02% of [Nb] in Baotou Steel, thermodynamic calculations indicated that the content of [P] can be reduced to 0.02%–0.05% and [Nb] remains unoxidized when dephosphorization occurs at the cconditions of T=1573–1673 K, [C]=4.0%, [Nb]=0.02%, aP2O5=10-24, aNb2O5=10-10.展开更多
Laboratory study was carried out on deep dephosphorization of liquid steel byBaO-based fluxes at 1600°C to achieve ultra low phosphorus level in the steel. A dynamic model ofdephosphorization of Liquid steel by B...Laboratory study was carried out on deep dephosphorization of liquid steel byBaO-based fluxes at 1600°C to achieve ultra low phosphorus level in the steel. A dynamic model ofdephosphorization of Liquid steel by BaO-based fluxes was established. According to the model, thecontrolling step of dephosphorization by BaO-based fluxes was the mass-transfer of phosphorus insteel phase under the condition of low phosphorus liquid steel. It is estimated that the apparentrate constant of dephosphorization by BaO-based fluxes was 0.4xl0^(-3)-8.2xl0^(-3) g/(cm^2 centre tos) and the mass-transfer coefficient of phosphorus in bulk steel was 0.025-0.04 cm/s.展开更多
基金Item Sponsored by Inner Mongolia Natural Science Foundation of China(2011MS0726)Inner Mongolia University of Science and Technology Innovation Foundation of China(2009NC016)Inner Mongolia Key Laboratory for Utilization of Bayan Obo Multi-metallic Resources Foundation of China(BO-13-003)
文摘The Bayan Obo iron ore contains valuable metallic elements such as niobium and rare earth elements. However, developing appropriate metallurgical processes to achieve effective dephosphorization of Nb-bearing hot metal meanwhile retaining Nb in the steel products remains a challenge. We carried out a thermodynamic study on dephosphorization of Nbbearing hot metal and investigated the effects of the initial [C] content and the dephosphorization temperature on oxidation behaviors of [Nb] and [P]. In particular, we focused on thermodynamic analysis of dephosphorization of Nb-bearing hot metal with highly basic BaO-based slag. The results showed that the highly basic BaO-based slag system is more suitable for dephosphorization under oxidative conditions, and increasing the [C] content favors dephosphorization of Nb-bearing hot metal without oxidizing [Nb]. Moreover, the values of equilibrium oxygen activity for oxidation reactions of [Nb] and [P] are increased as the dephosphorization temperature increases. Considering the hot metal containing 0.02% of [Nb] in Baotou Steel, thermodynamic calculations indicated that the content of [P] can be reduced to 0.02%–0.05% and [Nb] remains unoxidized when dephosphorization occurs at the cconditions of T=1573–1673 K, [C]=4.0%, [Nb]=0.02%, aP2O5=10-24, aNb2O5=10-10.
文摘Laboratory study was carried out on deep dephosphorization of liquid steel byBaO-based fluxes at 1600°C to achieve ultra low phosphorus level in the steel. A dynamic model ofdephosphorization of Liquid steel by BaO-based fluxes was established. According to the model, thecontrolling step of dephosphorization by BaO-based fluxes was the mass-transfer of phosphorus insteel phase under the condition of low phosphorus liquid steel. It is estimated that the apparentrate constant of dephosphorization by BaO-based fluxes was 0.4xl0^(-3)-8.2xl0^(-3) g/(cm^2 centre tos) and the mass-transfer coefficient of phosphorus in bulk steel was 0.025-0.04 cm/s.
