Simulation on Slag Splashing for LD Converter

SeveraL parameters affecting slag splashing in LD converter have been discussed. Using parffin and starch model, a simulated test about 30 t converter has been made in laboratory and the modified Frode numberwas chosen as the main similar basis of the system. It was results that the optimized slag splashing parameters wasobtained through data treatment The nitrogen gas flow rate is about 8 500 m3/h, the splashing time is of 3 min,and the lance height is of 0.8 m. It is necessary to add MgO or carbon into the slag to adjusting slag composition.Also, it is difficult for the splashed slag condensing on the line when the slag temperature is much higher

CFD Analysis of Influence of Slag Viscosity on the Splashing Process in an Oxygen Steelmaking Converter

Physical properties of molten slag such as viscosity, density and surface tension have a significant influence on the slag splashing process in an oxygen steelmaking converter. Particularly, viscosity determines the shear forces that rule droplets formation. Besides, stirring of the molten slag bath strongly depends on this property. In this work, the influence of viscosity on the efficiency of slag splashing is explored by means of transient Computational Fluid Dynamics simulations. Several values of viscosity are employed in the computer experiments. In order to quantify the splashing efficiency as function of slag viscosity, an average slag fraction on the converter walls is defined and calculated. CFD results are compared with those of an empirical expression, and at least qualitative agreement is found.

Numerical Analysis of Slag Splashing in a Steelmaking Converter

Some variables that influence the slag splashing phenomenon in an oxygen steelmaking converter are numerically analyzed in this work. The effect of lance height, jet velocity, jet exit angle and slag viscosity on the washing and ejection mechanisms of slag splashing is studied employing transient two-dimensional computational fluid dynamics simulations. A parameter here called average slag volume fraction is proposed for the quantitative evaluation of the slag splashing efficiency. Besides, a qualitative comparison is made between the computational fluid dynamics results and physical model results from literature.

Recovery of cobalt from converter slag of Chambishi Copper Smelter using reduction smelting process

The reduction smelting process for cobalt recovery from converter slag of the Chambishi Copper Smelter in Zambia was studied. The effects of reducing agent dosage, smelting temperature and time and the addition of slag modifiers （CaO and TiO2） were investigated. In addition, the depleted slag and cobalt-bearing alloy were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Under the determined conditions, 94.02% Co, 95.76% Cu and less than 18% Fe in the converter slag were recovered. It was found that the main phases of depleted slag were fayalite and hercynite; and the cobalt-bearing alloy mainly contained metallic copper, Fe-Co-Cu alloys and a small amount of sulfide.

φ-pH diagram of V-Ti-H_2O system during pressure acid leaching of converter slag containing vanadium and titanium

To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.

Chemical and mineralogical characterizations of a copper converter slag

A copper converter slag was examined chemically and mineralogically to determine its existing phases, in particular those containing Co and Cu. The slag consists predominantly of fayalite and magnetite, together with some glass, chalcocite, and metallic copper. Copper is entrapped in the slag mostly as chalcocite and metallic copper, as well as trace copper oxide. There was no indication of any independent Co mineral in the slag, but Co was found to be enriched in fayalite and megnetite as solid solution, although Co was detected in all the phases of the slag by SEM-EDX (scanning electron microscopy equipped with model EDAX-9100 energy dispersive spectrometer) and WDS (model WDX-2A X-ray wave-length dispersive spectrometer).

Enhancement of the nickel converter slag-cleaning operation with the addition of spent potlining

The slag cleaning(or matte settling) process was experimentally investigated at 1573 K using a fayalitic nickel converter slag containing spinel and matte/alloy particles.The addition of various amounts of spent potlining(SPL) was studied in terms of its influence on matte settling and the overall metal recoveries.The slags produced were characterized by scanning electron microscopy,energy-dispersive spectroscopy,and wet chemical analysis using inductively coupled plasma optical emission spectrometry.The presence of solid spinel particles in the molten slag hindered coalescence and settling of matte/alloy droplets.Matte settling was effectively promoted with the addition of as little as 2 wt% SPL because of the reduction of spinel by the carbonaceous component of the SPL.The reduced viscosity of the molten slag in the presence of SPL also contributed to the accelerated matte settling.Greater metal recoveries were achieved with larger amounts of added SPL.Fast reduction of the molten slag at 1573 K promoted the formation of highly dispersed metal particles/clusters via accelerated nucleation in the molten slag,which increased the overall slag viscosity.This increase in viscosity,when combined with rapid gas evolution from accelerated reduction reactions,led to slag foaming.

Hydrophobic-surface of copper from converter slag in the flotation system

The converter slag from a smeltery in Daye contains 2.01% copper.The floatability of copper has a significant influence on the flotation of converter slag.Flotation tests,contact angle tests and FTIR were conducted to assess the influences of pH and different flotation concentrators on its hydrophobic process,mechanism and flotation.The results show that since chemisorptions are formed on the surface,hydrophobicity of copper is highly enhanced by xanthate,butylamine dithiophosphate and Z-200.The hydrophobic-surface of copper becomes worse with low recovery in strong acid and alkali situation.When pH value is 10,butylamine dithiophosphate and butyl xanthate are used as the mixed-collector,the grade of copper is 40.01%and that of tailings is 0.37%.

Investigation on the Copper Content of Matte Smelting Slag in Peirce-Smith Converter

The copper contents and its existing forms in the slags during the slag-making stage of Peirce-Smith converters in Guixi Smelter, Jiangxi Province, China have been investigated. The investigation was based on plant trials with the corresponding thermodynamic calculations and kinetic considerations. From the plant data, the total copper content in the slags was in the range of 2% to 8% (mass fraction). The mechanical entrainment of matte drops has been found to be the main cause of the copper loss. The suspension index, defined as the ratio of the mass fraction of copper in suspended matte drops in the slag to that in bulk of the matte phase, has been adopted to quantify the matte entrainment. The values of this parameter estimated in this work have been found mainly within a range of 2.5%-8.0%. The Fe3O4 content in the slag has been estimated to be the most important factor, among others, influencing the separation of slag with matte and, consequently, the copper loss from the slag.

Recovery of Copper and Cobalt from Converter Slag with a New Flotation Method Using H_(2）S

In this study,two different samples were obtained from Küre Copper factory.It was determined that the samples contain:the sample of K.C.F.(Küre Copper Factory),0.70%Cu and 0.5%Co.This sample was firstly grounded at-100 mesh dimension.Flotation was done according to previously obtained optimum flotation conditions.The flotation yield of Cu and Co in concentrate phase was found to be low by collective flotation.Even when the samples were grounded at-160 mesh,no change was observed in the flotation result.Especially,Co could not float under the flotation conditions of the non-sulfurized samples.There,a new flotation method was applied which was not applied until now.For this aim,the samples were firstly sulphurised under the steam of H2S+H2O.By this method,the amount of Cu and Co in the samples get rich.According to the obtained results,the optimum reactions for flotation and sulphurization were determined.In the first sulphurization conditions for the sample of K.C.F.,the yield of flotation for the Co and Co were found to be 98.27%and 68.07%,respectively.The results indicate that Cu can be floated at low yield in the original samples.On the other hand,Co cannot float under these conditions.

Thermodynamic Study on Process in Copper Converters(The slag-making stage)

The so-called Goto's model was modified by introducing a parameter of the oxygen efficiency from industrial trials, as well as the selected and newly re-assessed thermodynamic data. The application of the model to copper converters in Guixi Smelter has been carried out by the combination of thermodynamic calculations with the mass and heat balance using the plant data obtained in industrial trials for many heats. For the slag-making stage, good agreements have been reached betWeen the calculated and measured temperature, blowing time as well as the contents for main elements in the matte and the slag. Relativel}'' large deviations for contents of Zn and Pb in the slag may be caused by the complex chemical composition of the real molten slag, which ma}; result in a large difference of γzn. and γPb,adopted with their real values. It is noted that the model can simulate the slag-making stage of copper converting process in industrial Pierce-Smith converters well.

Brief of the technology using sliding gate for slag stopping during converter tapping in the steelmaking plant of Baoshan Iron & Steel Co.,Ltd.

The sliding gate used to stop slag during converter tapping is similar to the control of slide gate in ladle,with the sliding gate device installed outside the BOF tapping hole tip.Owing to the quick opening and closing(in 0.5 s) of the sliding gate,it can not only effectively stop the pre - slag and post - slag during converter tapping but also automatically judge and stop slag with the help of AMEPA slag detecting and PLC control technology.Currently it is regarded as the best process to stop slag during converter tapping.

The study of microstructure and phosphorus distribution in converter slag

An efficient slagging is a key process to improve the dephosphorization ability in converter operation. The microstructure analyses can provide the information of phosphorus distribution in various mineral phases to feature completely the dephosphorization process.Two kinds of converter slags were investigated in this study, including conventional slag with high basicity and dephosphorization slag with low basicity.The characteristics of high basicity converter slag have been reported widely.However,the investigations on the low basicity slag properties for dephosphorization in converter are less discussed in steelmaking slag system.This study focused on the microstructure and phosphorus-containing phases in converter slag.The slag composition and mineral phase were examined by the usual XRF chemical analysis and EPMA,XRD studies.The results indicated that the phosphorus-containing phase in high basicity slag was the dicalcium silicate(2CaO·SiO_2 or C_2S) phase,while phosphorus in low basicity slag was incorporated in CaFeSiO_4 structure.

Design and experiment on concentration of phosphorus in factory converter slags

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 SiO_2 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 (C_2S) and tricalcium silicate(C_3S) 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 C_2S(Pconcentrating phase) in which the contents of P_2O_5 reach to 7.74%.This lays a good foundation for grinding and separation of P- concentrating phase.

Chemical Corrosion Mechanisms of Magnesite-chrome Bricks by Converter Slag

The corrosion resistance of four kinds magnesitechrome bricks against converter salg was investigated by static crucible slag tests. The microstructures of the asdelivered and tested refractories were analyzed by means of SEM and EDS. The results showed that： Different magnesite-chrome bricks have different slag resistances. Generally, the slag resiantance sequence is as follows： rebounded fused magnesite-chrome brick 〉 semi-reboun- ded magnesite-chrome brick 〉 direct-bonded magnesitechrome brick 〉 silicate bonded magnesite-chrome brick. Slag reacts with the periclase of magnesite-chrome refractories, which results in the dissoving of periclase in fayalite slag. However, the complex spinels have superior slag resistance.

High Efficient Technology of Steelmaking With Low Silicon Hot Metal on Large Converter

To resolve the difficulty in slag formation during steelmaking with low silicon hot metal and to increase productivity, a new 5-hole lance was developed by increasing oxygen flow from 50 000 m^3/h to 60 000 m^3/h. Synthetic slag was added to adjust the slag composition. The problems such as difficulty in dephosphorization and slag adhesion to oxygen lance and hood were settled. Steel production and metal yield were increased and the nozzle life was prolonged through these techniques.

Study on the optimization of the combined blown converter process in Chongqing Iron and Steel Company

The effects of lance height and bottom blown flowrate on the mixed time, the splashing amount, the penetrating depth, and the level fluctuation of an 85 t combined blown converter have been studied using a water model. The results show that the maximal stirring energy is provided to the bath at the top lance height of about 50-100 mm. When the top lance height is in the range ofg0- 110 mm, the splashing amount caused by the top jet can reach the maximal value. The appropriate operational parameters of Chongqing Iron and Steel Company （CISC） converter have been established that the top lance height is 1600-1760 mm and the bottom blowing flowrate is 240-480 Nm^3/h in the primary phase of a heat, 1100-1300 mm and 160-200 Nm^3/h in the second phase, and 1040-1120 mm and 200-350 Nm^3/h in the end phase. Also, the trial shows that the metallurgical result of the studied blow pattern is better than that of the former pattern. At the starting 3-4 min of a heat, the strong splashing is eliminated. 2008 University of Science and Technology Beijing. All rights reserved.

A Novel Method of Recycling CO_2 for Slag Splashing in Converter

Converter off-gas, an important energy resource for steel industries, is one of the weak points in the recov ery and utilization of secondary energy resources. To improve the level of recycling converter off-gas in steel plants, a novel approach to the recycle of CO2 separated from converter off-gas or other off-gas for the green slag splashing technique was developed, and the CO2 equilibrium conversion ratio of the green CO2 slag splashing under different technological conditions was calculated by the program of enthalpy （H）, entropy （S）, and heat capacity （C）, i.e. HSC software. Furthermore, the experiments of CO2 injected into molten converter slag were carried out, and the influencing factors of the green slag splashing technique using CO2 were analyzed. The experimental results showed that the carbon content for smooth slag splashing using COs was about 4.0%.

Leaching behavior and microstructure of phosphorus in converter slag

Converter slag is a by-product of the steelmaking process and contains a large amount of Ca,Fe,P and other elements.If the phosphorus in the converter slag can be effectively extracted,the resulting phosphorus can be used as a phosphate fertilizer.Phosphorus in converter slag is mainly enriched in 2CaO·SiO_(2)-3CaO·P_(2)O_(5)(C_(2)S-C_(3)P)solid solution and is easily dissolved in water.Therefore,acid leaching method was used to dissolve the solid solution to extract phosphorus in converter slag,so as to realize the recycling of phosphorus resources in converter slag.The leaching behavior of three actual converter slags from different steel mills in acid leaching solutions composed of citric acid,sodium hydroxide,hydrochloric acid and deionized water was studied by X-ray diffraction,scanning electron microscopy combined with energy dispersive spectrometry,Fourier transform infrared spectroscopy and Raman spectroscopy to reveal the change in object image structure as well as SiO_(4) and PO_(4) tetrahedron before and after acid leaching.The results show that only a small amount of phosphorus in converter slag with too low basicity is enriched in C_(2)S-C_(3)P solid solution,resulting in poor leaching effect.When the converter slag has a high basicity,the removal effect of phosphorus is 70.64%-81.88%.In addition,when the basicity of converter slag is roughly the same,the dephosphorization effect of slag with high FeO content is relatively poor.And acid leaching will cause depolymerization behavior of SiO_(4) and PO_(4) tetrahedron,so that the mole fraction of Q0(Si)(asymmetric stretching vibration of Si-O bond in SiO_(4) tetrahedron with bridge oxygen number of 0)and NBO/Si(non-bridging oxygen in silicate tetrahedra)will increase.Phosphate-containing solids can be obtained from the solution after acid leaching through static precipitation,and the solids have the potential to make phosphate fertilizers.

Melting Characteristics of Recycling Slag in Decarburization Converter and Its Application Effects

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.