Abstract: A technical and economic evaluation model for low-grade resources in Jiaojia Gold Mine was built up based on the breakeven theory. In different production stages, the corresponding follow-up cost was calculated, based on which the low grade resources were evaluated and classified. Differential grades were calculated to determine whether it is worthy to recovery them. The threedimensional deposit model in combination with Supac software was adopted to estimate and evaluate low-grade mineralized deposits in Jiaojia Gold Mine. Given the gold price of RMB ￥ 180 g-1, the application of differential grade can bring the mine additional 2.73 t gold metals, as well as RMB ￥ 7 500 million profits.
Abstract: Supporting drifts in Xiaoguanzhuang Iron Mine destroy badly and the deformation of surrounding rock is no convergence deformation after the drifts are excavated. According to this condition, the drift excavation process of sublevel caving without sill pillars was simulated by rock failure process analysis and the stress variation of surrounding rock was analyzed to grasp the law of ground pressure activities in consideration of rock' s creep characteristic. Simulation results indicate that the destruction form of rib spalling, floor heave and roof falling occur when the drifts are excavated. High stress concentration in the ore-rock contact zone leads to severe destruction of pillars between two drifts; with the excavation of drifts, it diverts into surrounding pillars of the newly caved. Because of excavation sequence, high stress concentration occurs in the boundary ores, which leads to difficulty in mining of boundary ores. Bolt-mesh supporting is applied to control the deformation and destruction of drifts, which can ensure mining activities safely and successfully.
Abstract: In order to solve the lack of effective management modes, a pre-warning safety management mode based on accidents discovery was put forward using the principle of safety system engineering in combination with the ideas of informationism and cybernetics. A fuzzy synthetic judgment model was established for the safety control of mine transport in view of its nonlinear, multi-factor and multi-level characteristics. Based on analysis results with the ‘4M (man, machine, medium, management) factors’ theory, some measures were provided for preventing and controlling mine transport accidents.
Abstract: The culture medium of Candida tropicalis sp. JM-1 isolated from wastewater was used as a demulsifier treating emulsion wastewater from a cold rolling plant. The emulsion wastewater was biodemulsified by 97.1% in 8 h at room temperature. The capability of the biodemulsifier was stronger than the chemical demulsifier SYM + PAC, and the biodemulsification process was less affected by the pH and temperature of wastewater. The biodemulsification capability mainly resulted from the biosurfactant produced by JM-1. The advantages of the biodemulsification are high demulsification rate, little sludge source, and without secondary pollution.
Abstract: To solve the problem of high-concentration nitrogen and phosphorus in secondary effluent, nature zeolite was modified and compounded to remove nitrogen and phosphorus by using adsorption process. Experimental results show that among these four modification methods, the modification effects can be seen as follows:salt and thermal modification 〉 salt modification 〉 thermal modification 〉 acid modification. After salt and thermal modification, the capability of ammoniacal nitrogen removal increases by 31.58%. The optimal conditions of salt and thermal modification are modifying in NaCl solution of 5.7% in mass fraction for 2 h, then 0.5 h calcination at 500℃. After compounding, the capability of phosphorus removal increases obviously. The optimal conditions of compounding are compounding in LaCI3 solution of 0.4% in mass fraction for 1 h, then 1 h calcination at 200℃. Using the modified adsorption martial to treat effluent from a secondary sedimentation tank, the problem of substandard nitrogen and phosphorus contents of effluent can be solved effectively.
Abstract: In order to study the effect of non-metallic inclusions on the mechanical properties of ultra-high strength steels for aerospace application, the micro-behavior of inclusion inducing crack initiation and propagation in two ultra-high strength steels under tensile and low cyclic fatigue loading was investigated by means of SEM in situ observations. The influence of inclusions' shape and size on crack initiation and propagation was analyzed. The results show that cracks initiate in a TiN or AIN inclusion alone under tensile loading. The larger the size of an inclusion, the more the number of cracks initiated in the inclusion is, and the lower the initiation stress of the first crack is. Cracks also initiate in a TiN inclusion alone under fatigue loading. But for a chain of AIN inclusions, cracks initiate in the matrix between two inclusions under tensile and fatigue loading. A chain of inclusions is more harmful to the fatigue properties of ultra-high strength steels than an inclusion alone, and an inclusion is more harmful to the fatigue properties than to the tensile properties.
Abstract: Corrosion of X60 steel under high-pressure H2S/CO2 coexist environment was investigated using a high-temperature and high-pressure H2S autoclave. The structure and constitution of corrosion scales were studied through scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion experiments were carried out under situations with the same H2S/CO2 partial pressure ratio (1.74) and different H2S partial pressures from 0.15 MPa to 2.0 MPa. The results show that the corrosion scales mainly consist of ferrous sulfide. The absence of ferrous carbonate in the corrosion scales suggests that the corrosion process was controlled by H2S. Under low H2S partial pressure conditions, tetragonal FeS1-x is the predominant corrosion product. When the H2S partial pressure was increased to 2.0 MPa, hexagonal FeS, hexagonal Fe1-xS and cubic FeS2 could also be observed in the corrosion scales. Localized corrosion observed on X60 steel under a higher HaS partial pressure condition can be attributed to the loose scale with S-rich corrosion products and the local breaking of corrosion scales, which also induced the decreasing of general corrosion rate at a higher H2S partial pressure level.
Abstract: The corrosion behavior and corrosion resistance of Cu-P-RE weathering steel and plain carbon steel were studied by drywet cycle immersion test. A weight-loss method was used to measure the corrosion rates of all steel samples. The results show the corrosion rate of Cu-P-RE weathering steel is much lower than that of 0.235 steel. The corrosion resistances of the weathering steels with different rare earth contents are distinguishing. The structure of rust layer on the rusty steel samples and its electrochemical reaction process were investigated by electrochemical impedance spectra techniques. An equivalent circuit was set up to represent the steel/solution interface reaction. Some electrochemical parameters such as rust layer resistance and polarization impedance were deduced from electrochemical impedance spectra of the steels. The parameters can estimate the protective properties of rust layer. There are two different diffusion processes, which are semi-infinite diffusion and finite thickness diffusion, in rust layer on the RE weathering steel. The protective properties of inner rust layer on the weathering steel can be estimated by the polarization impedance of finite thickness diffusion.
Abstract: A 45 steel/25Cr5MoA/Q235 steel clad shaft was made by hot extrusion. Its interface microstructure, chromium distribution and interfacial bonding properties were investigated by scanning electron microscope and microhardness tester. The results showed that an oxide layer with certain thickness was formed in the 25Cr5MoA/Q235 steel interface produced by thermal assembling, which would influence its interracial bonding properties, even after extrusion and hot treatment. For the 25Cr5MoA/45 steel interface produced by clearance fitting, a transition region was formed, where almost no oxide layer was found after extrusion, due to fine surface treatment before extrusion. Chromium carbide was formed in the bonding interfaces after the process of high-temperature holding, which would prevent the diffusion of carbon and chromium. The bonding strengths at the interfaces of 25Cr5MoA/Q235 steel and 25Cr5MoA/45 steel decreased after extrusion. However, compared with a clad plate, the clad layer could still not be peeled from the clad shaft easily even with low bonding strength due to the structural characteristic of the shaft. The bonding strength of the clad shaft could be enhanced after hot treatment and alloying element diffusion.
Abstract: The precipitation behavior of copper-enriched phases at different temperatures in Fe-Cu alloys and the effect of MnS inclusions on it were investigated by SEM analysis. The samples were heated to 1600℃ and kept for 20 min, some of them were waterquenched directly, and the others were furnace-cooled to a predetermined temperature and kept for 20 rain and then quenched. The results showed that in Fe-7.8% Cu alloys, copper-enriched phases precipitated both inside grains and at grain boundaries after water-quenched at 1 600℃, copper-enriched phases precipitated mostly at grain boundaries while water-quenched at 1 200℃, and there were ε-Cu phases with large size precipitates at grain boundaries after water-quenched at 1 000℃. In Fe-2.1% Cu alloys, copperenriched phases precipitated at grain boundaries after water-quenched at 1 600℃ and 1 000℃, and e-Cu phases were found inside grains after water-quenched at 800℃. MnS inclusions could be the effective nucleation substrate of copper precipitation in the alloys.
Abstract: Crack initiation and propagation in ZK60 and ZK60(0.9Y) alloy sheets during dynamic tensile process were investigated by using in situ tensile scanning electron microscope. The relationship between alloy mierostructure and rupture behavior was discussed. Experimental results show that cracks in rolling samples propagate by tearing way. There are cleavage fracture and quasicleavage fracture in the fracture zone. The loading of crack initiation in ZK60(0.9Y) alloy is larger than that of ZK60 alloy. The second phase breaks in the tensile process and the main crack propagates along the second phase. The secondary crack in matrix mostly germinates around the second phase.
Abstract: Al-12% Si and Zr(CO3)2 were selected as reactive components to synthesize Al2O3, Al3Zr particulate reinforced Al12% Si matrix composites. The as-cast samples were got via a rapid solidifying method. The relationship between thermal expansion displacement and temperature in the range of 50 to 500℃ was tested using a thermal expansion instrument and the average linear coefficient of thermal expansion (ALCTE) was also calculated. The results show that the ALCTE decreases with the increase in theoretical volume fraction of particulates (TVFP) at the same temperature. Meanwhile temperature is an important factor to influence the ALCTE. At 50 to 300℃ the ALCTE increases gradually with the increase in temperature, while at 300 to 500℃ it decreases gradually with the increase in temperature, and the value arrives maximum at 300℃. Furthermore the theoretical ALCTE values were calculated with the Rom, Turner and Kerner models individually. The test results of ALCTE are similar to the values from the Turner model. At last it is concluded by analyzing the residual thermal stress at interfaces that the (Al2O3 + Al3Zr)p/Al-12% Si composite can prevent the materials from plastic deforming at high temperature because of its low thermal expansion.
Abstract: The composition and structure of ferro-silicon nitride prepared via flashing combustion and the starting material FeSi75 were analyzed by SEM and EDS. The formation mechanism of FexSi particles in ferro-silicon nitride was studied in combination with thermodynamic analysis and flashing combustion. The results show that nitridation of metallic silicon and the silicon part of ξ phase (FeSi2.3) form silicon nitride during the synthesis of ferro-silicon nitride with FeSi75 of 74 μm. FexSi particles in ferro-silicon nitride come from nitridation of ξ phase. When the molar fraction of[Si] in ξ phase decreases to 25%, the activity of[Si] is approaching to zero and the nitridation reaction tends to balance. FexSi particles form from the residual part of ξ phase which can not be nitrided anymore. The atom proportion of Fe to Si is 3 to 1. The size of FexSi particles and homogeneity distribution relate to the particle size of phase.
Taking glass-coated FeCoSiB microwires as the research object, the influences of the concentration of hydrofluoric acid solution (HF) and reaction temperature on the removal speed of glass coatings were investigated, and the protection effects of inhibitors on FeCoSiB cores were analyzed. The results show that with the mass fraction of HF increased from 10% to 40% at 2512, the removal speed of glass coatings is increased from 0. 005 μm·s-1 to 0. 076 μm· s-1. When the temperature of 40% HF is raised from 10℃ to 45℃, the removed speed of glass coatings rises from 0. 033 μm· s-1 to 0. 234 μm· s-1. At the temperature of 20℃ to 25℃, the optimal time for removing borosilicate glass coatings of 7.59.0 μm in thickness in 40% FIF is about 150 s. Sodium thiocyanate and sodium thiocyanate plus urotropine both inhibit remarkably HF from eroding FeCoSiB cores, and the hydrogen absorption of the cores is effectively reduced by sodium thiocyanate plus urotropine, which is advantageous to maintain the mechanical properties of the cores.
Abstract: A material removal rate (MRR) model of silicon wafers was built based on friction and abrasion behaviors in wafer chemical mechanical polishing (CMP). Different slurries were designed for CMP tests of MRR. MRR results were obtained from the mechanical action of abrasives, the chemical action of slurry, and the interaction action between them. From the results it is concluded that the mechanical action produced by abrasives is the main mechanical action in wafer CMP process, and the MRR is mainly produced by the interaction between the mechanical action and the chemical action.
Abstract: A series of P(MMA-St)/P(BA-EA) acrylic latex interpenetrating polymer networks (IPNs) were prepared by employing emulsion polymerization method. Stained by a PTA (phosphotungstic acid) negative staining technique, latex particles were observed by using transmission electron microscope (TEM) to study their micro-structures and reaction processes. The results show that mass ratio of networks, swelling time and swelling style are all critical factors which influence the microstructures of latex particles greatly. The mass ratio of two networks determines the size of latex particles. Meanwhile, swelling time had dramatic effects on the thickness of the shell structure of IPNs, and swelling style affected the properties of latex films.
Abstract: T Steel/slag interfacial behavior in a stainless steel slab continuous casting mold was numerically simulated on the base of a coupled model of turbulence and multiphase fluid flow and the VOF method. The results of numerical simulation were validated by a water model. The steel/slag interracial profile and the behavior of steel and slag in the interface were obtained. By analyzing the influence of port form, port angle, SEN depth, mold width and casting speed on steel/slag interfacial behavior, it was pointed that slag entrapment was inherently influenced by steel/slag interracial behavior and the forming mechanism of interracial profiles and slag entrapment was discussed.
Abstract: The effect of rotary motion on the fluid flow and the mixing characteristics in a tundish for electromagnetic purification were studied by a physical modeling method. The visualization of flow pattern and the measurement of residence time distribution (RTD) were performed under different rotation speeds and geometric configurations. The result shows that rotational flow in the cylindrical chamber can effectively decrease the dead volume and increase the plug volume. Meanwhile, the mean residence time is prolonged thereby promoting the removal of inclusions. The flow characteristics do not become better with the rise of rotation speed, but there exists an optimum value.
Abstract: An experimental device was designed to simulate coal injection in blast furnaces. The device meets the need of coal injection with high temperature and high speed by hot air, and it can be used to simulate coal injection in a nitrogen-free blast furnace. Numerical simulation of the flow field in the device at the injection moment was performed. The results show that when the velocity of injected air reaches the maximum, the average velocity of air in the blow pipe is 162.35 m·s-1. The combustion regularity of pulverized coal was investigated using the device. The results show that the burning rate of coal increases with an increase in O/C atomic ratio. In the low O/C atomic ratio range, the burning rate of coal is comparatively low, but it increases more rapidly compared to that in the high O/C atomic ratio range. The burning rate of anthracite is lower than that of bituminous coal.
Abstract: Numerical simulation was performed to study single-phase convective heat transfer at the impinging zone of non-immersed slot jet by a finite element method (FEM). In combination with the characteristic of rolled quenching machines, some influencing factors on heat transfer such as jet velocity, nozzle-to-impinging plate spacing (height), slot width, jet direction-to-plate angle, and the temperature of water (liquid) from the slot nozzle were analyzed and designed. The results show that, for quenching plates of 100 mm in thickness, the economic process, parameters of slot jet are set as follows:jet velocity 40 to 45 m·s-1, nozzle-toimpinging plate spacing (height) about 20 mm, slot width about 2 mm, jet direction-to-plate angle about 45°, and the temperature of water (liquid) 10 to 35℃.
Abstract: In order to increase the rate of qualified products and the precision of strip width in a continuous hot strip mill, a width gauge is usually set behind the last finishing roll stand. The purpose of adjusting strip width can be attained by changing the tension of stands. Since there is a long distance from the last finishing roll stand' s central line to the width gauge, the system is usually a large time-delay and time-variation one; as a result, it is difficult to build an accurate model. An improved generalized predictive control method was proposed which has fewer requirements for modeling and can adaptively adjust the controller's parameters based on generalized estimate errors. The controller's parameters were identified directly without solving the Diophantine equation or the inverse of matrices, and the online computing time was shortened, which makes the approach be very suitable for the fast rolling process. Simulation results showed the method's validity especially for a large time delay and complex system such as width control during finishing rolling.
Abstract: For linear uncertain systems with actuator faults, the problem of robust fault-tolerant H∞ dynamic output feedback control was studied. Based on an actuator failure model with continuous gain, the sufficient condition for dynamic output feedback H∞ robust fault-tolerant controllers was proposed by using a linear matrix inequality (LMI) approach, and the corresponding design method of a dynamic output feedback H∞ controller was given. The proposed controller not only enables the system to keep robust stabilization but also achieves the given H∞ performance. A simulation experiment shows that the proposed method is effective.
Abstract: In order to help the handicapped and the elderly use computer for information interacting, a low-cost and non-contact eye gaze tracking system is designed. This system is composed of two-loop illuminators and a CCD camera. The way of getting pupil position is to do subtraction of the two images, "bright pupil" and "dark pupil", which are gained by illuminating user's eyes alternate. The pupil center is localized by ellipse fitting, and the Purkinje image can be obtained in the "dark pupil" image, then the local gazing direction can be determined. Based on the characteristic of human gazing movement, the tracking strategy of pupil that is designed by neural network and Kalman filtering is discussed. At last, an eye gaze mapping model and its calibration are given.
Abstract: To meet characteristics of collaboration service's structural relationship, a collaborative service model was studied, which is divided into internal and external service models. This method can well protect collaboration service insider information. Severn equivalent simplification theorems of typical collaboration e-commerce service modes based on Stochastic Petri-net and their verification are provided. This method was applied to e-commerce order process analysis, and numerical results show effective.
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
