scholarly journals Mechanism of Phosphorus Enrichment in Dephosphorization Slag Produced Using the Technology of Integrating Dephosphorization and Decarburization

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 216
Author(s):  
Haimeng Xue ◽  
Jie Li ◽  
Yunjin Xia ◽  
Yong Wan ◽  
Liangjun Chen ◽  
...  
Keyword(s):  
Solid Solution ◽  
Distribution Ratio ◽  
Thermodynamic Calculation ◽  
Slag Composition ◽  
Slag Basicity ◽  
Hot Metal ◽  
Phosphorus Enrichment ◽  
Phosphorus Distribution ◽  
Dephosphorization Slag ◽  
Phosphorus Distribution Ratio

In order to better understand and develop the technology of integrating dephosphorization and decarburization in a single converter (abbreviated as IDDSC), the relevant thermodynamic issues were discussed by calculation. Based on the thermodynamic calculation, the bridges between the phosphorus distribution ratio, temperature, and slag composition were constructed. Besides, the connections between the dephosphorization behavior and the microstructure of slag were also established by investigating four heats of hot metal smelt using IDDSC technology. As a result, the mechanism of phosphorus enrichment in the dephosphorization slag was revealed. Also, the results show that the dephosphorization efficiency increases gradually with increasing slag basicity. While the dephosphorization efficiency increases first and then decreases with the increase of FeO content in slag. There is a competition relationship between P2O5 and FeO in reacting with CaO and SiO2. When CaO/FeO is relatively high, not enough FeO is provided. Thus P2O5 is in priority to react with CaO and SiO2 through [3n + 2](CaO) + 2SiO2 + n(P2O5) = n(3CaO·P2O5)-2CaO·SiO2(s), generating P2O5-rich nC2S-C3P solid solution which promotes the removal of [P] from the hot metal. When CaO/FeO is relatively low, FeO competes over P2O5 in reacting with CaO and SiO2 through a(CaO) + b(SiO2) + c(FeO) = aCaO·bSiO2·cFeO(s), generating CaFeSiO4 instead of P2O5-rich solid solution. As a consequence, the slag with low CaO/FeO shows a poor dephosphorization ability.

Phosphorus Distribution Equilibrium between CaO-FeO*-SiO2-P2O5(15%)-CaF2(B2O3) Slag System and Carbon-Saturated Hot Metal at 1573K

2011 ◽  
Vol 402 ◽  
pp. 227-234
Author(s):  
Jin Dong Zhou ◽  
Xue Gong Bi ◽  
Zhi Cheng Huang ◽  
Zhi Jun Wen ◽  
Fu Yang ◽  
...  
Keyword(s):  
Distribution Ratio ◽  
Equilibrium Condition ◽  
Slag System ◽  
Dramatic Reduction ◽  
Hot Metal ◽  
Phosphorus Distribution ◽  
High Phosphorus ◽  
Solid Iron ◽  
The One ◽  
Phosphorus Distribution Ratio

In order to understand the equilibrium condition of phosphorus between slag and hot metal saturated with carbon in the high phosphorus hot metal dephosphorization process, the dephosphorization capacity of CaO-FeO*-SiO2-P2O5(15%) -CaF2(B2O3) slag system at 1573 K was studied, by applying the method that phosphorus distribution ratio between slag and solid iron was firstly measured and the one between slag and hot metal was then calculated. The results showed that phosphorus distribution ratio decreased with increase in basicity of CaO/(SiO2 +P2O5), a proper increase in SiO2 content is helpful to the absorption of phosphorus into slag, an increase in FeO* content from 10.52% to 13.40% resulted in a dramatic reduction of phosphorus distribution ratio from 126.43 to 33.25, by completely substituting CaF2 with B2O3 at 2.5 of basicity and 0.07 of B2O3/CaO ratio not only was acquired a high phosphorus distribution ratio of 171, but also was decreased pollution to the environment.

Thermodynamic Modelling of Phosphorus in Steelmaking Slags

2013 ◽  
Vol 32 (3) ◽  
pp. 237-246 ◽  
Author(s):  
Chunlin Chen ◽  
Ling Zhang ◽  
Jean Lehmann
Keyword(s):  
Liquid Iron ◽  
Distribution Ratio ◽  
Operating Conditions ◽  
Model Parameters ◽  
Steelmaking Slag ◽  
Maximum Point ◽  
Phosphorus Distribution ◽  
Steelmaking Slags ◽  
Model Database ◽  
Phosphorus Distribution Ratio

AbstractThe published phase diagrams of some key P2O5-containing systems which are relevant to the steelmaking slag and the available experimental data on phosphorus partitioning between liquid iron and slags consisting of SiO2-Al2O3-Fe2O3-FeO-MnO-MgO-CaO-Na2O have been reviewed and assessed. A set of data under carefully controlled experimental conditions, which was considered to be more reliable based on the assessment, was selected for optimising the generalised central atom (GCA) model parameters of phosphorus-containing slag systems. The developed model database is proved to be able to represent the liquidus temperature of some key P2O5-containing systems and the phosphorus distribution ratio between the steelmaking slags and liquid iron reasonably well. With the developed GCA model database, the dephosphorization reaction in the steelmaking process was modelled under various operating conditions such as slag chemistry and temperature. The results show that the phosphorus distribution ratio between the slags and liquid iron displays a maximum point with variation of the FeOx content in the slag. It also shows that the phosphorus deportment to the slag is favored by decreasing the operating temperature and MgO content, and increasing the CaO/SiO2 ratio in the slag. Comparison with the model of the phosphorus distribution data from a commercial BOS furnace shows that operating conditions do not permit to reach P equilibrium contents. The dis-equilibrium degree of P was found to be increased with increasing slag viscosities.

Dephosphorization Ability Estimation of FetO-Rich Demanganization Slag during Hot Metal Pre-Treatment

2012 ◽  
Vol 560-561 ◽  
pp. 1027-1034
Author(s):  
Cheng Yi Zhu ◽  
Jun Liu ◽  
Guang Qiang Li ◽  
Zhao Ping Chen
Keyword(s):  
Phosphorus Content ◽  
Hot Metal ◽  
Phosphorus Distribution ◽  
Equilibrium Quotient ◽  
Multiple Regression Method ◽  
Solid Iron ◽  
Thermodynamic Conditions ◽  
Pre Treatment ◽  
Phosphorus Distribution Ratio ◽  
Pure Argon Atmosphere

In order to find out the optimum thermodynamic conditions for hot metal dephosphorization and predict phosphorus content after demanganization pretreatment, thermodynamic equilibrium experiments between CaO-FetO-SiO2-MnO-P2O5 slag and silver/solid iron were carried out in an iron crucible at different temperature under pure argon atmosphere in an electric resistant furnace. The results indicate that phosphorus distribution ratios increase with an increase of basicity in the slag at the experiment temperature, and then they decrease with an increase of basicity at 1573K and 1623K. The phosphorus distribution ratios decrease with an increase of FetO content in the slag at 1573K, while they increase with an increase of FetO content in the slag and then decrease with an increase of FetO content in the slag at 1623K. The results indicate that the maximum phosphorus distribution ratio between slag and hot metal is 92.4 when basicity of the slag is 1.7 and FetO content in slag is 49.75 mass% at 1623K, and the correspondent phosphorus content in the carbon saturated iron is 0.019mass%. Dephosphorization is easier under low temperature. The equilibrium quotient of phosphorus obtained in the present work is formulated as a function of slag compositions and temperature using the multiple regression method which is used to predict phosphorus content equilibrium with the demanganization slag and optimum conditions needed for ideal phosphorus contents in demanganization pretreatment.

scholarly journals Effect of the Fe2O3 Addition Amount on Dephosphorization of Hot Metal with Low Basicity Slag by High-Temperature Laboratorial Experiments

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 417
Author(s):  
Wenkui Yang ◽  
Jian Yang ◽  
Yanqiu Shi ◽  
Zhijun Yang ◽  
Fubin Gao ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Theoretical Calculation ◽  
Oxygen Potential ◽  
Oxygen Activity ◽  
Hot Metal ◽  
Rich Phase ◽  
Addition Amount

In this paper, the influence of the Fe2O3 addition amount on the dephosphorization of hot metal at 1623 K with the slag of the low basicity (CaO/SiO2) of about 1.5 was investigated by using high-temperature laboratorial experiments. With increasing the Fe2O3 addition amount from 5 to 30 g, the contents of [C], [Si], [Mn] and [P] in the hot metal at the end of dephosphorization are decreased and the corresponding removal ratios increase. In dephosphorization slags, the phosphorus mainly exists in the form of the nCa2SiO4–Ca3(PO4)2 solid solution in the phosphorus-rich phase and the value of coefficient n decreases from 20 to 1. Furthermore, the oxygen potential and activity at the interface between the slag and hot metal are increased. When the oxygen potential and the oxygen activity at the interface are greater than 0.72 × 10−12 and 7.1 × 10−3, respectively, the dephosphorization ratio begins to increase rapidly. When the Fe2O3 addition amount is increased to 30 g, the ratio of the Fe2O3 addition amount to theoretical calculation consumption is around 175%, and the dephosphorization ratio reaches the highest value of 83.3%.

scholarly journals Effect of 2CaO·SiO2 particles addition on dephosphorization behavior

2020 ◽  
Vol 39 (1) ◽  
pp. 219-227
Author(s):  
Aijun Deng ◽  
Yunjin Xia ◽  
Jie Li ◽  
Dingdong Fan
Keyword(s):  
Liquid Slag ◽  
Solid Phase ◽  
Solid Particles ◽  
Hot Metal ◽  
Liquid Silicate ◽  
Phase Complex ◽  
Dephosphorization Slag ◽  
Stage 1 ◽  
Two Stages ◽  
Complex Liquid

AbstractThe effect of the addition of 2CaO·SiO2 solid particles on dephosphorization behavior in carbon-saturated hot metal was investigated. The research results showed that the addition of 2CaO·SiO2 particles have little influence on desilication and demanganization, and the removal of [Si] and [Mn] occurred in the first 5 min with different conditions where the contents of 2CaO·SiO2 particles addition for the conditions 1, 2, 3, 4, and 5 are 0, 2.2, 6.4, 8.6, and 13.0 g, respectively. The final dephosphorization ratios for the conditions 1, 2, 3, 4, and 5 are 61.2%, 66.9%, 79.6%, 63.0%, and 78.1%, respectively. The dephosphorization ratio decreases with the increase of 2CaO·SiO2 particles in the first 3 min. The reason for this is that the dephosphorization process between hot metal and slag containing C2S phase consisted of two stages: Stage 1, [P] transfers from hot metal to liquid slag and Stage 2, the dephosphorization production (3CaO·P2O5) in liquid slag reacts with 2CaO·SiO2 to form C2S–C3P solid solution. The increase of 2CaO·SiO2 particles increases the viscosity of slag and weakens the dephosphorization ability of the stage 1. The SEM and XRD analyses show that the phase of dephosphorization slag with the addition of different 2CaO·SiO2 particles is composed of white RO phase, complex liquid silicate phase, and black solid phase (C2S or C2S–C3P). Because the contents of C2S–C3P and 2CaO·SiO2 in slag and the dephosphorization ability of the two stages are different, the dephosphorization ability with different conditions is different.

Sign in / Sign up

Export Citation Format

Share Document