The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO...The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.展开更多
The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2...The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2)O_(3) dissolution was the diffusionin molten slag.It was found that the dissolution curves of Al_(2)O_(3) particles were hardly agreed with the traditional boundary layer diffusion model with the increase of the CaO/Al_(2)O_(3) ratio of slag.A modified diffusion equation considering slag viscosity was developed to study the dissolution mechanism of Al_(2)O_(3) in slag.Diffusion coefficients of Al_(2)O_(3) in slag were calculated as 2.8×10to 4.1×10m~2/s at the temperature of 1773-1873 K.The dissolution rate of Al_(2)O_(3) increased with higher temperature,CaO/Al_(2)O_(3),and particle size.A new model was shown to be v_(Al_(2)O_(3))=0.16×r_(0)^(1.58)×x^(3.52)×(T-T_(mp))^(1.11)to predict the dissolution rate and the total dissolution time of Al_(2)O_(3) inclusions with various sizes,where vAl_(2)O_(3) is the dissolution rate of Al_(2)O_(3) in volume,μm^(3)/s;x is the value of CaO/Al_(2)O_(3) mass ratio;R_(0) is the initial radius of Al_(2)O_(3),μm;T is the temperature,K;T_(mp) is the melting point of slag,K.展开更多
The experiments on the foaminess of the CaO-MgO-Al2O3 -SiO2 -CaF2 refining slag system have been carried out. The obtained results are as followst (1) relative foaming height linearly increases with the increasing of ...The experiments on the foaminess of the CaO-MgO-Al2O3 -SiO2 -CaF2 refining slag system have been carried out. The obtained results are as followst (1) relative foaming height linearly increases with the increasing of the flowrate of blowing gas; (2) the proper content of MgO is about 11% when slag basicity B<2.5 and it should lower when slag basicity will be higher; (3) the better content of Al2O3, (MgO)+(Al2O3 ) is 15% and 20 % ～ 26 % respectively at the range of lower basicities; (4) the effect of slag basicity on the foaminess is complex and its optimizing vaiue is 1.9 at the specific contents of MgO, Al2O3 and CaF2.展开更多
The rate of reducing Fet O in CaO-SiO2-Al2O3-Fet O slags with carbon saturated in molten iron has been determined in a graphite crucible in the temperature range of 1673-1773K. The effects of temperature, slag basicit...The rate of reducing Fet O in CaO-SiO2-Al2O3-Fet O slags with carbon saturated in molten iron has been determined in a graphite crucible in the temperature range of 1673-1773K. The effects of temperature, slag basicity and FetO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with increasing temperature or FEtO concentration in slags, and the reduction rate has a parabolic relation with the simple basicity or optical basicity of slag, the maximum reduction rate being observed at around CaO/SiO2=1.5 of molten slags. The reduction reaction order is 1. 73 or 1.80, and the reduction activation energy is 299.9 or 295.9 kJ/mol in regard to Fet O weight content or Fet O activity calculated by using regular solution model, respectively. The reduction rate of CaO-SiO2-Al2 O3-Fet O slags with carbon saturated in molten iron is in the range of 0.32-3.48 mol-O/cm2·s.展开更多
The reduction rate of Fe_tO in CaO-SiO_2-Al_2O_3-Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K.The effects of temperature,slag basicity and Fe_tO content on the reduction...The reduction rate of Fe_tO in CaO-SiO_2-Al_2O_3-Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K.The effects of temperature,slag basicity and Fe_tO content on the reduction rate have also been discussed.Test results show that the reduction rate increases with the increase of temperature or Fe_tO concentration in slags,and the reduction rate has a parabolic relation with slag simple basicity or optical basicity.The maximum reduction rate is observed around CaO/SiO_2 = l.5 of molten slags.The reaction order is 1.26 or 1.31,and the reduction activation energy is 126.8 or 129.7 kJ/mol respectively in regard to Fe_tO content or Fe_tO activity calculated by using regular solution model.The reduction rate of Fe_tO in CaO-SiO_2-Al_2O_3-Fe_tO slags with graphite powder is in the range of 0.15×10^(-4)- 0.86×10^(-4) mol-O/cm^2 · s.展开更多
The phosphorus-concentrating phase in the converter slags was designed and simulated by synthetic converter slag.The distribution of phosphorus in factory converter slags was also analyzed by scanning electron microsc...The phosphorus-concentrating phase in the converter slags was designed and simulated by synthetic converter slag.The distribution of phosphorus in factory converter slags was also analyzed by scanning electron microscope（SEM） and X-ray diffraction（XRD）.Then factory converter slags were modified by addition of SiO2 and heated to 1540℃and then cooled to room temperature.The results showed that the phosphorus in the factory converter slags was mostly distributed in two phases:dicalcium silicate （C2S） and tricalcium silicate（C3S） by formation of solid solution,and with a little in matrix.Whereas,in the synthetic slags with the basicity close to 3,phosphorus was almost concentrated in phase of C2S（Pconcentrating phase） in which the contents of P2O5 reach to 7.74%.This lays a good foundation for grinding and separation of P- concentrating phase.展开更多
The mass production of steel is inevitably accompanied by large quantities of slags.The treatment of ironmaking and steelmaking slags is a great challenge in the sustainable development of the steel industry.Japan and...The mass production of steel is inevitably accompanied by large quantities of slags.The treatment of ironmaking and steelmaking slags is a great challenge in the sustainable development of the steel industry.Japan and China are two major steel producing countries that have placed a large emphasis on developing new technologies to decrease slag emission or promote slag valorization.Slags are almost completely reused or recycled in Japan.However,due to stagnant infrastructural investments,future applications of slags in conventional sectors are expected to be difficult.Exploring new functions or applications of slags has become a research priority in Japan.For example,the utilization of steelmaking slags in offshore seabeds to create marine forests is under development.China is the top steel producer in the world.The utilization ratios of ironmaking and steelmaking slags have risen steadily in recent years,driven largely by technological advances.For example,hot stage processing of slags for materials as well as heat recovery techniques has been widely applied in steel plants with good results.However,increasing the utilization ratio of basic oxygen furnace slags remains a major challenge.Technological innovations in slag recycling are crucial for the steel industries in Japan and China.Here,the current status and developing trends of utilization technologies of slags in both countries are reviewed.展开更多
An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractorie...An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.展开更多
The effect of Al_(2)O_(3) content on the viscosity and structure of CaO-SiO_(2)-Cr_(2)O_(3)Al_(2)O_(3) slags was investigated to facilitate recycling of Cr in steelmaking slags.The slags exhibit good Newtonian behavio...The effect of Al_(2)O_(3) content on the viscosity and structure of CaO-SiO_(2)-Cr_(2)O_(3)Al_(2)O_(3) slags was investigated to facilitate recycling of Cr in steelmaking slags.The slags exhibit good Newtonian behavior at high temperature.The viscosity of acidic slag first increases from 0.825 to 1.141 Pa·s as the Al_(2)O_(3) content increases from 0 to 10wt%and then decreases to 1.071 Pa·s as the Al_(2)O_(3) content increases further to 15wt%.The viscosity of basic slag first increases from 0.084 to 0.158 Pa·s as the Al_(2)O_(3) content increases from 0 to 15wt%and then decreases to 0.135 Pa·s as the Al_(2)O_(3) content increases further to 20wt%.Furthermore,Cr_(2)O_(3)containing slag requires less Al_(2)O_(3) to reach the maximum viscosity than Cr_(2)O_(3)free slag;the Al_(2)O_(3) contents at which the behavior changes are 10wt%and 15wt%for acidic and basic slags,respectively.The ac-tivation energy of the slags is consistent with the viscosity results.Raman spectra demonstrate that[AlO_(4)]tetrahedra appear initially and were replaced by[AlO_(6)]octahedra with further addition of Al_(2)O_(3).The dissolved organic phosphorus content of the slag first increases and then de-creases with increasing Al_(2)O_(3) content,which is consistent with the viscosity and Raman results.展开更多
The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-A12O3-Fe,O- MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron contai...The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-A12O3-Fe,O- MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1 873 K. The Mn distribution ratio Lmn increases with increasing FetO content and decreasing the basicity (%CaO + %MgO)/ (%SiO2 + %Al2O3 + %P2O5) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of LM, and Lmn decrease by the addition of A12O3 into slag. The expression of the dependence of Lmn. and Lp on the basicity and FetO content in slag was obtained.展开更多
In the present work,the solubility of water vapour in tundish slag has been studied in the temperature range from 1 400 C to 1 600 C by a thermogravimetric technique.The water vapour capacity of the slags was calculat...In the present work,the solubility of water vapour in tundish slag has been studied in the temperature range from 1 400 C to 1 600 C by a thermogravimetric technique.The water vapour capacity of the slags was calculated and compared with the data from earlier studies.The results confirm that the solubility of water vapour in slags increases with increasing water vapour pressure.The relation between the two parameters obeys Sievert's law.For slags with optical basicities from 0.5 to 0.8,a regression equation was obtained to express the relation between the water vapour capacity and optical basicity of slags.A tundish slag system with the desired properties can be designed according to the correlations between the optical basicity and various capacities of slags.展开更多
The activity of CaO and La<sub>2</sub>O<sub>3</sub> in the liquid ternary slay CaO-SiO<sub>2</sub>-La<sub>2</sub>O<sub>3</sub> has been de-termined by equili...The activity of CaO and La<sub>2</sub>O<sub>3</sub> in the liquid ternary slay CaO-SiO<sub>2</sub>-La<sub>2</sub>O<sub>3</sub> has been de-termined by equilibrating Sn with the slag phase in a graphite crucible under l arm of CO at1600C.The experimental results ,showed that the activity of CaO and La<sub>2</sub>O<sub>3</sub> changes slowlywhile the ratio of mole fraction.x<sub>CaO</sub>/x<sub>SiO<sub>2</sub></sub>,is less than unit.hut varies sharply while the ra-rio increases from 1 to 1.2.In addition,by equilibrating Sn with the binary slagB<sub>2</sub>O<sub>3</sub>-La<sub>2</sub>O<sub>3</sub> saturated witlt solid La<sub>2</sub>O<sub>3</sub> at three different temperatures,the relation betweenIgγ<sub>La</sub><sup>0</sup> and I/T is determined as follows:Igγ<sub>La</sub><sup>0</sup>=-20400/T+11.37（1500-1600C）A random network model of molten silicate structure was applied to CaO-SiO<sub>2</sub>-La2O<sub>3</sub>.It was found that the experimentally determined activity-composition curve of CaO arequalitatively reproduced by the curves calculated with the model,but the curves of La<sub>2</sub>O<sub>3</sub> areconsiderahly different from the calculated ones.It implies that the model used is over-simpli-fied and that the difference in interaction energy between the metal cations of different valenceand silicate anions should be considered.展开更多
The activity of MnO in blast furnace-typeslags CaO-SiO<sub>2</sub>,CaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> andCaO-SiO<sub>2</sub>-Al<sub>2</...The activity of MnO in blast furnace-typeslags CaO-SiO<sub>2</sub>,CaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> andCaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>-MgO at 1500℃ has been measuredin a graphite crucible with Ag and Sn as solventmetals.The agreement between the values ofγMnO obtained from the experimental resultsusing Ag and Sn separately as the solvent metalis excellent.The major errors in the previousstudies have proved to be the failure to takeinto account the exchange reactions involvingSi and Mn and insufficient time for theestablishment of equilibrium between slag andsolvent metal.A new method is suggested for determiningthe activities of elements in metallic solutions.The method involves the separate equilibrationof two metallic alloys,one of which containsthe component of interest at a known activity,with a single slag.展开更多
Under inert atmospheres and 1473 K,the evaporation rate of SnS from SnO-FeO-SiO<sub>2</sub> and SnO-FeO-CaO-SiO<sub>2</sub> slags mixed with FeS was investigated by measuringthe weight Ioss and...Under inert atmospheres and 1473 K,the evaporation rate of SnS from SnO-FeO-SiO<sub>2</sub> and SnO-FeO-CaO-SiO<sub>2</sub> slags mixed with FeS was investigated by measuringthe weight Ioss and composition of samples.The experimental results show that dur-ing sulfide fuming process the evaporation of SnOfrom slags is negligible in comparisonwith that of SnS.Addition of CaOto slags can enhance the evaporation rate of SnS.Thedifferential rate equation of evaporation may be expressed as:-d（%Sn）/dt=k（%Sn）（%S）where,the apparent rate constant k was found to be 4.20×10<sup>-3</sup> for SnO-FeO-CaO-SiO<sub>2</sub> system and 2.88×10<sup>-3</sup> for SnO-FeO-SiO<sub>2</sub> system,respectively.展开更多
According to the coexistence theory of slag structure melts, the oxidizing capability of the refining slag CaO-MgO-FeO- A12O3SiO2 is studied and the relationship between the mass action concentration of FeO (NFeO) and...According to the coexistence theory of slag structure melts, the oxidizing capability of the refining slag CaO-MgO-FeO- A12O3SiO2 is studied and the relationship between the mass action concentration of FeO (NFeO) and the activity of FetO (αFetO) for this slag is found to be as NFeo=0.656 1 αFetO. Furthermore, the calculating model of oxidizing capability of the refining slag BaO-CaO-MgO- FeOA12O3-SiO2 is established. A satisfactory result is obtained when using the above oxidizing capability relationship to calculate the desulphurizing capability of such refining BaO-slags.展开更多
We investigated the effect of Al2O3 content on the viscosity of CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3(mass ratio of CaO/SiO2 is 1.0,and Al2O3 content is 17wt%-29wt%)slags.The results show that the viscosity of the slag inc...We investigated the effect of Al2O3 content on the viscosity of CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3(mass ratio of CaO/SiO2 is 1.0,and Al2O3 content is 17wt%-29wt%)slags.The results show that the viscosity of the slag increases gradually with increases in the Al2O3 content in the range of 17wt%to 29wt%due to the role of Al2O3 as a network former in the polymerization of the aluminosilicate structure of the slag.With increases in the Al2O3 content from 17wt%to 29wt%,the apparent activation energy of the slags also increases from 180.85 to 210.23 kJ/mol,which is consistent with the variation in the critical temperature.The Fourier-transform infrared spectra indicate that the degree of polymerization of this slag is increased by the addition of Al2O3.The application of Iida’s model for predicting the slag viscosity in the presence of Cr2O3 indicates that the calculated viscosity values fit well with the measured values when both the temperature and Al2O3 content are at relatively low levels,i.e.,the temperature range of 1673 to 1803 K and the Al2O3 content range of 17wt%-29wt%in CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3 slag.展开更多
Thermodynamics of Ti in liquid steels and slags was studied in order to establish a data base for the prediction of TiOx and TiN formation in liquid steels.The interaction parameters between Ti and i（i = Cr,Ti,Al, Si...Thermodynamics of Ti in liquid steels and slags was studied in order to establish a data base for the prediction of TiOx and TiN formation in liquid steels.The interaction parameters between Ti and i（i = Cr,Ti,Al, Si,Ni,Mo,Nb,N,O） in liquid iron and the equilibrium constants for the formation of TiN and TiOx in liquid iron were determined as a function of temperature.In view of high Ti yield during ladle treatment,thermodynamics of titanium oxides in ladle slags was studied as well.Activity coefficient and redox equilibrium of TiOx in MgO saturated CaO-Al2O3 slag are also discussed by measuring the distribution ratio of Ti between slag and iron melts and the Ti3+/Ti4+ ratio in slag at 1 873 K.展开更多
The phase equilibrium information of slag plays an important role in pyrometallurgical processes to obtain optimum fluxing conditions and operating temperatures.The smelting reduction of titanomagnetite and ilmenite o...The phase equilibrium information of slag plays an important role in pyrometallurgical processes to obtain optimum fluxing conditions and operating temperatures.The smelting reduction of titanomagnetite and ilmenite ores in an iron blast furnace(BF)can form Ti(C,N)particles,causing the increased viscosities of slag and hot metal.HIsmelt has been developed in recent years for ironmaking and does not need coke and sinter.The formation of Ti(C,N)in the HIsmelt process is avoided because the oxygen partial pressure in the process is higher than that in the BF.The smelting of TiO_(2)-containing ores in the HIsmelt process results in Al_(2)O_(3)-MgO-SiO_(2)-CaO-TiO_(2)slag.Phase equilibrium in this slag system has been investigated using equilibration,quenching,and electron probe microanalysis techniques.The experimental results were presented in two pseudo-binary sections,which represent the process of HIsmelt for the treatment of 100%titanomagnetite ore and mixed titanomagnetite+ilmenite ore(mass ratio of 2:1),respectively.The primary phases observed in the composition range investigated include pseudo-brookite M_(3)O_(5)(MgO·2TiO_(2)-Al_(2)O_(3)·TiO_(2)),spinel(MgO·Al_(2)O_(3)),perovskite CaTiO_(3),and rutile TiO_(2).The results show that the liquidus temperatures decrease in the TiO_(2)and M_(3)O_(5) primary phase fields and increase in the spinel and CaTiO_(3)primary phase fields with the increase in CaO concentration.The calculation of solid-phase fractions from the experimental data has been demonstrated.The effect of basicity on the liquidus temperatures of the slag has been discussed.The smelting of titanomagnetite plus ilmenite ores has significant advantages to obtain low-sulfur hot metal and high-TiO_(2)slag.Experimentally determined liquidus temperatures were compared with the FactSage predictions to evaluate the existing thermodynamic databases.展开更多
The application of ferrous slags as aggregate, road bed materials, soil fertility conditioner and as clinker materials depend on their chemical and mineralogical characteristics. In order to assess the possibilities o...The application of ferrous slags as aggregate, road bed materials, soil fertility conditioner and as clinker materials depend on their chemical and mineralogical characteristics. In order to assess the possibilities of using ferrous slags generated in Ghana, selected slag samples from some foundries have been characterized. A total of six bulk samples were collected from three different foundry shops to determine their chemical and mineralogical composition. The slag samples showed varied chemical and mineralogical characteristics. Differences are as a result of the differences in furnace charge, operation temperatures, grades of refractory furnace lining and melting additives. Calcium oxide (CaO) contents observed in all investigated samples were in combined form (i.e. not free CaO). The low amounts of calcium oxide in the slag samples limit their applications in the area of cement/aggregate production. Even though slags were found to be alkaline, for these slags to effectively neutralize the acidity of soil and improve its fertility, components such as CaO, SiO2, MgO and FeO in the slag must be improved. However, these slags could be used as road bed materials.展开更多
基金supported by the National Natural Science Foundation of China(21878082).
文摘The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.
基金financially supported by the National Nature Science Foundation of China(Nos.U1860206,51725402)the Science and Technology Program of Hebei,China(Nos.20311006D,20591001D)。
文摘The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2)O_(3) dissolution was the diffusionin molten slag.It was found that the dissolution curves of Al_(2)O_(3) particles were hardly agreed with the traditional boundary layer diffusion model with the increase of the CaO/Al_(2)O_(3) ratio of slag.A modified diffusion equation considering slag viscosity was developed to study the dissolution mechanism of Al_(2)O_(3) in slag.Diffusion coefficients of Al_(2)O_(3) in slag were calculated as 2.8×10to 4.1×10m~2/s at the temperature of 1773-1873 K.The dissolution rate of Al_(2)O_(3) increased with higher temperature,CaO/Al_(2)O_(3),and particle size.A new model was shown to be v_(Al_(2)O_(3))=0.16×r_(0)^(1.58)×x^(3.52)×(T-T_(mp))^(1.11)to predict the dissolution rate and the total dissolution time of Al_(2)O_(3) inclusions with various sizes,where vAl_(2)O_(3) is the dissolution rate of Al_(2)O_(3) in volume,μm^(3)/s;x is the value of CaO/Al_(2)O_(3) mass ratio;R_(0) is the initial radius of Al_(2)O_(3),μm;T is the temperature,K;T_(mp) is the melting point of slag,K.
文摘The experiments on the foaminess of the CaO-MgO-Al2O3 -SiO2 -CaF2 refining slag system have been carried out. The obtained results are as followst (1) relative foaming height linearly increases with the increasing of the flowrate of blowing gas; (2) the proper content of MgO is about 11% when slag basicity B<2.5 and it should lower when slag basicity will be higher; (3) the better content of Al2O3, (MgO)+(Al2O3 ) is 15% and 20 % ～ 26 % respectively at the range of lower basicities; (4) the effect of slag basicity on the foaminess is complex and its optimizing vaiue is 1.9 at the specific contents of MgO, Al2O3 and CaF2.
文摘The rate of reducing Fet O in CaO-SiO2-Al2O3-Fet O slags with carbon saturated in molten iron has been determined in a graphite crucible in the temperature range of 1673-1773K. The effects of temperature, slag basicity and FetO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with increasing temperature or FEtO concentration in slags, and the reduction rate has a parabolic relation with the simple basicity or optical basicity of slag, the maximum reduction rate being observed at around CaO/SiO2=1.5 of molten slags. The reduction reaction order is 1. 73 or 1.80, and the reduction activation energy is 299.9 or 295.9 kJ/mol in regard to Fet O weight content or Fet O activity calculated by using regular solution model, respectively. The reduction rate of CaO-SiO2-Al2 O3-Fet O slags with carbon saturated in molten iron is in the range of 0.32-3.48 mol-O/cm2·s.
文摘The reduction rate of Fe_tO in CaO-SiO_2-Al_2O_3-Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K.The effects of temperature,slag basicity and Fe_tO content on the reduction rate have also been discussed.Test results show that the reduction rate increases with the increase of temperature or Fe_tO concentration in slags,and the reduction rate has a parabolic relation with slag simple basicity or optical basicity.The maximum reduction rate is observed around CaO/SiO_2 = l.5 of molten slags.The reaction order is 1.26 or 1.31,and the reduction activation energy is 126.8 or 129.7 kJ/mol respectively in regard to Fe_tO content or Fe_tO activity calculated by using regular solution model.The reduction rate of Fe_tO in CaO-SiO_2-Al_2O_3-Fe_tO slags with graphite powder is in the range of 0.15×10^(-4)- 0.86×10^(-4) mol-O/cm^2 · s.
文摘The phosphorus-concentrating phase in the converter slags was designed and simulated by synthetic converter slag.The distribution of phosphorus in factory converter slags was also analyzed by scanning electron microscope（SEM） and X-ray diffraction（XRD）.Then factory converter slags were modified by addition of SiO2 and heated to 1540℃and then cooled to room temperature.The results showed that the phosphorus in the factory converter slags was mostly distributed in two phases:dicalcium silicate （C2S） and tricalcium silicate（C3S） by formation of solid solution,and with a little in matrix.Whereas,in the synthetic slags with the basicity close to 3,phosphorus was almost concentrated in phase of C2S（Pconcentrating phase） in which the contents of P2O5 reach to 7.74%.This lays a good foundation for grinding and separation of P- concentrating phase.
文摘The mass production of steel is inevitably accompanied by large quantities of slags.The treatment of ironmaking and steelmaking slags is a great challenge in the sustainable development of the steel industry.Japan and China are two major steel producing countries that have placed a large emphasis on developing new technologies to decrease slag emission or promote slag valorization.Slags are almost completely reused or recycled in Japan.However,due to stagnant infrastructural investments,future applications of slags in conventional sectors are expected to be difficult.Exploring new functions or applications of slags has become a research priority in Japan.For example,the utilization of steelmaking slags in offshore seabeds to create marine forests is under development.China is the top steel producer in the world.The utilization ratios of ironmaking and steelmaking slags have risen steadily in recent years,driven largely by technological advances.For example,hot stage processing of slags for materials as well as heat recovery techniques has been widely applied in steel plants with good results.However,increasing the utilization ratio of basic oxygen furnace slags remains a major challenge.Technological innovations in slag recycling are crucial for the steel industries in Japan and China.Here,the current status and developing trends of utilization technologies of slags in both countries are reviewed.
基金financially supported by the National Key R&D Program of China (No. 2018YFC1902004)the National Natural Science Foundation of China (No. U1608254)+1 种基金the Project for Guangdong Collaborative Innovation and Platform Environment Building (No. 2017B090904035)the Special Project for Key Laboratory of Guangdong Science and Technology Department, China (No. 2017B030314046)
文摘An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.
基金This work was financially supported by the National Natural Science Foundation of China(No.U1960201)the National Key R&D Program of China(No.2019YFC 1905701).
文摘The effect of Al_(2)O_(3) content on the viscosity and structure of CaO-SiO_(2)-Cr_(2)O_(3)Al_(2)O_(3) slags was investigated to facilitate recycling of Cr in steelmaking slags.The slags exhibit good Newtonian behavior at high temperature.The viscosity of acidic slag first increases from 0.825 to 1.141 Pa·s as the Al_(2)O_(3) content increases from 0 to 10wt%and then decreases to 1.071 Pa·s as the Al_(2)O_(3) content increases further to 15wt%.The viscosity of basic slag first increases from 0.084 to 0.158 Pa·s as the Al_(2)O_(3) content increases from 0 to 15wt%and then decreases to 0.135 Pa·s as the Al_(2)O_(3) content increases further to 20wt%.Furthermore,Cr_(2)O_(3)containing slag requires less Al_(2)O_(3) to reach the maximum viscosity than Cr_(2)O_(3)free slag;the Al_(2)O_(3) contents at which the behavior changes are 10wt%and 15wt%for acidic and basic slags,respectively.The ac-tivation energy of the slags is consistent with the viscosity results.Raman spectra demonstrate that[AlO_(4)]tetrahedra appear initially and were replaced by[AlO_(6)]octahedra with further addition of Al_(2)O_(3).The dissolved organic phosphorus content of the slag first increases and then de-creases with increasing Al_(2)O_(3) content,which is consistent with the viscosity and Raman results.
文摘The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-A12O3-Fe,O- MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1 873 K. The Mn distribution ratio Lmn increases with increasing FetO content and decreasing the basicity (%CaO + %MgO)/ (%SiO2 + %Al2O3 + %P2O5) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of LM, and Lmn decrease by the addition of A12O3 into slag. The expression of the dependence of Lmn. and Lp on the basicity and FetO content in slag was obtained.
文摘In the present work,the solubility of water vapour in tundish slag has been studied in the temperature range from 1 400 C to 1 600 C by a thermogravimetric technique.The water vapour capacity of the slags was calculated and compared with the data from earlier studies.The results confirm that the solubility of water vapour in slags increases with increasing water vapour pressure.The relation between the two parameters obeys Sievert's law.For slags with optical basicities from 0.5 to 0.8,a regression equation was obtained to express the relation between the water vapour capacity and optical basicity of slags.A tundish slag system with the desired properties can be designed according to the correlations between the optical basicity and various capacities of slags.
文摘The activity of CaO and La<sub>2</sub>O<sub>3</sub> in the liquid ternary slay CaO-SiO<sub>2</sub>-La<sub>2</sub>O<sub>3</sub> has been de-termined by equilibrating Sn with the slag phase in a graphite crucible under l arm of CO at1600C.The experimental results ,showed that the activity of CaO and La<sub>2</sub>O<sub>3</sub> changes slowlywhile the ratio of mole fraction.x<sub>CaO</sub>/x<sub>SiO<sub>2</sub></sub>,is less than unit.hut varies sharply while the ra-rio increases from 1 to 1.2.In addition,by equilibrating Sn with the binary slagB<sub>2</sub>O<sub>3</sub>-La<sub>2</sub>O<sub>3</sub> saturated witlt solid La<sub>2</sub>O<sub>3</sub> at three different temperatures,the relation betweenIgγ<sub>La</sub><sup>0</sup> and I/T is determined as follows:Igγ<sub>La</sub><sup>0</sup>=-20400/T+11.37（1500-1600C）A random network model of molten silicate structure was applied to CaO-SiO<sub>2</sub>-La2O<sub>3</sub>.It was found that the experimentally determined activity-composition curve of CaO arequalitatively reproduced by the curves calculated with the model,but the curves of La<sub>2</sub>O<sub>3</sub> areconsiderahly different from the calculated ones.It implies that the model used is over-simpli-fied and that the difference in interaction energy between the metal cations of different valenceand silicate anions should be considered.
文摘The activity of MnO in blast furnace-typeslags CaO-SiO<sub>2</sub>,CaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> andCaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>-MgO at 1500℃ has been measuredin a graphite crucible with Ag and Sn as solventmetals.The agreement between the values ofγMnO obtained from the experimental resultsusing Ag and Sn separately as the solvent metalis excellent.The major errors in the previousstudies have proved to be the failure to takeinto account the exchange reactions involvingSi and Mn and insufficient time for theestablishment of equilibrium between slag andsolvent metal.A new method is suggested for determiningthe activities of elements in metallic solutions.The method involves the separate equilibrationof two metallic alloys,one of which containsthe component of interest at a known activity,with a single slag.
文摘Under inert atmospheres and 1473 K,the evaporation rate of SnS from SnO-FeO-SiO<sub>2</sub> and SnO-FeO-CaO-SiO<sub>2</sub> slags mixed with FeS was investigated by measuringthe weight Ioss and composition of samples.The experimental results show that dur-ing sulfide fuming process the evaporation of SnOfrom slags is negligible in comparisonwith that of SnS.Addition of CaOto slags can enhance the evaporation rate of SnS.Thedifferential rate equation of evaporation may be expressed as:-d（%Sn）/dt=k（%Sn）（%S）where,the apparent rate constant k was found to be 4.20×10<sup>-3</sup> for SnO-FeO-CaO-SiO<sub>2</sub> system and 2.88×10<sup>-3</sup> for SnO-FeO-SiO<sub>2</sub> system,respectively.
基金The authors thank for the instrUction of Prof. Jian Zhang of the University of Science and Technology Beliing and the financia
文摘According to the coexistence theory of slag structure melts, the oxidizing capability of the refining slag CaO-MgO-FeO- A12O3SiO2 is studied and the relationship between the mass action concentration of FeO (NFeO) and the activity of FetO (αFetO) for this slag is found to be as NFeo=0.656 1 αFetO. Furthermore, the calculating model of oxidizing capability of the refining slag BaO-CaO-MgO- FeOA12O3-SiO2 is established. A satisfactory result is obtained when using the above oxidizing capability relationship to calculate the desulphurizing capability of such refining BaO-slags.
基金This work was financially supported by the Fundamental Research Funds for the Central Universities of China(Nos.FRF-TP-20-048A2 and FRF-AT-20-02).
文摘We investigated the effect of Al2O3 content on the viscosity of CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3(mass ratio of CaO/SiO2 is 1.0,and Al2O3 content is 17wt%-29wt%)slags.The results show that the viscosity of the slag increases gradually with increases in the Al2O3 content in the range of 17wt%to 29wt%due to the role of Al2O3 as a network former in the polymerization of the aluminosilicate structure of the slag.With increases in the Al2O3 content from 17wt%to 29wt%,the apparent activation energy of the slags also increases from 180.85 to 210.23 kJ/mol,which is consistent with the variation in the critical temperature.The Fourier-transform infrared spectra indicate that the degree of polymerization of this slag is increased by the addition of Al2O3.The application of Iida’s model for predicting the slag viscosity in the presence of Cr2O3 indicates that the calculated viscosity values fit well with the measured values when both the temperature and Al2O3 content are at relatively low levels,i.e.,the temperature range of 1673 to 1803 K and the Al2O3 content range of 17wt%-29wt%in CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3 slag.
文摘Thermodynamics of Ti in liquid steels and slags was studied in order to establish a data base for the prediction of TiOx and TiN formation in liquid steels.The interaction parameters between Ti and i（i = Cr,Ti,Al, Si,Ni,Mo,Nb,N,O） in liquid iron and the equilibrium constants for the formation of TiN and TiOx in liquid iron were determined as a function of temperature.In view of high Ti yield during ladle treatment,thermodynamics of titanium oxides in ladle slags was studied as well.Activity coefficient and redox equilibrium of TiOx in MgO saturated CaO-Al2O3 slag are also discussed by measuring the distribution ratio of Ti between slag and iron melts and the Ti3+/Ti4+ ratio in slag at 1 873 K.
文摘The phase equilibrium information of slag plays an important role in pyrometallurgical processes to obtain optimum fluxing conditions and operating temperatures.The smelting reduction of titanomagnetite and ilmenite ores in an iron blast furnace(BF)can form Ti(C,N)particles,causing the increased viscosities of slag and hot metal.HIsmelt has been developed in recent years for ironmaking and does not need coke and sinter.The formation of Ti(C,N)in the HIsmelt process is avoided because the oxygen partial pressure in the process is higher than that in the BF.The smelting of TiO_(2)-containing ores in the HIsmelt process results in Al_(2)O_(3)-MgO-SiO_(2)-CaO-TiO_(2)slag.Phase equilibrium in this slag system has been investigated using equilibration,quenching,and electron probe microanalysis techniques.The experimental results were presented in two pseudo-binary sections,which represent the process of HIsmelt for the treatment of 100%titanomagnetite ore and mixed titanomagnetite+ilmenite ore(mass ratio of 2:1),respectively.The primary phases observed in the composition range investigated include pseudo-brookite M_(3)O_(5)(MgO·2TiO_(2)-Al_(2)O_(3)·TiO_(2)),spinel(MgO·Al_(2)O_(3)),perovskite CaTiO_(3),and rutile TiO_(2).The results show that the liquidus temperatures decrease in the TiO_(2)and M_(3)O_(5) primary phase fields and increase in the spinel and CaTiO_(3)primary phase fields with the increase in CaO concentration.The calculation of solid-phase fractions from the experimental data has been demonstrated.The effect of basicity on the liquidus temperatures of the slag has been discussed.The smelting of titanomagnetite plus ilmenite ores has significant advantages to obtain low-sulfur hot metal and high-TiO_(2)slag.Experimentally determined liquidus temperatures were compared with the FactSage predictions to evaluate the existing thermodynamic databases.
文摘The application of ferrous slags as aggregate, road bed materials, soil fertility conditioner and as clinker materials depend on their chemical and mineralogical characteristics. In order to assess the possibilities of using ferrous slags generated in Ghana, selected slag samples from some foundries have been characterized. A total of six bulk samples were collected from three different foundry shops to determine their chemical and mineralogical composition. The slag samples showed varied chemical and mineralogical characteristics. Differences are as a result of the differences in furnace charge, operation temperatures, grades of refractory furnace lining and melting additives. Calcium oxide (CaO) contents observed in all investigated samples were in combined form (i.e. not free CaO). The low amounts of calcium oxide in the slag samples limit their applications in the area of cement/aggregate production. Even though slags were found to be alkaline, for these slags to effectively neutralize the acidity of soil and improve its fertility, components such as CaO, SiO2, MgO and FeO in the slag must be improved. However, these slags could be used as road bed materials.
