Abstract: Gas distribution and flowing in Qinan Mine were calculated and analyzed by means of the Navier-Stocks formula based on the Darcy law and then the method of CFD numerical simulation was used to visually display the result.The gas collection course in the falling porous media at the upper corner of goaf was simulated theoretically, which clearly illustrated the gas movement and flow pattern in goaf when the gas was drained.Based on the simulation result, the gas was drained through high-position boreholes placed in the fracture area in Qinan Mine, and it was proved to prevent the gas from flowing to the upper corner.As a result, piping measurements show, the gas concentration in the drainage pipeline reached to about 30% to 80% and the gas concentration of return air was lowered to as low as 0.3%.
Abstract: The fusion-flow processes of seven various types of imported iron ore fines were studied with visual high-temperature equipment.The evaluation indices T30, T55, TR and SR, which represent fusion characteristics, were determined on the fusing curve.Then, the fusion characteristics of various iron ore fines in sintering were observed according to the indices.The results show that limonite from Australia is prone to generate liquid phase, but it is marked with bad properties known as a thinner temperature-range, inferior temperature-operation and a lower safety.Semi-limonite ores from Australia are slightly better than the limonite in temperature-operation, but the effective liquid phase amount of the semi-limonite is sufficient under low-temperature sintering conditions.The fusion characteristics of hematite from Australia, South Africa and southern Brazil are relatively appropriate, and the former one is easier to generate liquid phase while the last two have better temperature-operation and safety.It is revealed that concentrates from south Brazil and hematite from northern Brazil are difficult to generate liquid phase.The ore matching optimization principles based on fusion characteristics were proposed by studying on the fusion characteristics of various iron ore fines.
Abstract: High-basicity coal-bearing iron oxide briquettes with a CaO/SiO2 of 2.0 and a C/O molar ratio of 1.1 to 1.2, which were produced by BOF steelmaking sludge, BF dedusting ash and pyrite cinder, were self-reduced at temperatures from 1 330 ℃ to 1 380 ℃ to study the phenomena of desulfurization and dephosphorization.During the self-reduction, the desulfurization ratio by evaporating as COS is 20% to 40%.Residual sulphur is attached in slag and it can be separated from iron nuggets.The total desulfurization ratio is more than 97%.Excessive CaO in high-basicity coal-bearing iron oxide briquettes can restrain the reaction of phosphorous pentoxide reduced by carbon.The reduced phosphorous is partially absorbed by nascent metallic iron, and the other escapes from the briquettes.Phosphorous pentoxide attached in gangue which is not yet reduced can be separated from iron nuggets.The total dephosphorization ratio can reach up to 50% to 60%.It is indicated that clean iron nuggets with low sulphur and low phosphorous can be produced by self-reduction of high-basicity coal-bearing iron oxide briquettes
Abstract: A mathematical model of decarburization in EAF steelmaking was constructed to predict the variation of carbon content in the bath continuously and control the terminal point of carbon content on the basis of the technology of fume composition infrared detecting, calculations of mass balance and production data such as carbon amount and oxygen flow.The simulated results of production data form the 50 t UHP EAF in Special Steel Plant of Laiwu Iron and Steel Co.Ltd.indicate that this model achieves its aim to continuously predict and terminally control carbon content in the molten bath.It is also shown that the decarburization rate which can achieve 0.12% to 0.16% min-1 is mainly influenced by oxygen flow rate.This model can be used for oxygen supply optimization to reduce oxygen consumption.
Abstract: Considering that the viscosity of molten slag cannot be accurately calculated from(NBO/T) ratio using the traditional method, this paper firstly studied the effects of different oxides on the polymerization degree of molten slag, proposed a new method for calculating(NBO/T) ratio, and developed an estimation model of viscosity for aluminosilicate melts based on(NBO/T) ratio.The new viscosity model was adopted to predict the viscosities of the ternary system of CaO-SiO2-Al2O3 and the quaternary systems of CaO-SiO2-MgO-Al2O3 and CaO-SiO2-Al2O3-RO(R2O), and the calculated results were satisfactory in comparison with those of the Urbain model and the modified Iida model.The present model can predict the viscosity of the CaO-SiO2-MgO-Al2O3-R2O(K2O or Na2O) system effective.
Abstract: With cold-rolled strips(SPCD) under Baotou CSP line as experimental materials, two batch annealing processes, double-step annealing and single-step annealing, were applied by laboratory experiments.The characters of textures, microstructures and properties were studied under different annealing processes.The results indicate that the double-step annealing process enhances the intensity of γ-fiber and the {111}〈110〉 of α-fiber, but the value of Δr increases, too.The difference of pre-recovery between the two annealing processes delays nucleation in the unfavorable regions, consequently leading to the difference of favorable textures.Upon the double-step annealing process, the high intensity of {110}〈110〉 results in the higher value of Δr.
Abstract: The effects of quenching-tempering heat treatment processes on the microstructure and properties of X80 pipe fittings steel were studied by scanning electron microscopy(SEM), electron backscatter diffraction(EBSD), transmission electron microscopy(TEM) and other experimental methods.The results show that after the first quenching at 930 ℃, the yield strength first increases and then declines with the tempering temperature increasing, reaching the maximum 588 MPa at 630 ℃, but the tensile strength decreases gradually and reaches the lowest 630 MPa at 680 ℃.After the second two-phase quenching and the tempering at 630 ℃, X80 pipe fittings steel has the optimum comprehensive mechanical properties, while its impact strength significantly reaches 210 J at -50 ℃.This can be attributed to the fine-grain austenite microstructure after the secondary quenching at 860 ℃, the combined effect of recovery and softening of the dislocation sub-structure, the blunting mechanism along strip boundaries, and the precipitation strengthening from decomposition of massive M-A after tempering at 630 ℃.
Abstract: The influence of boron on the texture of low carbon deep drawing steel sheets was studied with B-contained and B-free low-carbon hot-rolled and batch-annealed strips produced by CSP(compact strip production) as experimental materials.Texture formation and development of the hot-rolled and batch-annealed strips were analyzed in terms of chemical composition and precipitates by electrolytic chemical phase analysis, internal friction and Raman analysis.The results show that the AlN content of B-free hot-rolled strips is much more than that of B-contained hot-rolled strips, but the latter texture is better than the former.The AlN contents of B-free and B-contained annealed strips are almost equal, however, the texture of B-contained annealed strips is bad.It is indicated that AlN is not only the determinant factor that affects texture development, but B and BN also have some influences.
Abstract: The effect of niobium on the phase transformation law of Si-Mn spring steel was studied by thermal simulation experiment, and the deformation-induced precipitation behavior of NbC was analyzed.The results show that pearlite transformation is delayed;and the minimum cooling rate of martensite transformation is reduced from 5 ℃·s-1 to 3 ℃·s-1.The pearlite lamellar spacing is refined, and the cementite lamellae become thinner, irregular, bending and discrete.Deformation-induced precipitation NbC locates in the ferrite lamellae, pearlite pellet borders and dislocations when the Nb-bearing spring steel was deformed at 850 ℃, and NbC is approximately spherical shape with a diameter of 10 to 15 nm.
Abstract: The effects of pH values on the stress corrosion cracking(SCC) of 304L stainless steel in high-temperature and high-pressure water were studied using slow strain rate tension(SSRT) tests.The fracture morphology of SCC specimens was analyzed with the aid of scanning electron microscopy(SEM).It is shown that 304L stainless steel exhibits a high susceptibility to SCC in weak alkaline and acidic solutions at 300 ℃, and the susceptibility increases by decreasing the pH value of the solution.In neutral solutions, both the strength and toughness of 304L stainless steel display a limited loss, indicating that 304L stainless steel has a low susceptibility to SCC.Fractography analysis is also consistent with these conclusions.
Abstract: AlCN amorphous thin films with different Al contents were deposited on Si(100) substrates by magnetron sputtering, followed by vacuum annealing at 700 ℃ and 1 000 ℃ respectively.The microstructures of the as-deposited and annealed films were characterized by X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM), and the values of nanohardness and elastic modulus were measured by the nano-indention method.The results indicated that the organization and microstructure of the annealed AlCN films strongly depended on Al content.For the thin films with low Al content, delamination rather than crystallization occurred after annealing at 1 000 ℃, but for the thin films with high Al content, annealing accelerated the formation of AlN nanocrystallites, which were embedded into amorphous matrices.The density and size of the nanocrystallites were both found decreasing with increasing depth from the film surface.With the increasing of annealing temperature, both the values of nanohardness and elastic modulus decreased;but for the AlCN films with high Al content the decreasing trends slowed down due to the formation of nanocomposite structure.
Abstract: Porous SnO2-Cu2O composite films were prepared through thermal oxidation of porous Sn-Cu alloy electrodeposits in air.The effects of the Sn2+/Cu2+ molar ratio of solutions on the morphologies, constituents and structures of coupled SnO2-Cu2O porous films were investigated by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS) and X-ray diffraction(XRD) analysis.And the photocatalytic activity of the films was tested by photodegradation of rhodamine B under irradiation of a low-pressure mercury lamp.The results indicate that a coupled SnO2-Cu2O porous film with a Sn∶Cu ratio of 3∶1 has the best photocatalytic activity for degradation of rhodamine B.The film was prepared by electrodepositing a Sn-Cu alloy in a solution containing 0.01 mol·L-1 CuSO4, 0.05 mol·L-1 SnSO4, 1.5 mol·L-1 H2SO4, 7 mL·L-1 formaldehyde and 0.001% polyethyleneglycol octyl phenyl ether(OP) at 6.0 A·cm-2 and 20 ℃, then heating the Sn-Cu alloy at 200 ℃ for 2 h followed by 400 ℃ for 2 h in air.The reason for a higher photocatalytic activity of the film may be its three-dimensional porous morphology and proper Sn/Cu ratio.
Abstract: Nanopowders synthesized by a co-precipitation method were modified by spray drying and spherical particles were prepared for transparent ceramics of yttrium aluminum garnet.The phases of the powders were analyzed by X-ray diffraction(XRD);the shape, size and agglomeration of the powders before modification were studied by transmission electron microscopy(TEM);the shape, size and dispersion of the powders before and after modification were characterized and the surface morphology of polished ceramics after hot corrosion was also observed by scanning electron microscopy(SEM).The results show that the PVB addition of 1.0% is the best;the density of molding samples by the modified powders increases significantly, thus influencing the density of the ceramic and the morphology of grain boundaries;using the vacuum sintering technology, the density of the ceramic is up to 99.95%, the average grain size is about 10 μm, the size distribution is more uniform, the grains and boundaries are clean, the impurities and porosity do not exist.
Abstract: 5Cu-9.5NiO-85.5NiFe2O4 cermet anodes were tested in different low-temperature electrolytes for aluminum electrolysis.Post-electrolysis microscopic examination of the anodes was carried out by scanning electron microscopy(SEM) and X-ray diffraction(XRD).The contents of impurities both in the bath and aluminum were measured by inductively coupled plasma atomic emission spectrometry(ICP-AES).The corrosion rates of the anodes in different electrolytes were calculated and compared.The results indicate that when the addition amount of K3AlF6 is around 20% in Na3AlF6-30AlF3-based electrolytes, the anodes show good anti-corrosion properties.
Abstract: Based on the principle or laws of energy conservation, fluid flow, and heat and mass transfer, a mathematical model of pellet cooling and oxidation was established and solved by a three-diagonal matrix algorithm.Its numerical simulation software was developed with Visual Basic 6.0.A field test was performed and the established model was verified by practical measured results.The maximum relative error between computational and measuring results is 4.8%, indicating that the developed model is correct and reliable.A numerical simulation of the pellet thermal process in an annular cooler was conducted with the developed computational software and the temperature distribution of the pellet bed was gained.The simulation results show that the main influencing factors on the cooling process of the pellet bed in an annular cooler are air velocity in the first cooling zone, pellet bed thickness, pellet size and the annular cooler’s velocity.Under the research condition, the reasonable operation parameters are the following:the range of pellet bed thickness is from 550 to 800 mm, the range of pellet size is from 7 to 16 mm, the range of air velocity in the first cooling zone is from 1.2 to 2.5 m·s-1, and the range of the annular cooler’s velocity is from 1.0 to 1.5 m·min-1.
Abstract: A mathematical model was developed for a 60 t·h-1 alumina clinker rotary kiln on the comprehensive consideration of the effects of heat transfer and mass transport processes.The model was utilized to study the impact of the moisture content of feeding slurry on the thermal process in the rotary kiln, and to analyze the clinker sintering method by the substitution of dry clinker sintering for wet-sintering so as to increase production and reduce consumption.The results show that when the moisture content of feeding slurry reduces to 20%, the production capacity of the rotary kiln improves by 24% compared with the actual working conditions, correspondingly the coal-fired unit consumption declines up to 18%;with the water content of feeding slurry further decreasing, the variation tendency of production capacity and coal-fired unit consumption slows down.
Abstract: Structure characteristics of a combined compliant structure formed with a flexible hinge and a flexible beam are studied.The thickness ratio and the length ratio between the flexible hinge and the flexible beam are two characteristic parameters which influence deflection characteristics of the combined compliant structure.A group of combined compliant structures with different thickness ratios and length ratios are given, and their deflection is analyzed with the finite element method and the pseudo-body model, respectively.The influence of thickness ratio and length ratio on their deflection is discussed.Based on different values of the two characteristic parameters, the combined compliant structures are classified into different kinds.
Abstract: A grey predicted linear programming model was applied to the optimal allocation of production capacity of polymetallic mines.After predicting each positioning coefficient by the grey prediction model, the grey linear programming problem was turned into a general linear programming problem.The results show that the GM(1, 1) model error checking of positioning coefficients is passed.A polymetallic mine after optimizing the allocation of production capacity can achieve a reasonable allocation of productive materials and profit maximization
Abstract: Based on the precise design theory of steel manufacturing processes, a two-step design method using Gantt chart combination was proposed.Firstly, the initial steel production process was established by the traditional design method according to the product mix.Secondly, the combination modes of Gantt chart equations were established based on the reasonable Gantt chart combination modes and the yield proportion of each steel grade in the product mix.The equations were solved by the successive over-relaxation iteration method to calculate the process productivity.The result shows that the process productivity is less than the productivity of equipment in the traditional design method.By the productivity calculation method based on Gantt chart combination, the influence law of the nominal capacity of decarbonization converters and casting speed on the process productivity and the operation rate of equipment was analyzed, and the rational process productivity and casting speed were proposed according to different nominal capacities of decarbonization converters.
Abstract: A mathematical model of CO2 emissions in iron and steel enterprises was established, and based on production data from a domestic steel plant, the amount of annual CO2 emissions of the steel plant was calculated by using this model.The influences of the used energy types and the produced steel types on CO2 emissions were discussed.Scenario analysis was conducted to analyze the effects of different ways and strategies on the reduction of CO2 emissions, with four scenarios assumed:using natural gas instead of all the steam coal, using EAF processes to replace integrated steelmaking, considering feasible lowest process energy consumption(FLPEC) and applying waste heat recovery technology.The result shows that the using of waste heat recovery technology has little effect on CO2 emissions, and only 3.39% of CO2 emissions would be reduced;however, using EAF processes to replace integrated steelmaking has the most effective impact on the reduction of CO2 emissions, it would reduce 45.07%, and even if indirect CO2 emission, which is caused by EAF electricity consumption, is counted, the reduction of CO2 emissions would still reach 24.30%
Abstract: Based on an arithmetic progression with an input secret key, a method is proposed to construct n-dimensional generalized Arnold transformation matrixes.Direct calculation algorithms are also presented for the transformation matrix and the inverse transformation matrix.The algorithms are only relevant to the secret key and their time complexity is equal to n(n+1)/2 times multiplication operation.Using the n-dimensional generalized Arnold transformation matrix as a transform matrix, and adopting double product-like scrambling in the image position space and the hue space, the image scrambling method has long period and is public, and can prevent many attacks and thus greatly enhances the system’s security.Moreover, when the inverse transformation matrix is applied to restore the scrambled image, the period of the transformation matrix is not needed to calculate.Simulation experiments show that the proposed method is effective and very secure
Abstract: As an effective nonlinear dimensionality reduction tool, the local tangent space alignment algorithm (LTSA) can obtain the global low-dimensional embedded coordinates of sampled data from a high-dimensional space. Introduced into multi-pose ear image recognition, LTSA has to improve to solve its problems in image recognition. An adaptive neighborhood selection strategy is proposed and a novel multi-pose ear recognition method based on this improved LTSA is present. Experimental results illustrate that it is an effective multi-pose image recognition method which can obtain better recognition rates than the traditional linear ones when the pose varies a lot
Abstract: An induced electromagnetic measuring system of steel bar stress was set up and the electromotive force of the steel bar surface was measured under the condition of tension to find a new way of stress testing. The stress-electrical spectrum lines were obtained by changing measurement frequency, the data were processed and the stress distinguishing was formulated by the method of least squares. The measuring mechanism of stress-electromotive force was analyzed. According to the experimental results, while the tensile stress rising, the change of induced electromotive force shows two kinds of variation characteristics, increasing at the first and then decreasing at the high stress level, or increasing continuously, at a fixed frequency value between 100Hz and 600Hz. The induced electromotive force reduces generally with increasing frequency at a fixed stress value. The stress-electromotive force spectrum lines of steel bars rise with the increment of stress levels.
Abstract: The simulated earthquake experimental study on a large desulfurization tower was carried out using shaking table test. A 1:15 reduced-scale thin-walled steel structure model of the desulfurization tower was designed for testing and the dynamic responses of the model were discussed. The responses of peak acceleration were studied under a sine wave, Tianjin wave and Hyuga seismic wave in various angles and the most unfavorable input angle was analyzed. The results show that the influence of the input angle of an excitation wave can not be ignored, the maximum influence is in the direction of 30° and the minimum is in the direction of 60°. The complexity of the thin-wall desulfurization tower can affect the dynamic characteristics of the structure to a great extent. The weight of the tower top is one of the main factors causing the distribution of peak acceleration uneven in tower height.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
