International Journal of Minerals, Metallurgy and Materials

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Lei Shao, Rolf A. Kleiv, Kunt L. Sandvik, Cunyi Song, Shouci Lu

2000, 7(4): 237-241.

中文摘要(274) PDF(10) SpringerLink

摘要:
Copper adsorption on olivine supplied by the A/S Olivine Production Plant at Aheim in western Norway was studied. The factors were evaluated which affect the uptake of copper. It is shown that the equilibrium pH of aqueous solution has the greatest influence on copper adsorption thanks to the competitive adsorption between proton and copper ions, and the adsorption of copper to olivine increases rapidly with pH increasing from 4 to 6. Moreover, initial copper concentration and olivine dose possess significant effect on copper adsorption, for the adsorption rate of copper increases with olivine dose increasing or initial copper concentration decreasing at the same pH. In addition, the ionic strength effect on the adsorption was also investigated, but it owns little effect on the adsorption process of copper due to the formation of inner sphere adsorption of copper on olivine. The experimental data show that olivine has a high acid buffer capacity and is an effective adsorbent for copper.

Metallurgy

Effect of Process Factors on Microstructure of Semisolid Continuous Casting Billets

Shuming Xing, Qijie Zhai, Hanqi Hu

2000, 7(4): 242-245.

中文摘要(277) PDF(9) SpringerLink

摘要:
Semisolid continuous casting (SSCC) is a new technology to produce billets for semisolid metal forming (SSMF). The effect of process factors, such as pouring temperature, stirring rate, preheating temperature and thermal conductivity of stirring chamber, on the microstructure of SSCC billets was studied by means of the factorial experimental method. The results show that the microstructure of SSCC billets can be controlled by the above-mentioned four process factors. In order to obtain fine and rounded granular grains in an SSCC billet, the pouring temperature, preheating temperature and stirring rate should be kept in a moderate range, and the thermal conductivity of stirring chamber should be high. The regression equations with the process factors connecting the microstructure was also set up based on experimental data.

Metallurgy

Calculating Models of Mass Action Concentrations for Ni-Mn and Co-Mn Melts and Optimization of Their Thermodynamic Parameters

Jian Zhang

2000, 7(4): 246-250.

中文摘要(223) PDF(7) SpringerLink

摘要:
According to phase diagrams, measured activities as well as the coexistence theory of motallic melts structure involving compound formation, the calculating models of mass action concentrations for Ni-Mn and Co-Mn melts are formulated and their thermodynamic parameters are optimized. As a result, the calculated mass action concentrations agree well with the corresponding measured activities, showing that these models can reflect the structural characteristics of both Ni-Mn and Co-Mn melts.

Metallurgy

Oxidizing Capability of Refining Slags Containing BaO

Gang Lu, Guoguang Cheng, Bo Song, Pei Zhao

2000, 7(4): 251-255.

中文摘要(241) PDF(7) SpringerLink

摘要:
According to the coexistence theory of slag structure melts, the oxidizing capability of the refining slag CaO-MgO-FeO-Al₂O₃-SiO₂ is studied and the relationship between the mass action concentration of FeO (N_FeO) and the activity of Fe_tO (α_{Fe_tO}) for this slag is found to be as N_Feo=0.656 1 α_{Fe_tO}. Furthermore, the calculating model of oxidizing capability of the refining slag BaO-CaO-MgO-FeOAl₂O₃-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.

Metallurgy

Agglomeration Mechanism of Rich Hematite Sinter with Lowering SiO₂ Content

Dongping Duan, Yibo Gong, Ju Wang

2000, 7(4): 256-260.

中文摘要(272) PDF(11) SpringerLink

摘要:
The mini-sintering test was introduced. The experiments of specimens of rich hematite with lowering SiO₂ content were carried out by the mini-sintering test. The strength and mechanism of agglomeration were studied mainly when silica content in sintered specimens was decreased gradually. The relationships between SiO₂ volume and morphology of sinter were also investigated. It is considered that high grade sinter can be developed by raising sinter basicity so as to enhance complex calcium ferrite content or lowering sinter basicity so as to make Fe₂O₃ bonding for strength.

Metallurgy

Numerical Modeling of NO Formation during Packed-bed Combustion of Coke Granules

Chunbao Xu, Shengli Wu, Daqiang Cang

2000, 7(4): 261-268.

中文摘要(340) PDF(18) SpringerLink

摘要:
A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions), heterogeneous gas-solid chemistry (including 11 reactions) of coke combustion and NO formation, and the heat and mass transfer were taken into account in the present model. The governing equations which are strongly coupled, non-linear and unsteady with 26 unknowns in total, were dispersed into differential equations with the finite differential method. Meanwhile, all the differential equations were numerically solved to give the time-histories and space-distributions oftemperatures of the bed and gas phase as well as the concentrations of all the gaseous species. By comparison, the experimental data were explained well by the calculated results. Based on the kinetic and mathematical model, the effects of O₂ content of inlet gas, the initial chemical analysis of coke, bed-temperature and local reductive atmosphere (CO/O₂) on NO formation during packed-bed coke combustion were numerically discussed. It was found that coke samples with a higher initial content of [N] and volatile matters, combusted under a suitable O₂-containing atmosphere produced less NO emission. The reactions between CO and NO, catalyzed by high temperature surface of coke particles may be responsible for efficient reduction of NO.

Metallurgy

An Improved Artificial Neural Network Model for Predicting Silicon Content of Blast Furnace Hot Metal

Bin Yao, Tianjun Yang, Xiaojun Ning

2000, 7(4): 269-272.

中文摘要(262) PDF(11) SpringerLink

摘要:
Based on the skills of initializing weight distribution, adding an impulse in a neural network and expanding the ideal of plural weights, an artificial neural network model with three connection weights between one and another neural unit was established to predict silicon content of blast furnace hot metal. After the neural network was trained in the off-line state on the basis of a large number of practical data of a commercial blast furnace and making many learning patterns, satisfactory testing and simulating results of the model were obtained.

Metallurgy

Application of Gray Linear Programming in Sintering Mixing Calculation

Deling Zheng, Zhijiang Zhao, Wei Fang, Tong Fang

2000, 7(4): 273-276.

中文摘要(245) PDF(8) SpringerLink

摘要:
The mixing calculation cannot be restrained by the quantity of return mines. In order to solve this problem, a method that the sintering mixing proportion is optimized by gray linear programming is presented based on the gray system theory and optimal theory. By using this method, the quality of sintering mines is improved and the energy consumption is reduced.

Materials

Phase Equilibria in Ni Rich Region of Ni-Al-Fe System

Chengchang Jia, Kiyohito Ishida, Taiji Nishizawa

2000, 7(4): 277-281.

中文摘要(267) PDF(18) SpringerLink

摘要:
The phase equilibria between γ, α, γ' and β in the Ni-rich region of the Ni-Al-Fe system were investigated by the diffusion couple method and thermodynamic models. The thermodynamic parameters were assessed based on experimental results and thermodynamic data. Moreover, the system's phase equilibria from 900 to 1 300℃ were calculated with regular solution and sublattice models, and it is shown that the theoretic results agree well with experimental phase diagram data.

Materials

Structure and Composition of Crystalline Carbon Nitride Films Synthesized by Microwave Plasma Chemical Vapor Deposition

Yongping Zhang, Yousong Gu, Xiangrong Chang, Zhongzhuo Tian, Xiufang Zhang

2000, 7(4): 282-285.

中文摘要(278) PDF(11) SpringerLink

摘要:
Crystalline carbon nitride thin films were prepared on Si (100) substrates by a microwave plasma chemical vapor deposition method, using CH₄/N₂ as precursor gases. The surface morphologies of the carbon nitride films deposited on Si substrate at 830℃ are consisted of hexagonal crystalline rods. The effect of substrate temperature on the formation of carbon nitrides was investigated. X-ray photoelectron spectroscopy analysis indicated that the maximum value of N/C in atomic ratio in the films deposited at a substrate temperature of 830℃ is 1.20, which is close to the stoichiometric value of C₃N₄. The X-ray diffraction pattern of the films deposited at 830℃ indicates no amorphous phase in the films, which are composed of β- and α-C₃N₄ phase containing an unidentified C-N phase. Fourier transform infrared spectroscopy supports the existence of C-N covalent bond.

Materials

Physical and Electrochemical Properties of Acid 1-Methyl-3-Ethylimidazolium Chloride/AlCl₃/LiAlCl₄Molten Salt

Ying Sing Fung, Ruqi Zhou

2000, 7(4): 286-291.

中文摘要(349) PDF(12) SpringerLink

摘要:
An acid molten salt was formed by means of mixing 1-methyl-3-ethylimidazolium chloride with AlCl₃ and LiAlCl₄ at ambient temperature. The solubility of LiAlCl₄ in the acid molten salt was measured. Variations of specific conductivity, density and kinetic viscosity of molten salt with mole ratio of MeEtlmCl/AlCl₃/LiAlCl₄ were observed. A solubility maximum of LiAlCl₄ with 54% in molar fraction was shown at a mole ratio of AlCl₃/MeEtlmCl = 1.2. An increase in density and viscosity, and a decrease in specific conductivity were found with increasing the concentrations of LiAlCl₄ and AlCl₃. The dependence of specific conductivity of this acid molten salt upon temperature was found to display Vogel-Tammanm-Fucher behavior. However, Arrhenius behavior was observed at two special mole ratios of MeEtImCl/AlCl₃/LiAlCl₄ = 1:1.5:0.05 and 1. 1.5:0. 10. The conductivity equations of this molten salt at various compositions were constructed. The ion interaction in the acid molten salt was studied using ⁷Li and ²⁷Al nuclear magnetic resonance spectroscopic methods. The effect of concentrations of LiAlCl₄ and AlCl₃ on the ion interaction was also discussed.

Materials

Phenomenological Modeling of Warm Compaction and Experimental Verification

Shiju Guo, Tao Lin

2000, 7(4): 292-295.

中文摘要(234) PDF(7) SpringerLink

摘要:
A phenomenological modeling approach to establishing the warm compaction equation and curves by modifying the regression equation of the room-temperature compaction curve is presented. An enhanced factor of compacting pressure is introduced into the equation in order to reveal the effects of powder/die temperature and filling height of powders on green density. Compaction curves yielded from this equation are consistent with the experimental data of ATOMET grade iron powders. The curves show that the powder/ die temperature should reduce as the filling heights of powders increase and that in some cases warm compaction can not give rise to a higher green density.

Information

Mathematical Model for the Drying Process of Granular Materials in a Fluidized Bed

Xiulan Huai, Li Wang, Zhiyun Qu

2000, 7(4): 296-300.

中文摘要(277) PDF(10) SpringerLink

摘要:
The experiment of granular materials, barley, drying in a fluidized bed was carried out to investigate the influence of the factors, inlet air temperature, air moisture, bed height and original moisture content of the dried materials on drying process. Based on the experimental data, a corresponding mathematical model is presented. As a conclusion, a higher inlet air temperature and a reasonable bed height should be used so as to increase the dring rate and to improve the product quality.

Information

Mathematical Models of Logistics Decision in Slab Yard in an Iron and Steel Complex

Sujian Li, Zhiming Chan

2000, 7(4): 301-304.

中文摘要(269) PDF(8) SpringerLink

摘要:
The slab yard in a hot strip rolling mill is a key link and a buffer in the production system, which joins continuous rolling process and continuous casting process. There are a large quantity of operations of input and output in the slab yard. Throughout systematic analysis and research on the slab yard, the mathematical models of logistics decision for input, output and restorage operation are built. On the basis of these decision models, the management system for the slab yard is developed. Simulation application to Human Iron & Steel Complex of China shows that they are very effective.

Information

Analytical Criteria for Local Activity of CNN with Two-port and Application to Biochemical Model

Lequan Min, Na Yu

2000, 7(4): 305-314.

中文摘要(226) PDF(9) SpringerLink

摘要:
The analytic criteria are presented for the local activity theory in two-port Cellular Neural Network (CNN) cells with three local state variables, and the application to a Biochemical Model CNN (BMCNN) is given for coupling in series of two enzymes whose prototype was studied by Decroly and Goldbeter. The bifurcation diagrams of the BMCNN's show that there does not exist a locally passive domain, and the computer simulation exhibited that convergent patterns, oscillatory patterns or chaotic patterns may emerge if the selected cell parameters are located in locally active unstable domains but nearby the edge of chaos domain. In particular, the coexistence of multiple oscillations was observed in the corresponding triple cell couples of the BMCNN's with the same initial conditions.

Information

A WT-STFT combining Algorithm

Xisheng Li, Shaochun Wang

2000, 7(4): 315-317.

中文摘要(390) PDF(17) SpringerLink

摘要:
A fast wavelet packet (WP) algorithm is presented, in which the wavelet transform (WT) and the short-time Fourier transform (STFT) are combined. As WT produces multiresolution of frequency and time, and STFT has a fast algorithm, the combining algorithm is suitable for fast signal analysis.

Information

A New Clustering Algorithm for Categorical Attributes

Songfeng Lu, Zhengding Lu

2000, 7(4): 318-322.

中文摘要(304) PDF(8) SpringerLink

摘要:
In traditional data clustering, similarity of a cluster of objects is measured by distance between objects. Such measures are not appropriate for categorical data. A new clustering criterion to determine the similarity between points with categorical attributes is presented. Furthermore, a new clustering algorithm for categorical attributes is addressed. A single scan of the dataset yields a good clustering, and more additional passes can be used to improve the quality further.

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2000年第7卷第4期