In order to meet the requirements for environmental protection and achieve sustainable development for the steel industry, Baosteel＇ s secondary resources should be utilized in production. Hot metal dephosphorizing f...In order to meet the requirements for environmental protection and achieve sustainable development for the steel industry, Baosteel＇ s secondary resources should be utilized in production. Hot metal dephosphorizing factors are analyzed and the practice of a dephosphorizing agent for molten iron pretreatment with LT dust and BOF slag is introduced. Experimental results show that LT dust and BOF slag can be substituted for traditional raw materials, such as sinter and quicklime, etc in molten iron dephosphorization. The proper addition of LT dust or BOF slag and the proper control over basic agents, oxidizing agents and fluxes can achieve the same effect as traditional dephosphorizing agents. BaO can reduce the activity of P2O5 and form stable dephosphorizing products. Using a BaO dephosphorizing agent as a kind of harmless dephosphorizing agent will be one of the trends of molten iron dephosphorization.展开更多
With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be ...With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be used in ironmaking process due to its special structure.A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce phosphorus.The results showed that the powdery reduced iron produced contained 92.31%iron and 0.1%phosphorus,and the iron recovery was 92.65%under optimum reduction condition,which is suitable for following steelmaking.The apatite will be reduced under long reduction time and a large reducing gas flow rate,resulting in more phosphorus found in the metallic iron.Increasing the hydrogen–carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic structure.Careful adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.展开更多
The dissolution behaviors of lime,limestone,and core–shell structured lime,as well as their effects on dephosphorization behavior were studied.The results show that the slow dissolution of lime in converter slag is m...The dissolution behaviors of lime,limestone,and core–shell structured lime,as well as their effects on dephosphorization behavior were studied.The results show that the slow dissolution of lime in converter slag is mainly attributed to the calcium silicate layer at the lime/slag interface.CO_(2)generated by CaCO_(3)decomposition can destroy the calcium silicate layer,and thus accelerates the dissolution of limestone and core–shell structured lime.However,in the initial stage,a large amount of CO_(2)emission generated by limestone decomposition results in the poor contact between molten slag and limestone,and the dissolution rate is slower in the test of limestone than that of lime.For core–shell structured lime,the initial dissolution rate is not affected due to the lime surface,and is accelerated by the appropriate CO_(2)emission.Rapid CaO pickup in molten slag by fast dissolution of the lime sample can remarkably accelerate the dephosphorization reaction.Because of the fastest dissolution rate,the core–shell structured lime slagging mode shows the most promising prospects for the efficient dephosphorization.展开更多
It is shown by the the law of mass action in combination with the coexistence theory of slag structure that KMn n =NMno /(NFeo [%Mn] does not change with basicities and maintains constant at constant temperature; the...It is shown by the the law of mass action in combination with the coexistence theory of slag structure that KMn n =NMno /(NFeo [%Mn] does not change with basicities and maintains constant at constant temperature; the oxidizing capabilities of multicomponent slag systems containing CaO, MgO etc., can be expressed by NFe tO =NFeO + 6NFe2 O3 + 8NFe3O4; the desulfurizing capabilities of various basic oxides for multicomponent slag systems can be calculated by Ls=8(KCaSNCaO+KMgsNMgo +KFeSNFeO)∑n/[%O]; the dephosphorizing capabili- ties of CaO-MgO-FeO-FeO O3-P2 O5 as well as CaO-FeO-Fe2 O3-A12 O3-P2 O5 molten slags expressed respectively by Lpo=(%P2O5)/[P]2 = 141.94[%O]5∑nK00(1 + K5N2Cao + K6N3CaO + K7N4CaO + K8N2MgO + K9N3MgO + K10N3FeO + K11N4Feo); LPO=(%P2O5)/[P]2= 141.94[%O]5∑nK00(1 + K10N2CaO+ K11N3CaO+ K12N4CaO + K13N3FeO + K14N4FeO) have good agreement with practical values.展开更多
The reverse flotation separation performance and mechanism of hematite and cellophane in the presence of RFP-138, a newly synthesized dephosphorization collector, were studied. Reverse flotation tests on monominerals ...The reverse flotation separation performance and mechanism of hematite and cellophane in the presence of RFP-138, a newly synthesized dephosphorization collector, were studied. Reverse flotation tests on monominerals and artificially mixed minerals of hematite and collophanite show that, this anionic collector performs excellently in reducing the phosphorus content in hematite. It can decrease the content of P in artificially mixed minerals from 1.05% to 0.12% and achieve the TFe recovery rate of 91.30%. The chemical behavior of solution and infrared spectra of RFP-138 were investigated to explore the selective collecting mechanism of RFP-138 to these two minerals.展开更多
It is found that strong basic oxides including Li2O,Na2O,K2O and BaO,which are used to replace a part of CaO in CaO-based fluxes,can lower the melting point and the viscosity and enhance the dephosphorizing ability. T...It is found that strong basic oxides including Li2O,Na2O,K2O and BaO,which are used to replace a part of CaO in CaO-based fluxes,can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li2O to CaO based fluxes was recommended.展开更多
It is found that strong basic oxides including Li 2O, Na 2O, K 2O and BaO, which are used to replace a part of CaO in CaO based fluxes, can lower the melting point and the viscosity and enhance the dephosphorizing...It is found that strong basic oxides including Li 2O, Na 2O, K 2O and BaO, which are used to replace a part of CaO in CaO based fluxes, can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li 2O to CaO based fluxes was recommended.展开更多
The selective HCl leaching method was used to remove phosphorus from high phosphorus iron ores. The hydroxyapatite in high phosphorus iron ores was converted into soluble phosphate during the process of HCl leaching. ...The selective HCl leaching method was used to remove phosphorus from high phosphorus iron ores. The hydroxyapatite in high phosphorus iron ores was converted into soluble phosphate during the process of HCl leaching. The effects of reaction time,particle size,hydrochloric acid concentration,reaction temperature,liquid-solid ratio and stirring strength on the dephosphorization ratio were studied. The results showed that the dephosphorization ratio can exceed 98% under the conditions of reaction time 30-45 min,particle size 0.147 mm,hydrochloric acid concentration 2.5 mol/L,reaction temperature 25 ℃,liquid-solid ratio 5：1 and stirring strength 5.02-12.76 s-1. After dephosphorization reaction,the content of phosphorus in iron ore complied completely with the requirements of steel production.展开更多
A study on the production of low phosphorus steel by double slag operation in 210 t converter was carried out. A phosphorus content of less than 0.005% （mass percent） was obtained before tapping. About 80% phosphoru...A study on the production of low phosphorus steel by double slag operation in 210 t converter was carried out. A phosphorus content of less than 0.005% （mass percent） was obtained before tapping. About 80% phosphorus could be removed by the first slag after 5 min. High Fe^3＋ content and high basicity in the first slag were in favor of dephosphorization. On the other hand,Fe3＋ content had less effect on dephosphorization during second slag treatment. In the second slag period,the fraction of dephosphorization increased with the increase of basicity up to a basicity of 6. Further increase of basicity of the second slag had very little effect on dephosphorization. The tapping temperature had great impact on dephosphorization. It was impossible to get phosphorus less that 0.005% when the tapping temperature was higher than 1 943 K. The optimum operation conditions were suggested. On the basis of these conditions,the amount of the second slag and the effect of the remaining first slag were estimated.展开更多
The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperatur...The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.展开更多
To produce the steel with phosphorus less than 0. 007% （mass percent）, the double slag process has been optimized in basic oxygen furnace （BOF）. Dephosphorization and decarburization are performed in sequence in t...To produce the steel with phosphorus less than 0. 007% （mass percent）, the double slag process has been optimized in basic oxygen furnace （BOF）. Dephosphorization and decarburization are performed in sequence in the same converter. Deslagging is conducted twice, each at the end of dephosphorization and decarburization, by tilting the BOF. Production was tested in a 180 t BOF. Mass percent of phosphorus in steel at BOF blow end has been made to as low as 0. 004 2 % after optimizing operational parameters. Factors affecting dephosphorization performance were studied. Before intermediate deslagging, dephosphorization is determined by the mass transfer of phosphorus from metal/slag interface to bulk slag phase rather than equilibrium thermodynamic conditions. After intermediate deslag-ging, dephosphorization is deter/nined by the equilibriurn thermodynamic conditions such as slag composition and temperature.展开更多
To extract the valuable elements from the steel slag, a novel approach has been proposed by modification treatment to provide the stronger driving forces and accelerate the reduction. Three types of dephosphorization ...To extract the valuable elements from the steel slag, a novel approach has been proposed by modification treatment to provide the stronger driving forces and accelerate the reduction. Three types of dephosphorization steel slags were reduced using carbon-saturated iron bath to extract iron and phosphorus simultaneously. During the process of reduction, slag composition, temperature, and original P2O5 content were investigated respectively. Slag modification treatment, adding either silica or alumina to vary the slag composition, was proven to accelerate the reduction of dephosphorization slag. The equilibrium time can be shortened from 60 to 30 min. Slag modification also allowed the reduction reaction to occur at lower temperature. After slag modification, the original P2O5 content in slag presents a slight difference on reduction process. Almost half of the reduced phosphorus was vaporized within 5 and 20 min. As more and more FeO was reduced, CO gas generation decreased, and evaporation amount of phosphorus therefore decreases.展开更多
Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids wer...Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.展开更多
The steel slag in the decarburization converter is treated by the little water-spreading （ LWS ） and the heat-stewed （ HS ） methods , which is used as the furnace burden of the dephosphorization converter.The slag...The steel slag in the decarburization converter is treated by the little water-spreading （ LWS ） and the heat-stewed （ HS ） methods , which is used as the furnace burden of the dephosphorization converter.The slag characteristics by the LWS and the HS methods and its application effects as the furnace burden are researched.The results show the moisture content in the HS slag is higher than that of the LWS slag.There is higher total iron content in the HS and the LWS slags and almost same melting point.The dicalcium silicate content in the LWS slag is higher than that in the HS slag.The tricalcium silicate in the LWS slag is lower than that in the HS slag.There are a lot of calcium ferrite in the LWS and the HS slags , which is beneficial to dephosphorization and slag melting.The LWS and the HS slags are added to dephosphorization converter each charge by 3or 6t.The results show that the saving lime is 0.7-1.0tfor each charge.The petrographic constitute of final slag for the dephosphorization converter by adding the LWS and the HS slags is dicalcium silicate , RO phase and glass phase.There are a little calcium ferrite phase in the LWS slag , which is helpful to dephosphorization.So there are better dephosphorization effects for the LWS and HS slags.展开更多
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 oxy...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.展开更多
Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ra...Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99.35 % at iron ore-biomass mass ratio of 1 ： 0.6, reduction temperature of 1100℃, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron （DRI） has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89.11%, iron recovery rate of 83.47%, and phosphorus content of 0.28% can be obtained when ore fines with particle size of -10μm account for 78.15%.展开更多
High-phosphorus iron ore resource is considered a refractory iron ore because of its high-phosphorus content and complex ore phase structure. Therefore, the development of innovative technology to realize the efficien...High-phosphorus iron ore resource is considered a refractory iron ore because of its high-phosphorus content and complex ore phase structure. Therefore, the development of innovative technology to realize the efficient utilization of high-phosphorus iron ore resources is of theoretical and practical significance. Thus, a method for phosphorus removal by gasification in the hydrogen-rich sintering process was proposed. In this study, the reduction mechanism of phosphorus in hydrogen-rich sintering, as well as the reduction kinetics of apatite based on the non-isothermal kinetic method, was investigated. Results showed that, by increasing the reduction time from 20 to 60 min, the dephosphorization rate increased from 10.93%to 29.51%. With apatite reduction, the metal iron accumulates, and part of the reduced phosphorus gas is absorbed by the metal iron to form stable iron-phosphorus compounds, resulting in a significant reduction of the dephosphorization rate. Apatite reduction is mainly concentrated in the sintering and burning zones, and the reduced phosphorus gas moves downward along with flue gas under suction pressure and is condensed and adsorbed partly by the sintering bed when passing through the drying zone and over the wet zone. As a result, the dephosphorization rate is considerably reduced. Based on the Ozawa formula of the iso-conversion rate, the activation energy of apatite reduction is 80.42 kJ/mol. The mechanism function of apatite reduction is determined by a differential method (i.e., the Freeman-Carroll method) and an integral method (i.e., the Coats-Redfern method). The differential form of the equation is f(α)=2(1-α)^(1/2), and the integral form of the equation is G(α)=1-(1-α)^(1/2).展开更多
Mass transfer of phosphorus in high-phosphorus hot-metal refining was investigated using CaO-FetO-SiO2 slags at 1623 K. Based on a two-film theory kinetic model and experimental results, it was found that the overall ...Mass transfer of phosphorus in high-phosphorus hot-metal refining was investigated using CaO-FetO-SiO2 slags at 1623 K. Based on a two-film theory kinetic model and experimental results, it was found that the overall mass transfer coefficient, which includes the effects of mass transfer in both the slag phase and metal phase, is in the range of 0.0047 to 0.0240 cm/s. With the addition of a small amount of fluxing agents A1203 or Na20 into the slag, the overall mass transfer coefficient has an obvious increase. Silicon content in the hot metal also influences the overall mass transfer coefficient. The overall mass transfer coefficient in the lower [Si] heat is much higher than that in the higher [Si] heat. It is concluded that both fluxing agents and lower [Si] hot metal facilitate mass transfer of phosphorus in liquid phases. Fur- thermore, the addition of Na20 could also prevent rephosphorization at the end of the experiment.展开更多
The formation of solid solution combined with tricalcium phosphate and dicalcium silicate could promote a considerable removal of phosphorus from liquid slag to solid during hot metal dephosphorization,and thus the de...The formation of solid solution combined with tricalcium phosphate and dicalcium silicate could promote a considerable removal of phosphorus from liquid slag to solid during hot metal dephosphorization,and thus the dephosphorization by using multi phase fluxes could significantly decrease the consumption of lime. However,the reaction mechanism of multi phase fluxes has not been understood clearly.In the present study,the phase diagram for the CaO-SiO_2-FeO-P_2O_5 system has been measured with certain oxygen partial pressure at hot metal pretreatment temperature.Comparing with the CaO-SiO_2-FeO system,shrinkage of liquid phase area at higher FeO contents was observed at 1 673 K with oxygen partial pressure of 9.2×10^(-11) atm.展开更多
In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-ph...In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-phosphorus iron and ilmenite. The effect, which is related to basicity, reduction temperature, carbon-oxygen ratio and time of ventilated oxygen to iron recovery, dephosphorization rate, content of iron, phosphorus, sulfur and titanium in pig iron, was investigated in the experiment. The results show that an ideal outcome can be gained in condition of 6：4 ration on Mengqiao concentrate and Huimin iron ore, temperature of 1 500℃, basicity of 1.3, 1.0 on molar ration of carbon to oxygen, time of 10 min on blowing-oxygen. The outcome is that there is no foamy slag in generation, a good separation of slag and iron, iron recovery with 91.41%, content of phosphorus with 0.27% and tilanium content less than 0.001%, The atmosphere of strong oxidizing in the upper of reduction container and high potential of oxygen in the composition of slag in this technique bring phosphorus, titanium and silicon into slag, which ensures less content of impurity in pig iron.展开更多
文摘In order to meet the requirements for environmental protection and achieve sustainable development for the steel industry, Baosteel＇ s secondary resources should be utilized in production. Hot metal dephosphorizing factors are analyzed and the practice of a dephosphorizing agent for molten iron pretreatment with LT dust and BOF slag is introduced. Experimental results show that LT dust and BOF slag can be substituted for traditional raw materials, such as sinter and quicklime, etc in molten iron dephosphorization. The proper addition of LT dust or BOF slag and the proper control over basic agents, oxidizing agents and fluxes can achieve the same effect as traditional dephosphorizing agents. BaO can reduce the activity of P2O5 and form stable dephosphorizing products. Using a BaO dephosphorizing agent as a kind of harmless dephosphorizing agent will be one of the trends of molten iron dephosphorization.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFC2902400 and 2021YFC2902404)Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-21-027 and FRF-IDRY-22-018).
文摘With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron content.However,HPOH is very difficult to be used in ironmaking process due to its special structure.A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce phosphorus.The results showed that the powdery reduced iron produced contained 92.31%iron and 0.1%phosphorus,and the iron recovery was 92.65%under optimum reduction condition,which is suitable for following steelmaking.The apatite will be reduced under long reduction time and a large reducing gas flow rate,resulting in more phosphorus found in the metallic iron.Increasing the hydrogen–carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic structure.Careful adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.
基金gratefully acknowledge the support from National Natural Science Foundation of China(Nos.52274305,52374309 and 52004189)Project of Hubei Provincial Department of Science and Technology(No.2022BAA021)+2 种基金China Postdoctoral Science Foundation(Nos.2023T160210 and 2022M721109)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)Open Foundation of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(FMRUlab-25-05).
文摘The dissolution behaviors of lime,limestone,and core–shell structured lime,as well as their effects on dephosphorization behavior were studied.The results show that the slow dissolution of lime in converter slag is mainly attributed to the calcium silicate layer at the lime/slag interface.CO_(2)generated by CaCO_(3)decomposition can destroy the calcium silicate layer,and thus accelerates the dissolution of limestone and core–shell structured lime.However,in the initial stage,a large amount of CO_(2)emission generated by limestone decomposition results in the poor contact between molten slag and limestone,and the dissolution rate is slower in the test of limestone than that of lime.For core–shell structured lime,the initial dissolution rate is not affected due to the lime surface,and is accelerated by the appropriate CO_(2)emission.Rapid CaO pickup in molten slag by fast dissolution of the lime sample can remarkably accelerate the dephosphorization reaction.Because of the fastest dissolution rate,the core–shell structured lime slagging mode shows the most promising prospects for the efficient dephosphorization.
文摘It is shown by the the law of mass action in combination with the coexistence theory of slag structure that KMn n =NMno /(NFeo [%Mn] does not change with basicities and maintains constant at constant temperature; the oxidizing capabilities of multicomponent slag systems containing CaO, MgO etc., can be expressed by NFe tO =NFeO + 6NFe2 O3 + 8NFe3O4; the desulfurizing capabilities of various basic oxides for multicomponent slag systems can be calculated by Ls=8(KCaSNCaO+KMgsNMgo +KFeSNFeO)∑n/[%O]; the dephosphorizing capabili- ties of CaO-MgO-FeO-FeO O3-P2 O5 as well as CaO-FeO-Fe2 O3-A12 O3-P2 O5 molten slags expressed respectively by Lpo=(%P2O5)/[P]2 = 141.94[%O]5∑nK00(1 + K5N2Cao + K6N3CaO + K7N4CaO + K8N2MgO + K9N3MgO + K10N3FeO + K11N4Feo); LPO=(%P2O5)/[P]2= 141.94[%O]5∑nK00(1 + K10N2CaO+ K11N3CaO+ K12N4CaO + K13N3FeO + K14N4FeO) have good agreement with practical values.
基金Project (2010FJ3069) supported by Science and Technology Project of Hunan Province, China
文摘The reverse flotation separation performance and mechanism of hematite and cellophane in the presence of RFP-138, a newly synthesized dephosphorization collector, were studied. Reverse flotation tests on monominerals and artificially mixed minerals of hematite and collophanite show that, this anionic collector performs excellently in reducing the phosphorus content in hematite. It can decrease the content of P in artificially mixed minerals from 1.05% to 0.12% and achieve the TFe recovery rate of 91.30%. The chemical behavior of solution and infrared spectra of RFP-138 were investigated to explore the selective collecting mechanism of RFP-138 to these two minerals.
基金Item Sponsored by National Natural Science Foundation of China(59774015)
文摘It is found that strong basic oxides including Li2O,Na2O,K2O and BaO,which are used to replace a part of CaO in CaO-based fluxes,can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li2O to CaO based fluxes was recommended.
基金the support of Wong K C Education Foundation , Hong Kong
文摘It is found that strong basic oxides including Li 2O, Na 2O, K 2O and BaO, which are used to replace a part of CaO in CaO based fluxes, can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li 2O to CaO based fluxes was recommended.
基金Item Sponsored by Natural Science Foundation Project of CQ CSTC of China (2009BA7071)
文摘The selective HCl leaching method was used to remove phosphorus from high phosphorus iron ores. The hydroxyapatite in high phosphorus iron ores was converted into soluble phosphate during the process of HCl leaching. The effects of reaction time,particle size,hydrochloric acid concentration,reaction temperature,liquid-solid ratio and stirring strength on the dephosphorization ratio were studied. The results showed that the dephosphorization ratio can exceed 98% under the conditions of reaction time 30-45 min,particle size 0.147 mm,hydrochloric acid concentration 2.5 mol/L,reaction temperature 25 ℃,liquid-solid ratio 5：1 and stirring strength 5.02-12.76 s-1. After dephosphorization reaction,the content of phosphorus in iron ore complied completely with the requirements of steel production.
文摘A study on the production of low phosphorus steel by double slag operation in 210 t converter was carried out. A phosphorus content of less than 0.005% （mass percent） was obtained before tapping. About 80% phosphorus could be removed by the first slag after 5 min. High Fe^3＋ content and high basicity in the first slag were in favor of dephosphorization. On the other hand,Fe3＋ content had less effect on dephosphorization during second slag treatment. In the second slag period,the fraction of dephosphorization increased with the increase of basicity up to a basicity of 6. Further increase of basicity of the second slag had very little effect on dephosphorization. The tapping temperature had great impact on dephosphorization. It was impossible to get phosphorus less that 0.005% when the tapping temperature was higher than 1 943 K. The optimum operation conditions were suggested. On the basis of these conditions,the amount of the second slag and the effect of the remaining first slag were estimated.
基金the National Natural Science Foundation of China(Nos.51734005,51874071,and 51604063)the Fok Ying Tung Education Foundation for Young Teachers in the Higher Education Institutions of China(No.161045)+1 种基金the Liao Ning Revitalization Talents Program(No.XLYC1807111)the Fundamental Research Funds for the Central Universities of China(No.N180105030).
文摘The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.
文摘To produce the steel with phosphorus less than 0. 007% （mass percent）, the double slag process has been optimized in basic oxygen furnace （BOF）. Dephosphorization and decarburization are performed in sequence in the same converter. Deslagging is conducted twice, each at the end of dephosphorization and decarburization, by tilting the BOF. Production was tested in a 180 t BOF. Mass percent of phosphorus in steel at BOF blow end has been made to as low as 0. 004 2 % after optimizing operational parameters. Factors affecting dephosphorization performance were studied. Before intermediate deslagging, dephosphorization is determined by the mass transfer of phosphorus from metal/slag interface to bulk slag phase rather than equilibrium thermodynamic conditions. After intermediate deslag-ging, dephosphorization is deter/nined by the equilibriurn thermodynamic conditions such as slag composition and temperature.
基金Item Sponsored by National Natural Science Foundation of China(50904017)Fundamental Research Funds for Central Universities of China(100402016)Postdoctoral Science Foundation of China(2011M500823)
文摘To extract the valuable elements from the steel slag, a novel approach has been proposed by modification treatment to provide the stronger driving forces and accelerate the reduction. Three types of dephosphorization steel slags were reduced using carbon-saturated iron bath to extract iron and phosphorus simultaneously. During the process of reduction, slag composition, temperature, and original P2O5 content were investigated respectively. Slag modification treatment, adding either silica or alumina to vary the slag composition, was proven to accelerate the reduction of dephosphorization slag. The equilibrium time can be shortened from 60 to 30 min. Slag modification also allowed the reduction reaction to occur at lower temperature. After slag modification, the original P2O5 content in slag presents a slight difference on reduction process. Almost half of the reduced phosphorus was vaporized within 5 and 20 min. As more and more FeO was reduced, CO gas generation decreased, and evaporation amount of phosphorus therefore decreases.
基金Project (50321402) supported by the National Natural Science Foundation of China project(2004CB619204) supported by Major State Basic Research Development Program of China
文摘Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.
基金Item Sponsored by National Key Technology Research and Development Program in 11th Five-Year Plan of China ( 2006BAE03A00 )
文摘The steel slag in the decarburization converter is treated by the little water-spreading （ LWS ） and the heat-stewed （ HS ） methods , which is used as the furnace burden of the dephosphorization converter.The slag characteristics by the LWS and the HS methods and its application effects as the furnace burden are researched.The results show the moisture content in the HS slag is higher than that of the LWS slag.There is higher total iron content in the HS and the LWS slags and almost same melting point.The dicalcium silicate content in the LWS slag is higher than that in the HS slag.The tricalcium silicate in the LWS slag is lower than that in the HS slag.There are a lot of calcium ferrite in the LWS and the HS slags , which is beneficial to dephosphorization and slag melting.The LWS and the HS slags are added to dephosphorization converter each charge by 3or 6t.The results show that the saving lime is 0.7-1.0tfor each charge.The petrographic constitute of final slag for the dephosphorization converter by adding the LWS and the HS slags is dicalcium silicate , RO phase and glass phase.There are a little calcium ferrite phase in the LWS slag , which is helpful to dephosphorization.So there are better dephosphorization effects for the LWS and HS slags.
基金financially supported by the National Natural Science Foundation of China (No.U1960202)。
文摘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.
基金Sponsored by National Natural Science Foundation of China(51574024,51274042)China Postdoctoral Science Foundation(2015M580987,2016T90034)
文摘Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases （CO, H2, and CH4 ）, tar, and char was conducted to investigate the effects of reduction temperature, iron ore-biomass mass ratio, and reduction time on the metallization rate. In addition, the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation. It was determined that the metallization rate of the hematite ore could reach 99.35 % at iron ore-biomass mass ratio of 1 ： 0.6, reduction temperature of 1100℃, and reduction time of 55 min. The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature. The particle size of direct reduced iron （DRI） has a great influence on the quality of the iron concentrate during magnetic separation. The separation degree of slag and iron was improved by the addition of 15 mass% sodium carbonate. DRI with iron grade of 89.11%, iron recovery rate of 83.47%, and phosphorus content of 0.28% can be obtained when ore fines with particle size of -10μm account for 78.15%.
基金financially supported by the National Natu ral Science Foundation of China (No. U1960205)。
文摘High-phosphorus iron ore resource is considered a refractory iron ore because of its high-phosphorus content and complex ore phase structure. Therefore, the development of innovative technology to realize the efficient utilization of high-phosphorus iron ore resources is of theoretical and practical significance. Thus, a method for phosphorus removal by gasification in the hydrogen-rich sintering process was proposed. In this study, the reduction mechanism of phosphorus in hydrogen-rich sintering, as well as the reduction kinetics of apatite based on the non-isothermal kinetic method, was investigated. Results showed that, by increasing the reduction time from 20 to 60 min, the dephosphorization rate increased from 10.93%to 29.51%. With apatite reduction, the metal iron accumulates, and part of the reduced phosphorus gas is absorbed by the metal iron to form stable iron-phosphorus compounds, resulting in a significant reduction of the dephosphorization rate. Apatite reduction is mainly concentrated in the sintering and burning zones, and the reduced phosphorus gas moves downward along with flue gas under suction pressure and is condensed and adsorbed partly by the sintering bed when passing through the drying zone and over the wet zone. As a result, the dephosphorization rate is considerably reduced. Based on the Ozawa formula of the iso-conversion rate, the activation energy of apatite reduction is 80.42 kJ/mol. The mechanism function of apatite reduction is determined by a differential method (i.e., the Freeman-Carroll method) and an integral method (i.e., the Coats-Redfern method). The differential form of the equation is f(α)=2(1-α)^(1/2), and the integral form of the equation is G(α)=1-(1-α)^(1/2).
基金financially supported by the Fundamental Research Funds for Central Universities of China (No. CDJZR 14130001)
文摘Mass transfer of phosphorus in high-phosphorus hot-metal refining was investigated using CaO-FetO-SiO2 slags at 1623 K. Based on a two-film theory kinetic model and experimental results, it was found that the overall mass transfer coefficient, which includes the effects of mass transfer in both the slag phase and metal phase, is in the range of 0.0047 to 0.0240 cm/s. With the addition of a small amount of fluxing agents A1203 or Na20 into the slag, the overall mass transfer coefficient has an obvious increase. Silicon content in the hot metal also influences the overall mass transfer coefficient. The overall mass transfer coefficient in the lower [Si] heat is much higher than that in the higher [Si] heat. It is concluded that both fluxing agents and lower [Si] hot metal facilitate mass transfer of phosphorus in liquid phases. Fur- thermore, the addition of Na20 could also prevent rephosphorization at the end of the experiment.
文摘The formation of solid solution combined with tricalcium phosphate and dicalcium silicate could promote a considerable removal of phosphorus from liquid slag to solid during hot metal dephosphorization,and thus the dephosphorization by using multi phase fluxes could significantly decrease the consumption of lime. However,the reaction mechanism of multi phase fluxes has not been understood clearly.In the present study,the phase diagram for the CaO-SiO_2-FeO-P_2O_5 system has been measured with certain oxygen partial pressure at hot metal pretreatment temperature.Comparing with the CaO-SiO_2-FeO system,shrinkage of liquid phase area at higher FeO contents was observed at 1 673 K with oxygen partial pressure of 9.2×10^(-11) atm.
基金Project(51064015) supported by the National Natural Science Foundation of ChinaProject(ZD2010001) supported by the Key Project of Yunnan Province Education of China
文摘In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-phosphorus iron and ilmenite. The effect, which is related to basicity, reduction temperature, carbon-oxygen ratio and time of ventilated oxygen to iron recovery, dephosphorization rate, content of iron, phosphorus, sulfur and titanium in pig iron, was investigated in the experiment. The results show that an ideal outcome can be gained in condition of 6：4 ration on Mengqiao concentrate and Huimin iron ore, temperature of 1 500℃, basicity of 1.3, 1.0 on molar ration of carbon to oxygen, time of 10 min on blowing-oxygen. The outcome is that there is no foamy slag in generation, a good separation of slag and iron, iron recovery with 91.41%, content of phosphorus with 0.27% and tilanium content less than 0.001%, The atmosphere of strong oxidizing in the upper of reduction container and high potential of oxygen in the composition of slag in this technique bring phosphorus, titanium and silicon into slag, which ensures less content of impurity in pig iron.
