Volume 36, Issue 6 -

The knowledge of redox equilibria of iron in multicomponent molten slags is of significant importance to understand the viscosity, electrical conductivity and structure of iron-containing slags. However, the available data of molar ratio of ferric ion to ferrous ion are limited due to the difficulty of experiment and heavy workload. In this study, a model was established to estimate the XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ (normally, most of ferric ions exist in the form of complex anions such as FeO2−$${\rm{FeO}}_2^ - $$) ratio in CaO–MgO–Al 2 O 3 –SiO 2 –“FeO t ” slags, which can give good estimation results compared to the experimental measured values. From the model, by increasing oxygen partial pressure or decreasing temperature, the XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio will increase. Different components have different influences on XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio: CaO and MgO are beneficial for the increase of this ratio, but Al 2 O 3 and SiO 2 have reverse effects.

The creep properties of GH3536 nickel-based superalloy plate specimens without/with multi-inclined holes were studied under applied stress 80/90/100 MPa at 850 ℃, respectively. Interesting finding is focused on the inflection point, that is, both the fraction elongation and creep strain achieve the maximum value under 90 MPa. Further study is carried out by two methods: the finite element analysis (FEA) calculation and scanning electron microscope (SEM). The FEA results show that the dangerous areas appear in the regions near the end of ellipse axis along the inclined angle orientation, which is similar to the actual fracture appearances. What is more, the tiny holes and dimples are the main characters of creep fracture for multi-inclined hole specimens, whereas the creep fracture of specimens without holes is the result of growth and coalescence of voids. In addition, based on creep performance, laser drilling is better than that of the electric spark drilling, which provides a proof that the creep performance of specimens with multi-inclined holes will be better with the improvement of the drilling process.

In consideration of great need for the physicochemical properties of slag systems in metallurgical process estimation, this work examined the possibility of predicting multi-properties by one model. The mass triangle model was applied to evaluate the density, viscosity, surface tension and sulfide capacity of CaO–“FeO”–SiO 2 system at 1,673 K. Good agreements were achieved between calculated data and experimental data in the various properties. Meanwhile, the calculated contour lines successfully predicted the properties of slag within the limited solubility area. The new model thus is competitive and flexible when an integrated knowledge of a certain system is necessary.

A novel process for the treatment of zinc sulfide ores is discussed in this paper, which consists of two procedures: microwave roasting pretreatment and synergistic chelation. What’s more, the reaction mechanism also has been studied. By comparing XRD patterns before and after roasting, it can be concluded that microwave truly alleviates the reaction energy, and adding Na 2 O 2 avoids the emission of SO 2 . % recovery of zinc can reaches 72.47 % on conditions of adding Na 2 O 2 25 %, microwave activating temperature 500 °C, holding time 10 min, leaching temperature 40 °C, ultrasonic wave power 1,800 W, leaching time 4.5 h and solid to liquid ratio 10:1 in ammonium chloride solution whose total ammonium concentrate is 7.5 mol/L (c(NH 3 ) T =7.5 mol/L). The molar ratio of NH 4 Cl and NH 3 ·H 2 O is 1:1 (c(NH 4 Cl): c(NH 3 ·H 2 O)=1:1). The effect of ultrasonic wave power in this process is to shorten reaction time.

High-current pulsed electron beam (HCPEB) technique was applied to irradiate the surface of mono-crystalline silicon wafers. Surface microstructures of the irradiated surface were investigated in detail by atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The experimental results show that HCPEB irradiation with energy density 4 J/cm 2 caused evaporation of the irradiated surface. Subsequently, the evaporation Si-droplets was deposited to form Si-nanoparticles on the surface. Meanwhile, the structures of intensive plastic deformation were also introduced within the irradiated surface layer. The dislocation configurations with rectangular and approximate hexagonal network were formed on the surface of Si wafer after 5-pulsed irradiation. The periodic self-deposited structures appear to be related to the configuration of regular dislocations arrays, which were favorable locations for the deposited Si-nanoparticles.

A 3D transient numerical model of dephosphorization kinetics coupled with flow field in a top blown converter was built. Through the model the dephosphorization reaction rate influenced by the oxygen jets and the steel flow were simulated. The results show that the dephosphorization rate at the droplet metal–slag interface is two orders of magnitude faster than that at bath metal–slag interface. When the lance oxygen pressure increases from 0.7 to 0.8 MPa, the dephosphorization rate increases notably and the end content of P has a decrease of 19 %. However, when the pressure continues rising to 0.9 MPa, the dephosphorization rate has no significant increase. In addition, the lance height shows a nearly linear relation to the end P content of steel, that the lower the height, the faster the dephosphorization rate.

To solve the environmental pollution problem caused by low-grade silica fume (SiO 2 , < 86 mass%) and further expand its application field, the morphological development of low-grade silica fume from room temperature to 900 °C in air was investigated using TG-DTA, SEM and TEM techniques. The structural development of silica fume was further analyzed using FT-IR and Raman spectrum. The results show that silica fume contains many defects of broken bands such as Si-O or ≡Si at room temperature. When exposed to the moister or water, the broken bonds tend to react with water and result in the formation of Si-OH and adjacent hydroxyl groups of Si-OH•OH-Si. At elevated temperature up to 900 °C, the structure of silica fume becomes compact due to the reconstruction of the broken bonds caused by the dehydration reaction.

As the cost of hot metal is reduced for iron ore prices are falling in the international market, more and more electric arc furnace (EAF) steelmaking enterprises use partial hot metal instead of scrap as raw materials to reduce costs and the power consumption. In this paper, carbon emissions based on 1,000 kg molten steel by charging hot metal in EAF steelmaking is studied. Based on the analysis of material and energy balance calculation in EAF, the results show that 146.9, 142.2, 137.0, and 130.8 kg/t of carbon emissions are produced at a hot metal ratio of 0 %, 30 %, 50 %, and 70 %, while 143.4, 98.5, 65.81, and 31.5 kg/t of carbon emissions are produced at a hot metal ratio of 0 %, 30 %, 50 %, and 70 % by using gas waste heat utilization (coal gas production) for EAF steelmaking unit process. However, carbon emissions are increased by charging hot metal for the whole blast furnace–electric arc furnace (BF–EAF) steelmaking process. In the condition that the hot metal produced by BF is surplus, as carbon monoxide in gas increased by charging hot metal, the way of coal gas production can be used for waste heat utilization, which reduces carbon emissions in EAF steelmaking unit process.

Determining the mechanical properties of particleboard has gained a great importance due to its increasing usage as a building material in recent years. This study aims to develop artificial neural network (ANN) and multiple linear regression (MLR) models for predicting modulus of rupture (MOR) and modulus of elasticity (MOE) of particleboard depending on different pressing temperature, pressing time, pressing pressure and resin type. Experimental results indicated that the increased pressing temperature, time and pressure in manufacturing process generally improved the mechanical properties of particleboard. It was also seen that ANN and MLR models were highly successful in predicting the MOR and MOE of particleboard under given conditions. On the other hand, a comparison between ANN and MLR revealed that the ANN was superior compared to the MLR in predicting the MOR and MOE. Finally, the findings of this study are expected to provide beneficial insights for practitioners to better understand usability of such composite materials for engineering applications and to better assess the effects of pressing conditions on the MOR and MOE of particleboard.

The silicate-type and Eu 3+ -activated Sr 3 SiO 5 and Mg 3 SiO 5 were prepared through the high temperature solid state reaction method under an open atmosphere. DTA/TG analysis was conducted to obtain information about the thermal behaviors of the mixed reactants. Using the DTA/TG results, the sintering process was achieved and the phase properties were characterized by X-ray diffraction (XRD). The effects of the same activator (Eu 3+ ) and co-dopant (Dy 3+ ) on the photoluminescence (PL) properties of the host lattices were investigated by using a photoluminescence spectrometer.

Composite molecular sieve Y/SBA-15(C-Y) was prepared by microwave method, while Ce was loaded by ion exchange method to the composite molecular sieves (Ce-Y/SBA-15 (C-X)). Productive-type middle distillate hydrocracking catalyst was prepared from C-X and C-Y loaded. FI-IR, XPS, Pyridine IR, and TG-DTG had been used to characterize the C-X’s and C-Y’s structure and acidity. The results showed that Ce loaded not only had not broken the original structure of C-Y, but also improved silica alumina ratio of C-X, furthermore improved its total acid content. Through polarization and entrainment, Ce increased the skeleton and hydroxyl silicon aluminum hydroxy on electronic probability of migration to the cage, thus enhance the C-X’s B acid strength, make it more suitable for heavy oil processing. As compared with C-Y, the selectivity and yield of middle distillates over C-X was 0.7 % and 1.8 % higher, respectively. C-X have the greatest relief wax oil viscosity index, best once cracking selectivity, and lowest levels of diesel oil solidifying point in the three catalysts.