Effect of the CaO/SiO_2 mass ratio and FeO content on the viscosity of CaO–SiO_2–“FeO”–12wt%ZnO–3wt%Al_2O_3 slags

An effective process for recycling lead from hazardous waste cathode ray tubes(CRTs) funnel glass through traditional lead smelting has been presented previously. The viscous behavior of the molten high lead slag, which is affected by the addition of funnel glass, plays a critical role in determining the production efficiency. Therefore, the viscosities of the CaO–SiO_2–"FeO"–12wt%ZnO–3wt%Al_2O_3 slags were measured in the current study using the rotating spindle method. The slag viscosity decreases as the CaO/SiO_2 mass ratio is increased from 0.8 to 1.2 and also as the FeO content is increased from 8wt% to 20wt%. The breaking temperature of the slag is lowered substantially by the addition of FeO, whereas the influence of the CaO/SiO_2 mass ratio on the breaking temperature is complex. The structural analysis of quenched slags using Fourier transform infrared(FTIR) spectroscopy and Raman spectroscopy reveals that the silicate network structure is depolymerized with increasing CaO/SiO_2 mass ratio or increasing FeO content. The [FeO_6]-octahedra in the slag melt increase as the CaO/SiO_2 mass ratio or the FeO content increases. This increase can further decrease the degree of polymerization(DOP) of the slag. Furthermore, the activation energy for viscous flow decreases both with increasing CaO/SiO_2 mass ratio and increasing FeO content.     

Effect of Al_2O_3 on the viscosity of CaO–SiO_2–Al_2O_3–MgO–Cr_2O_3 slags

We investigated the effect of Al_2O_3 content on the viscosity of CaO–SiO_2–Al_2O_3–8wt%MgO–1wt%Cr_2O_3 (mass ratio of CaO/SiO_2is 1.0,and Al_2O_3 content is 17wt%–29wt%) slags.The results show that the viscosity of the slag increases gradually with increases in the Al_2O_3content in the range of 17wt%to 29wt%due to the role of Al_2O_3 as a network former in the polymerization of the aluminosilicate structure of the slag.With increases in the Al_2O_3 content from 17wt%to 29wt%,the apparent activation energy of the slags also increases from 180.85 to 210.23 k J/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 Al_2O_3.The application of Iida’s model for predicting the slag viscosity in the presence of Cr_2O_3 indicates that the calculated viscosity values fit well with the measured values when both the temperature and Al_2O_3 content are at relatively low levels,i.e.,the temperature range of 1673 to 1803 K and the Al_2O_3 content range of 17wt%–29wt%in CaO–SiO_2–Al_2O_3–8wt%MgO–1wt%Cr_2O_3 slag.     

Shear-thinning behavior of the CaO–SiO_2–CaF_2–Si_3N_4 system mold flux and its practical application

Satisfying the mold-flux performance requirements for high-speed continuous casting necessitates the development of a new non-Newtonian-fluid mold flux with shear-thinning behavior, i.e., a mold flux whose viscosity is relatively high under lower shear rates and relatively low under higher shear rates. In this work, a mold flux that exhibits shear-thinning behavior was developed by adding different amounts of Si_3N_4 to the CaO–SiO_2–CaF_2 mold flux. The shear-thinning behavior was investigated using a rotational viscometer. In addition, the microstructure of the newly prepared slags was studied by high-temperature Raman spectroscopy and X-ray photoelectron spectroscopy. The results showed that the mechanism of shear-thinning was attributable to a temporary viscosity loss caused by the one-way shear stress, whereas the corresponding magnitude of shear-thinning was closely related to the degree of polymerization(DP). Finally, the non-Newtonian fluid mold flux was used for laboratory casting tests, which revealed that the mold flux could reduce slag entrapment and positively affect the continuous casting optimization.     

Effect of the CaO/SiO2 mass ratio and FeO content on the viscosity of CaO-SiO2-“FeO”-12wt%ZnO-3wt%Al2O3 slags

An effective process for recycling lead from hazardous waste cathode ray tubes (CRTs) funnel glass through traditional lead smelting has been presented previously. The viscous behavior of the molten high lead slag, which is affected by the addition of funnel glass, plays a critical role in determining the production efficiency. Therefore, the viscosities of the CaO-SiO₂-"FeO"-12wt%ZnO-3wt%Al₂O₃ slags were measured in the current study using the rotating spindle method. The slag viscosity decreases as the CaO/SiO₂ mass ratio is increased from 0.8 to 1.2 and also as the FeO content is increased from 8wt% to 20wt%. The breaking temperature of the slag is lowered substantially by the addition of FeO, whereas the influence of the CaO/SiO₂ mass ratio on the breaking temperature is complex. The structural analysis of quenched slags using Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy reveals that the silicate network structure is depolymerized with increasing CaO/SiO₂ mass ratio or increasing FeO content. The[FeO₆]-octahedra in the slag melt increase as the CaO/SiO₂ mass ratio or the FeO content increases. This increase can further decrease the degree of polymerization (DOP) of the slag. Furthermore, the activation energy for viscous flow decreases both with increasing CaO/SiO₂ mass ratio and increasing FeO content.     

Bioactivity analysis of the Ta (V) doped SiO2–CaO–Na2O–P2O5 ceramics prepared by solid state sintering method

The main objective of the study was to control the degradation rate of material at a higher degradation rate improving the chemical stability of the material. Ta is known to have good chemical resistance, biocompatibility and show no adverse biological response. In the present study, SiO2–Na2O–CaO–P2O5 bioceramics with different Ta2O5 contents was prepared by solid state sintering method at 1000 °C. The as-sintered ceramics were subjected to immersion studies in stimulated body fluid (SBF) for 21 days under static condition and characterized by XRD, FTIR, SEM, and AAS. The findings of the research indicate that the addition of Ta2O5 controlled degradability, and all samples showed sufficient bioactivity.     

Investigation of the kinetic mechanism of the demanganization reaction between carbon-saturated liquid iron and CaF_2–CaO–SiO_2-based slags

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO–SiO_2–MgO–FeO–MnO–Al_2O_3–TiO_2–CaF_2 was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step(RCS) for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide(Mn O), the apparent activation energy of the demanganization reaction was estimated to be 189.46 k J·mol~(–1) in the current study, which indicated that the mass transfer of Mn O in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the "specific reaction interface"(SRI) value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.     

Evolution of ferronickel particles during the reduction of low-grade saprolitic laterite nickel ore by coal in the temperature range of 900–1250℃ with the addition of CaO–CaF_2–H_3BO_3

The method of producing ferronickel at low temperature(1250–1400℃) has been applied since the 1950s at Nippon Yakin Kogyo,Oheyama Works, Japan.Limestone was used as an additive to adjust the slag composition for lowering the slag melting point.The ferronickel product was recovered by means of a magnetic separator from semi-molten slag and metal after water quenching.To increase the efficiency of magnetic separation, a large particle size of ferronickel is desired.Therefore, in this study, the influences of CaO, CaF_2, and H_3BO_3 additives on the evolution of ferronickel particle at ≤1250℃ were investigated.The experiments were conducted at 900–1250℃ with the addition of CaO,CaF_2, and H_3BO_3.The reduction processes were carried out in a horizontal tube furnace for 2 h under argon atmosphere.At 1250℃, with the CaO addition of 10 wt% of the ore weight, ferronickel particles with size of 20 μm were obtained.The ferronickel particle size increased to 165μm by adding 10 wt% CaO and 10 wt% CaF_2.The addition of boric acid further increased the ferronickel particle size to 376 μm, as shown by the experiments with the addition of 10 wt% CaO, 10 wt% CaF_2, and 10 wt% H_3BO_3.     

2CaO·SiO2-3CaO·P2O5固溶体形成机理

在1300℃下,通过向CaO-SiO2-FetO-P2O5系熔渣中浸入固相CaO的方法,分析了CaO-SiO2-FetO-P2O5渣系与固相CaO间的反应过程,利用分子离子理论计算了炉渣中各组元的活度,研究了2CaO·SiO2-3CaO·P2O5固溶体的形成机理.研究结果表明,CaO-SiO2-FetO-P2O5渣系中组元主要是以2CaO·SiO2和3FeO·P2O5化合物的形态存在;当固相CaO和炉渣接触时,渣中的2CaO·SiO2首先在固相CaO表面析出并形成2CaO·SiO2固相层;随着CaO组元和3FeO·P2O5化合物向反应界面的不断扩散,生成了2CaO·SiO2-3CaO·P2O5和CaO-FeO固溶体.     

Activity coefficients of NiO and CoO in CaO–Al_2O_3–SiO_2 slag and their application to the recycling of Ni–Co–Fe-based end-of-life superalloys via remelting

To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni–Co–Fe-based end-of-life(EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO–Al_2O_3–SiO_2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO–Al_2O_3–SiO_2 slag. The activity coefficients of NiO and CoO in CaO–Al_2O_3–SiO_2 slag both show a positive deviation from Raoult's law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B =(%CaO)/(%SiO_2) = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.     

CaO—Al2O3—SiO2熔渣的作用浓度计算模型

根据相图和炉渣结构的共存理论，推导了ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２渣系作用浓度的计算模型，计算的ＮＣａＯ和ＮＳｉＯ２与相应的实测αＣａＯ和αＳｉＯ２基本符合，从而证明所得模型可以反映本渣系的结构本持。与此同时，还发现生成正硅酸盐（２ＣａＯ．ＳｉＯ２）的碱度因Ａｌ２Ｏ３的增加而变大的事实和本渣系有Σｎ较小的活跃部分。     

石墨还原CaO－SiO_2－Al_2O_3－FeO熔渣过程中泡沫化行为

石墨还原ＣａＯ－ＳｉＯ_２－Ａｌ_２Ｏ_３－ＦｅＯ熔渣过程中泡沫化行为黄宗泽，肖兴国，肖泽强，ＳＤ辛格在１４４０～１５３０Ｃ，通过Ｘ射线装置观测了石墨活原ＣａＯ－ＳＩＯ；－ＡＩ。Ｏ。－ＦｅＯ＄渣（ＣａＯ）／ＳＩＯ。一０·７５～１·５）中ＦｅＯ反应过程中?..     

Evolution of ferronickel particles during the reduction of low-grade saprolitic laterite nickel ore by coal in the temperature range of 900–1250℃with the addition of CaO–CaF2–H3BO3

The method of producing ferronickel at low temperature(1250–1400℃)has been applied since the 1950s at Nippon Yakin Kogyo,Oheyama Works,Japan.Limestone was used as an additive to adjust the slag composition for lowering the slag melting point.The ferronickel product was recovered by means of a magnetic separator from semi-molten slag and metal after water quenching.To increase the efficiency of magnetic separation,a large particle size of ferronickel is desired.Therefore,in this study,the influences of CaO,CaF₂,and H₃BO₃ additives on the evolution of ferronickel particle at≤1250℃were investigated.The experiments were conducted at 900–1250℃with the addition of CaO,CaF₂,and H₃BO₃.The reduction processes were carried out in a horizontal tube furnace for 2 h under argon atmosphere.At 1250℃,with the CaO addition of 10 wt%of the ore weight,ferronickel particles with size of 20μm were obtained.The ferronickel particle size increased to 165μm by adding 10 wt%CaO and 10 wt%CaF₂.The addition of boric acid further increased the ferronickel particle size to 376μm,as shown by the experiments with the addition of 10 wt%CaO,10 wt%CaF₂,and 10 wt%H₃BO₃.     

CaO—Al2O3—SiO2—H2O系废渣砖研制

废渣已成公害．其出路在于生产建筑材料。本文利用尾矿、粉煤灰、碱渣等工业 废料通过掺配Ｃａ（ＯＨ）_２和外加剂，采用加压成型和蒸养工艺．研制出废渣砖．文 中还分析了ＣａＯ—Ａｌ_２Ｏ_３—ＳｉＯ_２—Ｈ_２Ｏ系废渣砖合成机理，以及影响其抗冻性的主要 因素。     

SiO2—TiO2—BaO—CaO耐碱涂层

以溶胶－凝胶浸涂工艺制备ＳｉＯ２－ＴｉＯ２－ＢａＯ－ＣａＯ头凝胶涂层。     

Preparation of Al2O3–SiO2 composite aerogels and their Cu2+absorption properties

In order to remediate heavy metal ions from waste water,Al2O3–SiO2 composite aerogels are prepared via a sol–gel and an organic solvent sublimation drying method.Various characterisation techniques have been employed including X-ray diffraction(XRD),Fourier transform infrared spectrometry(FTIR),scanning electron microscope(SEM),Energy-dispersion X-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)N2 adsoprtion isotherm,and atomic absorption spectrometer(AAS).XRD and FTIR suggest that the aerogels are composed of mainly Al2O3 and minor SiO2.They have a high specific surface area(827.544 m^2/g)and high porosity(86.0%)with a pore diameter of~20 nm.Their microstructures show that the distribution of Al,Si,and O is homogeneous.The aerogels can remove~99%Cu^2+within~40 min and then reach the equilibrium uptake(~69 mg/g).Preliminary calculations show that the Cu2+uptake by the aerogels follows pseudo second-order kinetics where chemical sorption may take effect owing largely to the high surface area,high porosity,and abundant functional groups,such as Al–OH and Si–OH,in the aerogel network.The prepared aerogels may serve as efficient absorbents for Cu^2+removal.     

CaO—SiO2系统溶胶凝胶过程及其机理

以下硅酸乙酯，醋酸钙等为原料，采用溶胶凝胶工艺制备了ＣａＯ－ＳｉＯ２系统湿弟胶。研究了其溶胶凝胶化过程中溶胶粘度变化及溶胶粒子的生长过程，以及湿凝胶在干燥过程中的析晶现象，并对其机理进行了探讨。     

CaO,SiO,Al2O3和MgO四元渣系脱硫

根据石钢生产条件,研究了ＣａＯ、ＳｉＯ２、Ａｌ２Ｏ３和ＭｇＯ四元渣系脱硫性能,实验结果表明：炉渣碱度在１．１０－１．２０之间,ＭｇＯ≯１０％,Ａｌ２Ｏ３≯１５％时能获得最佳的脱硫效果。     

Phosphate enrichment mechanism in CaO–SiO2–FeO–Fe2O3–P2O5 steelmaking slags with lower binary basicity

The addition of silica to steelmaking slags to decrease the binary basicity can promote phosphate enrichment in quenched slag samples. In this study, we experimentally investigated phosphate enrichment behavior in CaO–SiO₂–FeO–Fe₂O₃–P₂O₅ slags with a P₂O₅ content of 5.00% and the binary basicity B ranging from 1.0 to 2.0, where the (%Fe_tO)/(%CaO) mass percentage ratio was maintained at 0.955. The experimental results are explained by the defined enrichment degree R_C2S-C3P of solid solution 2CaO·SiO₂–3CaO·P₂O₅ (C₂S–C₃P), where R_C2S-C3P is a component of the developed ion and molecule coexistence theory (IMCT)–N_i model for calculating the mass action concentrations N_i of structural units in the slags on the basis of the IMCT. The asymmetrically inverse V-shaped relation between phosphate enrichment and binary basicity B was observed to be correlated in the slags under applied two-stage cooling conditions. The maximum content of P₂O₅ in the C₂S–C₃P solid solution reached approximately 30.0% when the binary basicity B was controlled at 1.3.     

Effect of sintering on the optical properties of SiO2 colloidal crystal multilayers

High-quality SiO2 colloidal crystal multilayers were fabricated from ethanol solutions by the vertical deposition method and the effect of sintering on the optical properties of the samples was investigated. Optical properties,which are determined by the photonic band structure, weres tudied by means of light transmission and reflection measurements. The morphology of the samples was characterized by scanning electron microscopy (SEM). SEM images illustrate the ordered close package of the spherical colloids in planes parallel to the substrate surface. In addition, the sampie is crackless as a result of an appropriate drying rate. It is shown that with the increase of the sintering final temperature, though the depth and the width of the peak of Bragg diffraction of the sample vary vastly, the peak produces few blue shifts. Optical measurement results were compared favorably to the microstructural properties of the colloidal crystal multilayers.