Effect of Al₂O₃ on the Melting, Viscosity, and Phosphorus Distribution of CaO–SiO₂–Fe₂O₃–P₂O₅ Slag System

Abstract

An investigation is conducted to study the effect of Al2O3 on the melting, viscosity, and phosphorus distribution of CaO–SiO2–Fe2O3–P2O5 slag system by using Single Hot Thermocouple Technique and rotating cylinder viscometer. The results show that with the addition of Al2O3 content, the melting temperature range of slag system is first reduced and then increased, as the added Al2O3 may react with CaO to form different compounds with varied melting points. The slag viscosity increases with the addition of Al2O3 content, due to the fact that the polymerization degree of the melt slag is getting increased. Besides, the addition of Al2O3 can improve the mass percentage of P2O5 in the solid phase, but it may reduce the dephosphorization capacity of the slag due to the reduction of the total solid phase solution (2CaO · SiO2–n3CaO · P2O5) precipitation. The results of this study can elucidate the effect of Al2O3 on the property of dephosphorization slag and provide guidelines for the new slag design to achieve a better hot metal dephosphorization efficiency.

Study on Slag Forming Route of Dephosphorization in Combined Blown Converter

“…2P + 5/3Fe 2 O 3 = 10/3Fe + P 2 O 5 (5) The reaction of oxidation of element Mn is shown in Equation ( 6):…”

“…Many scholars have studied the effect of slag composition and temperature on the dephosphorization efficiency under different conditions used by the methods such as theoretic calculation, high-temperature experiment and industrial test [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Some scholars have carried out research work on the slag-forming system and route of the converter process.…”

Microstructure and Viscosity of Dephosphorization Slag in New Double Slag Converter Steelmaking Process

“…However, the increase of Al 2 O 3 and the decrease of FeO content in slag can easily reduce the total amount of (Q 0 + Q 1 ) structure units. 7,8,22) Therefore, the total area fraction of (Q 0 + Q 1 ) structure units decreases with the increase in the dephosphorization temperature. The value of NBO/Si decreases with increasing the dephosphorization temperature, which further indicates that the DOP of the dephosphorization slag increases.…”

“…The increase of basicity and FeO content, as well as the decrease of Al 2 O 3 content in the slag can reduce the DOP of the slag, thus reducing the slag viscosity. [21][22][23] Therefore, when the temperature is higher than 1 723 K, the viscosities of different slags increase with increasing the end temperature of dephosphorization. When the temperature is lower than 1 723 K, all the dephosphorization slags are in a state of solid-liquid coexistence.…”

Effect of Al 2 O 3 on viscosity and structure of CaO–SiO 2 –FeO t –(Al 2 O 3 )–BaO slag

“…The phosphorus content of these domestic iron ore is high, leading to the increase of CaO consumption and the difficulty of CaO melting. CaF 2 has been employed as a slag agent to reduce the slag viscosity and promote the melting of CaO-based slag [1]. However, the CaF 2 is gradually limited because it can introduce severe environmental pollution.…”