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Operational performance of ironmaking processes is determined to a great extent by its slag viscosity. A simple and accurate viscosity model for blast furnace (BF) slags has been developed based on the Urbain model using the critically evaluated experimental data reported by the authors and other researchers. A total number of 2958 viscosity measurements from 582 compositions in the SiO2-Al2O3-CaO-MgO system have been collected from 34 publications. These data have been critically reviewed for developing a viscosity model for ironmaking slags. The model has been significantly revised by consideration of alumina behavior in this system and re-optimization of the parameters using large quantity and high quality data. The new model has less number of parameters, but better performance in the viscosity predictions. Applications of the new viscosity model on BF operation have been discussed. [ABSTRACT FROM AUTHOR]

Phase equilibria of the ' Cu2 O'- Al2 O3- SiO2 system have been experimentally investigated at metallic copper saturation. High-temperature equilibration, rapid quenching, and electron probe X-ray microanalysis ( EPMA) techniques have been used. Containerless equilibration technique has been developed to enable the phase equilibrium of this chemically reactive system to be investigated. The microstructures and compositions of all phases present in the quenched sample were measured accurately using EPMA. The isothermals between 1150°C and 1300°C have been determined in the ' Cu2 O'- Al2 O3- SiO2 system at metallic copper saturation. The following primary phase fields were identified in the system: SiO2 (tridymite), Cu2O (cuprite), Cu2 O. Al2 O3 (delafossite), Al2 O3 (corundum), and 3 Al2 O3·2 SiO2 (mullite). The implications of the phase diagram on making of the copper aluminosilicate glass have been demonstrated. [ABSTRACT FROM AUTHOR]

The present study investigated phase equilibria in the Na2O-SiO2-WO3 system experimentally using high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA). New thermodynamic information on the Na2O-SiO2-WO3 system was derived based on the newly obtained experimental results and data from the literature. The primary phase fields of sodium metasilicate, sodium disilicate, and tridymite were determined along with the isotherms at 1073, 1173, and 1273 K. The solubilities of WO3 in SiO2, Na2Si2O5, and Na2SiO3, and the solubility of SiO2 in Na2WO4 were accurately measured using EPMA. Comparisons between the existing and newly constructed phase diagram were carried out and the differences are discussed. The phase equilibrium data will be beneficial to the future development of sustainable tungsten industries and thermodynamic modelling in WO3 related systems. [ABSTRACT FROM AUTHOR]

• From the two-layer quasi-geostrophic potential vorticity equations with dissipative effect, we get a new two-layer fluid model with dissipation effects by using perturbation expansion method. • We analyze the nonlinear stability by energy method of Serrin. The existence of sheared zonal flow can be an important factor in generating external energy, and is one of the causes of disturbance solitary waves. • Some exact solutions of the two-layer equations are obtained by using the Jacobi elliptic function expansion method. We know that the existence of the scalar nonlinearity will lead to uneven development of the Rossby vortices with different polarities, and the scalar non-linearity can reduce the threshold of disturbance energy increase. In this paper we investigate the instability of two-layer quasi-geostrophic model with scalar nonlinearity, which is a geophysical fluid dynamics model, and give a nonlinear stability criterion. Furthermore, the analytical solutions of the two-layer quasi-geostrophic model are obtained via the Jacobi elliptic periodic function transform method and symbolic computation. It is efficient in solving a range classes of nonlinear partial differential equations for this method. The result shows that the structure of Rossby waves is influenced by many factors such as base flow and scalar nonlinearity. [ABSTRACT FROM AUTHOR]

Carbon reductant used in metallurgy industry is a considerable source of carbon dioxide emissions. Growing concerns over greenhouse effect have urgently prompted research in the application of hydrogen energy as an alternative. However, some basic kinetic problems in the hydrogen reduction process have not been clarified and resolved yet, such as the activation energy fluctuations caused by neglect of pore characteristics, along with the overly subjective division of the whole reaction process to analyze rate limiting mechanisms. In this study, a novel approach for acquiring instantaneous activation energy is proposed that is able to identify the activation energy at every reaction moment and thereby provide a quantitative basis for kinetics segmentation and rate-limiting mechanism determination. Moreover, due to the space requirements, the activation energy for the reaction stage controlled by nucleation and nuclei growth has a strong correlation with specific surface area. Whereas the restriction mechanisms of chemical reaction and diffusion are closely related to the average pore size. These results reveal that the different pore characteristics and changes in value have a direct influence on the corresponding rate limiting mechanisms and restriction degrees. • Instantaneous activation energy is proposed to quantitatively divide reaction. • Model-fitting and iso-conversion are combined to determine kinetic mechanism. • Porosity and temperature play a major role in rates at initial and mid-late stages. • Activation energy of nucleation and nuclei correlates with specific surface area. • Activation energy of chemical reaction and diffusion are related to average pore size. [ABSTRACT FROM AUTHOR]

Effects of TiO 2 , binary basicity and MgO content on the liquidus temperatures of TiO 2 –CaO–SiO 2 –MgO–Al 2 O 3 slags were experimentally studied in equilibrium with carbon. The experimental techniques include high temperature equilibration, quenching and Electron Probe X-ray Microanalysis (EPMA). It was found that the major primary phase in the composition range investigated is M 3 O 5 (M = Ti, Mg, Al). The liquidus temperatures increase with increasing TiO 2 and MgO contents, whereas decrease with increasing CaO/SiO 2 mass ratio. The experimentally determined liquidus temperatures are much higher than the predicted ones by FactSage and the primary phases between the experiment results and predictions are also different. The mole fractions of Al 2 TiO 5 and Ti 3 O 5 in the M 3 O 5 phase decrease, but MgTi 2 O 5 increases with increasing MgO content and CaO/SiO 2 in the samples. Moreover, the proportions of Al 2 TiO 5 and MgTi 2 O 5 in the M 3 O 5 phase decrease, while Ti 3 O 5 proportion in the M 3 O 5 phase increases with increasing the reaction time. The mole ratio of Ti3+/Ti4+ in the M 3 O 5 phase decreases with MgO content and CaO/SiO 2 mass ratio in the samples but increases with increasing reaction time. [ABSTRACT FROM AUTHOR]

Iron oxides and silica are the major components of copper smelting slag. The oxides of aluminum, calcium and magnesium are also present in the slag that is introduced through copper concentrate, flux and refractories. Liquidus temperatures of the copper smelting slags are usually controlled by Fe/SiO 2. The concentrations of Al 2 O 3 , CaO and MgO, and FeO/Fe 2 O 3 in the slag can also affect the liquidus temperatures where FeO/Fe 2 O 3 is a function of oxygen partial pressure. High temperature equilibration under controlled oxygen partial pressure followed by quenching and electron probe microanalysis were used to determine the compositions of the liquid and solid phases at 1200 °C and Po 2 10-8 atm. The experimental results are presented in the forms of pseudo-ternary sections "FeO"-CaO-SiO 2 at fixed 2, 4 and 6 wt pct MgO, and 2 + 2, 4 + 4 and 6 + 6 wt pct MgO + Al 2 O 3. Spinel and tridymite are the major primary phases in the composition range investigated. In addition, CaSiO 3 , pyroxene, olivine, and melilite are also present. The isotherms in the spinel and tridymite primary phase fields move towards higher SiO 2 concentration directions with increasing CaO, Al 2 O 3 , and MgO concentrations. The experimentally determined results are compared with the FactSage calculations. [ABSTRACT FROM AUTHOR]

• Diatomite was used to partially replace cement for improving the RAC performance. • Both strength and impermeability of RAC were greatly enhanced. • Nucleation effects and the high pozzolanic reactivity of diatomite contributed to more complete cement hydration in RAC. • The large pores in new mortar and the average porosity of new ITZ were reduced. • The replacement of cement by diatomite is suggested to be no larger than 15 wt%. This work proposes that diatomite can be used to improve the performance of recycled aggregate concrete (RAC). A calcined diatomite sample with an amorphous silica content over 90% was added to the RAC mixture as a partial replacement of the ordinary Portland cement (OPC) at varying rates from 0 to 20 wt%. Test results show that both the strength and impermeability of RAC can be obviously enhanced with the greatest enhancement observed at a replacement level of 15 wt% for which the 28-day compressive/splitting tensile strengths were improved by 29.2% and 33.9%, respectively, and the chloride diffusion coefficient was reduced by 86.27%. The microscopic measurements confirmed the nucleation effects and the high pozzolanic reactivity of diatomite which both contributed to the more complete hydration of cement in RAC. It was also found that the proportion of large capillary pores in the new mortar was reduced by using diatomite, meanwhile the average porosity of the new interfacial transition zone (ITZ) became smaller. This work suggests that the calcined diatomite used for improving RAC performance should be no larger than 15 wt% of cement, as the scarcity of CH at a higher replacement ratio would hamper the pozzolanic reactions, meanwhile the diluted cement clinkers would have a negative effect on the pore structure of RAC. [ABSTRACT FROM AUTHOR]

The paper study the shear bearing performance and failure mechanism of perfobond leiste (PBL) shear connectors after hydrochloric acid corrosion. Seven groups of specimens with PBL shear connectors were designed, these PBL shear connectors suffered from hydrochloric acid corrosion time of 0 h, 1 h, 4 h, 12 h, 24 h, 48 h and 72 h. Herein, loading process, shear bearing capacity, load-slip curve, and failure mode were obtained by the push-out experiment, and then refined the finite element model (FEM) was established. Following the parameter analysis of 14 experiment specimens and 77 finite element models, the force mechanism of PBL shear connectors after hydrochloric acid corrosion were analyzed. With the extension of the corrosion time of PBL shear connectors, the shear capacity, deformation capacity, and slip decrease gradually. Among them, the finite element parameter analysis of PBL shear connectors demonstrates that their shear bearing capacity has the ability to be modified by raising the concrete strength, the diameter of penetrated steel bar, the diameter of steel plate holes, and changing the end bearing mode. On condition that the concrete strength is raised from C30 to C60, the shear capacity is reduced by 5.19%. When the diameter of penetrated steel bar has mushroomed from 12 mm to 25 mm, the shear capacity declines by 9.59%. Meanwhile, the shear bearing capacity of the end bearing is about 2 times of the non-end bearing. Once the diameter of steel plate holes adds 35 mm to 65 mm, the shear capacity just decreases by 2.48%. Finally, the reliability of PBL shear connectors are analyzed by the exit experiment data and the shear bearing capacity formula of PBL shear connectors. The research results can offer a reference for the shear bearing capacity of PBL shear connectors after hydrochloric acid corrosion. [ABSTRACT FROM AUTHOR]