Phosphorus Distribution Ratio Research Articles

A new steelmaking process using red mud as a fluorine-free flux: Promoting phosphorus removal and iron recovery

Bayer red mud, one of the most challenging solid wastes in the aluminum industry, is anticipated to be suitable for large-scale disposal in alignment with the specific requirements of the steelmaking process. This study determined the melting characteristics of various red mud-based fluxes using a high-temperature in-situ analysis system. Furthermore, the feasibility of large-scale application and the potential for substituting CaF2 in the iron and steelmaking process were investigated through a 10-kg induction furnace test and a 160-ton converter industrial test. The results indicate that the hot metal temperature during the pre-phosphorus removal stage ranged from 1254°C to 1430°C. Initial slag formation occurred within 2–4 minutes of oxygen blowing. The average slag basicity was between 1.5 and 2.1. Early dephosphorization and the average phosphorus distribution ratios were 41.4 %-63.4 % and 30, respectively. The mechanism of red mud-based fluxes in the early stage of steelmaking was further elucidated, and the application process was designed. The new process reduces the cost of slag materials, realizes the large-scale disposal of red mud, establishes the connection for the sustainable development of the steel and aluminum industries.

Effect of CaO-MgO-FeO-SiO2-xNa2O Slag System on Converter Dephosphorization

Na2O is an alkaline oxide, which can significantly improve the dephosphorization ability of converter slag. The effect of Na2O on the dephosphorization of converter slag was analyzed with a high-temperature dephosphorization experiment in a MoSi2 resistance furnace. We found that the dephosphorization rate increased with the increase of (Na2O) in the dephosphorization slag. The elements of Ca, Si, O, and P in the dephosphorization slag are distributed in the same area, mainly in the form of phosphate minerals, such as Ca2SiO4·0.05Ca3(PO4)2 and 6Ca2SiO4·Ca3(PO4)2. After adding Na2O, part of the Na will replace the Ca in the phosphorus-containing phase to form Ca2SiO4·Ca2Na2(PO4)2. The industrial test showed that the average dephosphorization rate in the early stage of the test heats with the CaO-MgO-FeO-SiO2-0.5%Na2O slag system could reach 62.39%, which was 19.62% higher than that of the conventional heats. The average basicity of the final slag was 0.19% lower than that of the conventional heats, while w(P2O5) increased by 0.36%, and T.Fe decreased by 0.69%. The average consumption of the slagging materials was 35.93 kg/t, which was 7.24 kg/t less than that of the conventional heats. Through thermodynamic calculation, we found that with the increase of (Na2O), the phosphorus distribution ratio between slag and steel increased significantly, the area of the liquid phase zone of the slag system increased continuously, and the viscosity decreased continuously.

Development of Iron Recovery Technique from Steelmaking Slag by Reduction at High Temperature

In order to develop a new recycling process of steelmaking slag, reduction of (FetO) and (P2O5) in steelmaking slag at high temperature have been investigated. In this work, 50 kg-scale experiments which simulated rotary kiln were conducted to investigate the separation behavior between slag and metal. Main results are as follows. (1) Molten iron was tapped out from the experimental furnace under the condition that more than 86% iron was reduced. (2) Weight of reduced iron did not affect the undefined ratio of phosphorus. (3) Common logarithm of phosphorus distribution ratio (logLP), which was used as an index to explain the effect of slag composition, temperature and oxygen potential, correlates to the undefined phosphorus ratio. (4) In the experiments which simulated rotary kiln treatment, calculated phosphorus distribution ratio (LP) was smaller than that from experimental results. It can be said that the phosphorus transfer into the metallic phase decreased because the smaller interface between slag phase and metallic phase was obtained due to the slag/metal separation.

Ionic analysis of the effect of temperature on dephosphorization capacity of silicate slags

ABSTRACT In order to the improvement of steel quality and dephosphorization capacity, it is vital to realize the microscopic essence of dephosphorization reaction of the slags. In this work, the temperature dependence of phosphorus distribution ratio and phosphate capacity is discussed with respect to the structure characterized by Raman and MAS-NMR. As the temperature increases from 1550°C to 1600°C, the reduction of Q0(Si) and Q0(P) weakens the formation of the Si–O–Ca–O–P linkages that can stabilize the silicate and phosphate network, which is not conducive to the increase of phosphorus distribution ratio and phosphate capacity. Meanwhile, the slight reduction of NBO/T lowers the activity of O2−, resulting that the hybrid entropy of dephosphorization reaction at 1600°C being slightly greater than that at 1550°C, indicating that the dephosphorization reaction proceeds towards the reverse direction with the increase of temperature.

Evaluation of Phosphorus Enrichment Capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 Dephosphorization Slag Based on Ion‐Molecule Coexistence Theory

Herein, the phosphorus enrichment capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 dephosphorization slag is studied based on ion‐molecule coexistence theory (IMCT) and industrial experiment. The equilibrium mass percentages of structural units in dephosphorization slag have different degrees of linear relationship with the corresponding mass action concentrations N i . The calcium phosphate in dephosphorization slag has the greatest contribution to phosphorus distribution ratio and phosphate capacity, up to 99.99%, in which 3CaO·P2O5 has about 94.97%. Compared with the other 23 phosphorus distribution ratio and 7 phosphate capacity empirical models, IMCT model can accurately predict the phosphorus distribution ratio with the lowest average relative error of 3.70% and the second lowest standard deviation of 2.34%, and phosphate capacity with the lowest average relative error of 0.80% and the lowest standard deviation of 0.52%. At 1620–1640 °C, with increasing phosphorus enrichment contribution ratio of 2CaO·SiO2 in slag, the dephosphorization capacity of slag is greatly improved. The change trends of phosphorus enrichment capacity evaluation indexes of slag calculated based on IMCT are well consistent with the change trend of dephosphorization ratio of molten steel, indicating the IMCT calculation results can correctly predict the phosphorus enrichment capacity of dephosphorization slag in converter dephosphorization process.

A Novel Process Design and Industrial Practice of Single‐Slag Smelting in 120 t Converter

With the reduction of raw material quality and the improvement of user requirements, the cost of dephosphorization increases. Steel plants urgently need an efficient and economic dephosphorization process to support the production. To address this issue, first, the migration and distribution of phosphorus in the converter smelting process are described quantitatively. Based on the regular solution model, the influence of slag components and temperature on the dephosphorization capacity of steel slag is explored. Afterward, considering the phosphorus distribution ratio, melting point, and phosphorus capacity of slag, the advantages of the slag‐forming route with higher FeO content in rapid slag formation and dephosphorization are expounded. Based on the guidance of the slag‐forming route, the scheme of controlling oxygen lance position and charging is optimized, and a novel blowing control mode is proposed. Finally, industrial tests on a 120 t converter show that the optimized smelting mode significantly reduces the cost and improves the efficiency. As a result, the lime consumption used to smelt a ton of steel is reduced by 3.67 kg t−1, and the dephosphorization rate is still increased by about 3.07%.

Effects of Biodegradable Film Raw Material Particles on Soil Properties, Wheat Growth, and Nutrient Absorption and Transportation

Biodegradable plastic film is one of the effective ways to solve the problem of white pollution in agriculture. However, its impacts on soil-plant systems are not well documented. In order to provide a basis for the safety evaluation of large-scale application of biodegradable plastic film, pot experiments were conducted to investigate the effects of the types(H, S, and X) and doses(2.5, 10, and 40 g·kg-1) of biodegradable film raw material particles on the soil physiochemical properties, biological properties, growth, and nutrient absorption by wheat (Triticum aestivum L.). The results showed that three types of biodegradable film raw material particles significantly increased soil pH but had no significant effect on soil organic matter content; medium-high doses of H and low-medium doses of S plastic particles had a positive effect on soil nitrification and soil nitrogen availability, whereas X film particles had an inhibitory effect. H film particles increased soil available phosphorus content, and S and X had no significant effect. X film particles increased the content of soil available potassium, but S and H had no significant effect. The effects of three types of biodegradable raw material particles on soil enzyme activities varied with the types and doses of plastic film and enzyme types. With the increase in the doses of plastic film particles, the activities of three kinds of soil enzymes showed a downward trend. Except for the low and medium doses of the S treatment, the other treatments inhibited the growth of wheat, in which X film particles had the greatest inhibitory effect on the biomass of wheat roots, stems, leaves, and grain; with the increase in the doses of film particles, the inhibition effect of wheat biomass was more obvious. For wheat nutrients, the absorption of nitrogen was promoted at low doses and inhibited at high doses, and the three types of film particles inhibited the absorption of phosphorus and potassium. There were significant differences in the distribution ratio of nitrogen and phosphorus between the stems, leaves, and grains of wheat by all the film particles; however, there was no significant difference in the distribution ratio of potassium between those treatments. Correlation analysis showed that wheat biomass was the main factor affecting wheat nutrient accumulation.

Estimation of phosphorus distribution ratio at the end of blowing in BOF

In integrated steel plants, the removal of phosphorous normally takes place during the primary basic oxygen furnace (BOF) steelmaking process. Phosphorous is usually introduced to the integrated steelmaking process through blast furnace additions, such as iron ore, coke, sinter, and fluxes. Among the others parameters such as optimizing the charging system, oxygen supply system, oxygen lance parameters of the converter, the flux quality in combination with temperature process control can improve the BOF efficiency of Dephosphorization. Phosphorus partition ratio (LP) is usually used to evaluate the thermodynamic efficiency of the dephosphorization of slags with different compositions in steelmaking processes. However, this parameter is only useful in equilibrium conditions, and it is not accurate when used to evaluate slag efficiency in industrial processes. Because of this, the aim of this work was to study the phosphorus partition ratio estimated from the experimental results in real plant conditions of two different BOF steel plants and compare them with well-known published models. In the present study, data from two steel plants (further Plant A and Plant B) were evaluated applying Healy’s, Suito and Inoui’s, Zhang’s as well as Assis’s equations. The calculated values were compared against measured values.

Kinetic model of dephosphorization in the new double slag converter steelmaking process

ABSTRACT The kinetic investigation of the dephosphorization in the new double slag converter steelmaking process was carried out based on the coupled reactions model combining with a heat balance temperature model for the 220-ton industrial experiment. The calculated results of [%C], [%Si], [%P] in the hot metal, and the slag compositions are in good agreement with the experimental results. When the heat balance temperature model is applied, the P prediction results are better rather than those predicted by using the fixed temperatures. The calculated phosphorus distribution ratio increases with the refining time, while the phosphate capacity shows a downward trend due to the decrease in slag basicity and the increase in temperature. The rate-controlling step of the dephosphorization is determined to be the mixed control of the mass transfer of P in the hot metal and P2O5 in the slag. As the initial Si concentration is increased, the interfacial oxygen activity required for starting the dephosphorization is increased, leading to the delay of the dephosphorization start time.

Study on Slag Forming Route of Dephosphorization in Combined Blown Converter

In order to achieve the purpose of high-efficiency dephosphorization by single-slag method during the combined blown converter steelmaking process, the CaO-SiO2-FetO-MgO-MnO-P2O5 slag system was taken as the research object, and the slag-forming route of dephosphorization was studied. The effects of slag compositions on the liquidus and the contour map of phosphorus distribution ratios (recorded as Lp) were calculated by thermodynamics software FactSage, and then the theoretic slag-forming route of dephosphorization was obtained. The effects of slag compositions on dephosphorization rate and Lp were studied by a high-temperature experiment. Based on the results of the theoretic calculation and high-temperature experiment, the actual slag-forming route of dephosphorization by the single-slag process in the combined blown converter was obtained: The initial slag composition should be around 15.0%CaO-44.0%SiO2-41.0%FetO. The composition of high-efficiency dephosphorization slag should be around 50.8%CaO-24.2%SiO2-25%FetO. The final slag composition should be around 65.6%CaO-28.3%SiO2-6.1%FetO. After using the actual slag-forming route in the production, the dephosphorization rate was increased by 3.6%, and the consumption of slagging materials was reduced by 3.78 kg/t.

Dephosphorization in Double Slag Converter Steelmaking Process at Different Temperatures by Industrial Experiments

In the present work, the effect of dephosphorization endpoint temperature on the dephosphorization of hot metal was studied for the double slag converter steelmaking process under the conditions of low temperature and low basicity by the industrial experiments. In the temperature range of 1350–1450 °C, with an increasing dephosphorization endpoint temperature, the dephosphorization ratio and phosphorus distribution ratio first increase and then decrease. The phosphorus content in hot metal first decreases and then increases at the end of dephosphorization. At the dephosphorization temperature range of 1385–1410 °C, the dephosphorization ratio is higher than 55%, the P2O5 content in the dephosphorization slag is 3.93–4.17%, the logLP value is 1.76–2.09, the value of PCOP-C of the selective oxidation reaction of carbon and phosphorus is 53–80 Pa, and the aFeO value is 0.284–0.312. The path of phosphorus in hot metal entering the P-rich phase of dephosphorization slag can be reasonably inferred as: hot metal → Fe-rich phase → P-rich phase. Under the present industrial experimental conditions, the dephosphorization and rephosphorization reactions are in dynamic equilibrium at 1413 °C. Considering the experimental results and thermodynamic calculation results of industrial experiments by the double slag dephosphorization process, the optimal temperature range for intermediate deslagging is about 1400–1420 °C.

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

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.

A Review of Multi-phase Slag Refining for Dephosphorization in the Steelmaking Process

Dephosphorization has always been a challenging task in the steelmaking process. In the traditional studies, CaO-based steelmaking slag was usually treated as a homogeneous liquid phase to analyze the dephosphorization equilibrium between molten slag and hot metal (slag/metal). In fact, the slag shows a coexisting state of both liquid and solid at steelmaking temperature. In recent years, multi-phase slag refining has been proposed and proved to be an efficient technique to improve the utilization of solid lime and the dephosphorization efficiency in steelmaking practices. The present review focuses on hot issues for the multi-phase slag refining, including the dissolution of solid lime to the molten slag, the formation of 2CaO·SiO2 and phosphorus-rich solid solution of 2CaO·SiO2-3CaO·P2O5, as well as the phosphorus distribution ratio between the solid and liquid phases in the multi-phase slag. In addition to the discussion on thermal and kinetic factors of dephosphorization, the necessity of further research is proposed on the dissolution behavior of phosphorus-rich solid solution and phosphorus redistribution in the slag of high temperature, high basicity and high FeO in the final stage of converter steelmaking. Then, a more applicable dynamic model of dephosphorization could be expected considering the equilibrium not only between molten slag and liquid metal but also among the phases of the multi-phase slag in steelmaking process. Furthermore, the modelling work is beneficial for the fine control of the BOF process and the development of intelligent manufacturing in steelmaking industry.

Effect of various components on the distribution of phosphorus in CaO–FeO–MgO–SiO2–MnO–TiO2–V2O5–P2O5 slag based on IMCT

ABSTRACT A thermodynamic calculation model of phosphorus distribution ratio between CaO–FeO–MgO–SiO2–MnO–TiO2–V2O5–P2O5 slags and molten metal has been developed based on the ion and molecule coexistence theory (IMCT). The calculated phosphorus distribution ratio shows a good agreement with the measured ones by the data of industrial trial, which proves the reliability of this model. Therefore, the model is used to study the effects of TiO2, V2O5, slag basicity, FeO, MgO and MnO on phosphorus distribution. The results illustrate that the effects on phosphorus distribution from V2O5 and TiO2 are non-negligible and they are almost the same, slag basicity and FeO have the most significant effects on phosphorus distribution, while MgO and MnO have the least.

Behavior of phosphorus enrichment in dephosphorization slag at low temperature and low basicity

At low basicity and low temperature, the dephosphorization behavior and phosphorus distribution ratio (LP) between slag and molten steel in the double slag and remaining slag process were studied with a 180 t basic oxygen furnace industrial experiment. The dephosphorization slags with different basicities were quantitatively analyzed. At the lower basicity range of 0.9–2.59, both LP and dephosphorization ratio were increased as the basicity of dephosphorization slag increased. Dephosphorization slag consisted of dark gray P-rich, light gray liquid slag, and white Fe-rich phases. With increasing basicity, not only did the morphologies of different phases in the dephosphorization slag change greatly, but the area fractions and P2O5 content of the P-rich phase also increased. The transfer route of P during dephosphorization can be deduced as hot metal → liquid slag phase + Fe-rich phase → P-rich phase.

Distribution Behavior of Phosphorus in 2CaO·SiO2-3CaO·P2O5 Solid Solution Phase and Liquid Slag Phase

In this paper, the CaO-SiO2-FetO-P2O5 dephosphorization slag system during the premier and middle stage of the converter process was studied, the effect of slag composition on the distribution ratio and activity coefficient of P in the n·2CaO·SiO2-3CaO·P2O5 (recorded as nC2S-C3P) solid solution phase and liquid slag phase in the slag system was studied used by the high temperature experiment in laboratory, the theoretical calculation of thermodynamics, and the scanning electron microscope and the energy dispersive spectrometer (recorded as SEM/EDS). The research results show that when the FeO content in the liquid slag increases from 32.21% to 50.31%, the distribution ratio of phosphorus (recorded as LP) in the liquid slag phase increases by 3.34 times. When the binary basicity in the liquid slag increases from 1.08 to 1.64, the LP in the liquid slag phase decreases by 94.21%. In the initial slag, when the binary basicity increases from 2.0 to 3.5, the LP decreases by 70.07%. When FeO content increases from 38.00% to 51.92%, the LP increases by 6.15 times. When P2O5 content increases from 3.00% to 9.00%, the LP increased by 10.67 times. When the FeO content in the liquid slag increases from 32.21% to 50.31%, the activity coefficient of P2O5 in the liquid slag phase (recorded as γP2O5(L)) increases by 54.33 times. When the binary basicity in the liquid slag increases from 1.08 to 1.64, γP2O5(L) decreases by 99.38%. When the binary basicity increases from 2.0 to 3.5, the activity coefficient of P2O5 in the solid solution phase (recorded as γP2O5(SS)) in the solid solution phase decreases by 98.85%. When P2O5 content increases from 3.00% to 9.00%, γP2O5(SS) increases by 1.14 times. When the binary basicity decreases from 3.5 to 2.0, n decreases from 0.438 to 0.404. When the FeO content increases from 38.00% to 51.92%, n decreases from 0.477 to 0.319. When the P2O5 content increases from 3.00% to 9.00%, n decreases from 0.432 to 0.164. The decrease of binary basicity and the increase of FeO and P2O5 content in the initial slag can reduce the value of n and enrich more phosphorus in the solid solution phase. The results can not only provide a theoretical basis for industrial production, but also lay a theoretical foundation for finding more effective dephosphorization methods.

Effect of basicity on dephosphorization of hot metal with a low basicity slag at 1653 K

ABSTRACT This research aims to investigate the influence of the slag basicity from 1.40 to 1.83 on dephosphorization of the hot metal with a CaO–FeO–SiO2–MgO–Al2O3 molten slag at the low temperature of 1653 K. The results indicated that the dephosphorization ratio was increased with the increase of basicity. Even at the low basicities of 1.73 and 1.83, the dephosphorization ratios can be as high as 77.3 and 80.7%, respectively. With the increase of basicity, the contents of P2O5 and total iron in the slag were increased, whereas the content of MnO was decreased. The distribution ratio of phosphorus was expressed as . The values calculated by the present method are well consistent with the measurement values. Besides, the dark grey phase B and the light grey phase D could be considered as the phosphorus-rich phases containing C2S solid particles.

Effects of calcium ferrite slag on dephosphorization of hot metal during pretreatment in the BOF converter

A study was carried out to examine effects of calcium ferrite slag on dephosphorization of hot metal in the steelmaking BOF, with aims to pick up the speed of slag-forming, increase the slag dumping rate. Laboratory tests using a resistance furnace were performed to examine melting characteristics of calcium ferrite pellets, designed with the optimum ratio of iron oxides (total Fe 55%) to CaO of 3:1. The pellets were put in crucibles with furnace temperature held in the range of 1250–1350 °C for 10 min. The results showed that the melting of pellets was nearly completed at 1250°C and main mineral phases, detected by XRD, in the melted samples were CaO•Fe2O3 and 2CaO•Fe2O3. Based on results of the laboratory tests, experiments of full scale were performed using a converter of 120t, charging the hot metal with C 3.46–6.81%, Si 0.1–1.16%, Mn 0.12–0.30%, P 0.10–0.18%, S 0.017–0.13% and temperature of 1234–1430 °C. For the 13 test heats with 6 min of oxygen blowing, the rate of dephosphorization and phosphorus distribution ratio reached to 50–60% and 55.9, respectively, when the calcium ferrite pellets were charged. Averaged slag basicity 1.5–2.0, slag melting point 1280–1310℃, slag viscosity 0.5 pa.s were obtained for the BOF heats adding the calcium ferrite pellet, which ensured the slag foaming height controlled at 2.5–3.0 m during the early stages of the blow. Using above smelting process has increased the rate of slag dumping controlled at 50–70% and enhanced the rate of hot metal dephosphorization over 90%.

A phosphorus distribution prediction model for CaO–SiO2–MgO–FeO–Fe2O3–Al2O3–P2O5 slags based on the IMCT

ABSTRACT A thermodynamic model for predicting the phosphorus distribution ratio L P of CaO–SiO2–MgO–FeO–Fe2O3–Al2O3–P2O5 slags was developed by considering the mass action concentration of ion couples or structural units in slags based on the ion-molecule coexistence theory (IMCT) and is referred to as the IMCT-L P model. Compared with the equilibrium mole number or mass percentage of the slag components, the mass action concentration for structural units of CaO–SiO2–MgO–FeO–Fe2O3–Al2O3–P2O5 slags used in HIsmelt smelting reduction ironmaking can characterize the reaction ability of the components. The mass action concentration of the iron oxides may characterize the oxidizing ability of the slag. The dephosphorization reactions in the HIsmelt smelting reduction vessel are jointly controlled by basic oxides and the oxidizing ability of the slag. The IMCT model can not only accurately predict the total phosphorus distribution ratio of metallurgical slags but also forecast the respective phosphorus distribution ratio of basic oxides in the slag, i.e. the dephosphorization contribution rates of 3CaO·P2O5, 4CaO·P2O5 and 2CaO·P2O5 were 99.7%, 0.227% and 0.033%, respectively. Moreover, to more conveniently predict the phosphorus distribution ratio, the empirical formulas of the phosphorus distribution ratio considering slag composition and temperature were determined by mathematical regression.

An Improved CBR Model Based on Mechanistic Model Similarity for Predicting End Phosphorus Content in Dephosphorization Converter

There has been a lack of reliable online measuring equipment on end phosphorus content in dedicated dephosphorization converter, which leads to the low control accuracy of end phosphorus content. A Case‐based Reasoning (CBR) method based on mechanistic model similarity is proposed to predict the end phosphorus content in dephosphorization converter. The correlation between the influencing factors and target as well as the similarity between influencing factors of different cases are considered comprehensively in the proposed method. Firstly, the mechanistic model of end phosphorus content in dephosphorization converter is established by using the slag phosphorus distribution ratio and Matter Conservation. Then, the similarity calculation equation of mechanistic model is designed. Lastly, the prediction result is obtained by bringing the mechanistic model of end phosphorus content into the designed similarity calculation method. CBR method based on mechanistic model similarity (CBR‐MM), mechanistic model, Back Propagation Neural Network (BPNN), CBR based on Euclidean Distance similarity (CBR‐ED), and CBR based on Grey Distance similarity (CBR‐GD) are used to predict end phosphorus content by applying practical production data. The result shows CBR‐MM has higher prediction accuracy compared to other methods.