Abstract: A mathematical model was built up to realize a quick reserve evaluation of polymetallic deposits based on a multidimensional probability distribution function in view of that there exists a certain correlation between valuable components in the polymetallie deposits. The model was verified by studying a gold-copper deposit ease. In the case, it was proved that the probability density of both Au and Cu grades obeys a logarithmic normal distribution, based on which the correlation between them was verified. Then a function of the muhidimensional probability distribution of grades in the gold-copper deposit was established after the probability density distribution was expanded from one-dimension to muhi-dimension. The corresponding reserves for different cut-off grades were calculated with the help of the function. The model was proved reliable for the calculation error was less than 10%, which is an accepted accuracy for reserve evaluations.
Abstract: The long-wall method was used to mine a kind of gently inclined and extremely thin iron ore deposit. A similar material model was built for the iron ore deposit, the deformation, stress and failure of cap rock were monitored with an electronic total station, strain gauges and digital cameras. The collapse law, the variation of stress and displacement, and the deformation mechanism of stiff cap rock were studied during mining the gently inclined and extremely thin iron ore mine by long-wall method. Experimental results show that the collapse of cap rock is sharply intermittent and jumping, the fracture pace of the collapse roof is the same as previous steps, and the orientation of fracture is almost parallel. In the vertical orientation, the fracture pace relates with the location of rock. The fracture period and the movement law of cap rock were also obtained.
Abstract: Iron and nickel minerals in a nickel laterite ore were deeply reduced to metallic iron and nickel, and then they were magnetic-separated for the enrichment of an iron-nickel concentrate. The reductive roasting parameters were optimized and the optimal conditions are obtained as the C/O atomic ratio of 1.3, the reduction time of 80 min, the CaO content of 10%, and the reduction temperature of 1 300℃. Under these optimal conditions, the grades of nickel and total iron in the iron-nickel concentrate are 5. 17% and 65.38%, and the recovery rates of nickel and iron are 89.29% and 91.06%, respectively. The deeply reduced ore and the magnetic separated concentrate were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive Xray spectrometer (EDS). The results show that metal particles of ferro-nickel are found in the reduced ore. Nickel is dissolved in ferronickel, and a little portion of iron exists as FeO. A large amount of gangue is removed by magnetic separation, and the concentrate contains iron, ferro-nickel, FeO, and little CaO·MgO·2SiO2.
Abstract: In order to study the reaction rate of RH vacuum decarburization and its influencing factors, and effectively control the change in carbon content of ultra-low carbon steel in the RH vacuum treatment process, a mathematical model of RH vacuum decarbnrization was established on the basis of the kinetic and thermodynamic theories. A relationship between the reaction depth of internal decarburization and the decarburization reaction rate was studied by the RH vacuum decarburization model. The calculated results of this model show that the change in reaction depth is corresponding to the decarbnrization reaction rate. Taking a pre-vacuum operation can increase the reaction depth, decrease the impact of the early decarbonization turning point and accelerate the decarburization reaction in the early stage. The critical point of time from internal to surface decarbonization is found out in the late of RH treatment.
Abstract: Equilibria between 60Si2MnA molten spring steel and such low melting point inclusions as MnO-SiO2-Al2O3 inclusions, CaO-Al2O3-SiO2 inclusions and CaO-Al2O3-SiO2-15% MgO inclusions were thermodynamically studied by the thermodynamic software FactSage at three different temperatures of 1 873, 1 823 and 1 773 K. On the basis of these calculations, the compositions of the liquid steel were determined when these low melting point inclusions formed at the different temperatures. Simultaneously, it was also discovered by comparison that low temperature is more beneficial to fulfill the control of the low melting point inclusions under the condition of low soluble oxygen content. The soluble aluminum content for the formation of CaO-Al2O3-SiO2-15% MgO inclusions is much higher than that for the formation of CaO-Al2O3-SiO2 inclusions, and it is easily controlled in actual production.
Abstract: The temperature, stress and flow distribution of a bloom in GCr15 steel were simulated based on a mixed Lagrangian-Eulerian method, and the simulated results are consistent with practical blooms. The corner temperature of the bloom shell is higher than the middle parts. The tendency of the bloom surface temperature from top to bottom decreases gradually. Moreover, the isothermal zones are similar to the change of flow fields. The middle thickness of the casting bloom shell is about 17.5 mm, and the corner thickness is about 13.2 mm. The stress in the solidification shell is mainly thermal stress. When the shell is just out of the mold, the outer surface is in a compression state, while the front of solidification is in a completely tensile state. The effective strain increases from the outer surface to the front step by step. The liquid steel expands and its velocity decreases gradually in the progress. When the flow arrives to a certain depth, there are two symmetric upward backflows and a backflow area is formed by the side of face solidification downward and the centre upward.
Abstract: The effect of cooling conditions on the corner transverse cracks of slabs with different section dimensions was studied by nozzle performance measurements, remehing and solidification cooling experiments and numerical simulations. The results show that the corner temperature is lower than the A3 temperature earlier for slabs with section dimensions of 1000, 1160 and 1250 mm during a stronger cooling. There is a large number of film-like proeutectoid ferrite along grain boundaries, and transverse cracks form along prior austenite grain boundaries when straightening. To prevent from these transverse cracks, a process to control the surfaee mierostrueture of a slab was adopted and applied to actual production at Pansteel.
Abstract: Precipitates in low-carbon low-silicon non-oriented electrical steel containing Cu were studied and the precipitation mechanism was analyzed by means of energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED). It is found that the equiaxed precipitates of Cu with B2-1ike structure distribute dispersively in the non-oriented electrical steel. The precipitation mechanism involves general precipitation, dislocation precipitation, interphase precipitations formed by the ledge mechanism and the bowing-out mechanism. General precipitation can occur at the three aging temperatures of 550, 650 and 750℃. Dislocation precipitation takes place only at low aging temperature (550℃), with a special form of parallel short rows. Interphase precipitation formed by the ledge mechanism is in a form of straight rows which can separate out at the above three aging temperatures, but the most appropriate temperature for precipitation is 650℃. Interphase precipitation formed by the bowing-out mechanism can occur only at high aging temperature (750℃), with a form of curve rows.
Abstract: A new production route for producing a new class of oxides dispersion strengthened (ODS) steels was investigated. The steel produced by the chemical socking method has high temperature strength, low ductile-to-brittle transition temperature, good creep properties and void swelling resistance. The formation process and behavior of oxides (Y2O3) in the prealloyed powders were analyzed in the process of thermal decomposition, interracial reactions of hot isostatic pressing, and precipitation of deformation processing. A uniform distribution of oxide particles could be obtained by selecting reasonable parameters.
Abstract: An Fe-Ni alloy coating on 20 steel was prepared by electrodeposition technology. The effects of Fe2+ concentration in the bath on the deposition rate, chemical composition, phase structure, micro-hardness and corrosion resistance of the coating were investigated, and the corrosion mechanism was analyzed. Experimental results show that the Fe-Ni alloy coating is nano-crystaIline, and the iron content in the coating increases with increasing Fe2+ concentration in the bath. The change in micro-hardness of the Fe-Ni coating is related to the ordered solid solution degree of Fe atoms in the Ni lattice. The corrosion resistance of the Fe-Ni alloy coating is superior to 20 steel, and it is the best when the Fe2+ concentration is 0.01 mol· L-1. With the increase of iron content in the coating, the content of Fe-Ni alloy phase, which has passivation properties and high nickel ratio, and the corrosion resistance decrease. But the nanostructure of Fe-Ni alloy phase is significant refined, and it accelerates the passivity, and thus the corrosion resistance is improved. Due to the contradiction the relationship between corrosion resistance and coating iron content is not obvious. High porosity is one of the reasons for the low corrosion resistance of the Ni-Fe alloy coating.
Abstract: Porous ceramics were prepared from fly ash by adding a pore-making agent. Some effects of the amount of the poremaking agent and sintering temperature on the properties of the porous ceramics were studied. The properties of specimens were characterized by pressure mercury analyzer, X-ray diffraction (XRD), and field emission scanning electron microscopy (SEM). The results show that with the pore-making agent increasing, the porosity and water absorption increase, but the bending strength and density decrease. Increasing the sintering temperature can improve the bending strength of the porous ceramics. However, main phases in the porous ceramics are similar at different sintering temperatures. As the sintering temperature is more than 1175℃, the porosity and gas permeability decrease significantly. When the amount of the pore-making agent is 35% and the sintering temperature is 1175℃, the fly ash porous ceramics for filtration have high bending strength, advanced porosity and high specific surface area.
Abstract: Consulting a practical dephosphorization slag in the converter, samples with different levels of F, P2O5, FeO, MgO and basicity were prepared in laboratory, and the effect of composition on their solubility in citric acid was analyzed by chemical analysis methods. The results show that when the slag contains fluorine, P and F mainly form fluorapatite, and the solubility in citric acid of the slag sharply decreases when the fluorine content increases in the slag. if there is no any fluorine in the slag, the solubility in citric acid can be reached up to 92.5%, but when the mass fraction of fluorine in the slag reaches to 0.5%, the solubility in citric acid drops to less than 50%. The solubility in citric acid is improved with the increase of basicity, for increasing Ca2+ can destroy the Si-O network structure. With the increase of MgO content, the solubility in citric acid increases since in the process of cooling, Mg2+ inhibits the precipitation of β-Ca3(PO4)2 crystals in which P can not be dissolved easily in the 2% citric acid. The solubility in citric acid decreases with the increase of P2O5 content, for P5+ is formed as PO43- complex ions with O2-, P5+ locates in intensive gaps formed by O2-, and the complex ions can not dissolved easily in the 2% citric acid. The solubility in citric acid will be decreased with the increase of FeOn.
Abstract: The electroplating sludge was treated for the comprehensive recovery of copper, chromium and nickel with procedures including sulfuric acid leaching, copper precipitation, chromium removal by two-stage neutralization, and nickel carbonate concentrating. Various processing factors were studied and the optimum conditions were obtained as follows:0.5 h, 50℃, and 0. 8 times of stoichiometric sulfuric acid addition for sulfuric acid leaching; 1 h, 85℃, and 1.2 times of stoichiometric copper precipitator addition for copper precipitation; the two-stage chromium removal method decreases nickel loss in the precipitation process. More than 98% of copper, 99% of chromium and 94% of nickel originally contained in the sludge were successfully recovered by using this process.
Abstract: An oxygen blast furnace was divided into the three zones of hot zone, solid charging zone and gas heating zone. Physical constraints and chemical constraints of each zone were analyzed in detail. Based on material balances and energy balances, a multizone constrained mathematical model was established for oxygen blast furnaces. Theoretical analysis and calculation results show that the multi-zone constrained mathematical model can make up for deficiencies in the whole furnace heat balance and reflect the heat value in use of different zones. The solid charging zone is constrained by indirect reduction and heat balances. With the increase of metallization rate, the need of cycle gas is increased in the solid charging zone. When the metallization rate is very high, the hot zone and solid charging zone meet the thermal equilibrium conditions; although the calculated fuel ratio is low, the gas volume in the gas heating zone can not achieve balance.
Abstract: Based on carefully analyzing the heat transfer mechanism of the cooling process of high temperature sinter, a one-dimensional unsteady mathematical model was established for the gas-solid heat transfer process of high temperature sinter according to energy conservation. The mathematical model was verified to be correct and reliable by real data. Lastly, the model was used to investigate the effects of main operation parameters such as the velocity of cooling air and the moving speed of the trolley on the cooling process of the annular cooler, and some proposals were put forward for operations of the annular cooler.
Abstract: Topology optimization based on a homogenization method was applied to the articulated body of an articulated dump truck under multiple loading cases. The uncertainty of weights and the reliability of experts were taken into consideration when the weights were determined under multiple loading cases. An uncertain quantified expression of the experts' advices was set up by means of the blind number theory, and the weights under every loading case were got and applied to topology optimization under multiple loading cases. Finally, the reliability of the articulated body was analyzed. The rationality of the way to get the weights based on the blind number theory was also proved.
Abstract: A compression method of electrical signals from rolling mills based on adaptive morphological wavelets was proposed, aiming at the problem of data compression to nonlinear and non-stationary signals. In combination with the morphological characters of electrical signals, the median operator as an updating operator of morphological wavelets was chosen to decompose the signals, so the updating operator for morphological wavelet decomposition is adaptive with the partial morphological characters of the signals. Experimental results of signal compression to electrical signals from rolling mills in industrial environments show that the signals with high compression ratio are acquired and the morphological characters are reserved after processing by the morphological wavelet method. Because of simple calculations, the proposed compression method of electrical signals can be available for online real time monitoring systems.
Abstract: A state-space model of the control system in hot continuous rolling was proposed by using a recursive least squares algorithm by linearizing and discretizing the rolling force and thickness control equations. After an optimal information fusion algorithm based on Kalman filtering was presented, an asynchronous information fusion estimation algorithm was built for the complex multi-variable system of hot continuous rolling. This model was applied into the prediction of strip thickness and plasticity coefficient Q in the hot continuous rolling process. At last, the real-time forecast results of the coming strip thickness and plasticity coefficient of strips were synthetically utilized in the thickness control system of hot continuous rolling to improve the quality of final coming strip thickness.
Abstract: Designing a preview controller for discrete-time muhirate input systems was considered. At first, by making use of the lifting technique to eliminate the muhirate characteristic and the state time-delay of the sampled system, the problem was converted into a controller design problem for a single-rate no-delay sampled system. Because of the existence of state time-delay, the historical values of input data would be introduced during the lifting process. However, the historical values and the state delay were put into the state vector of the expanding system so that no error was introduced during the lifting process. For the lifted system, the problem was changed into an adjust problem via the standard method of dealing the optimal preview control and by constructing an expanded-error system, and finally an optimal controller with preview compensation was derived subsequently. Through transformation a preview controller was then obtained for the original system. The existence condition of the preview controller was discussed. Numerical simulations proved the effectiveness of the preview controller designed in the paper.
Abstract: For solving the slab location decision problem with hybrid stowage, a slab location model using a membership function was built to express the level of matching on the related attributes of length, width and thickness between the storing slabs and stored slabs in a warehouse. According to the characteristics of the problem, a hybrid discrete particle swarm algorithm, called DPSO-MC, was proposed based on crossover and mutation in genetic algorithms. Experimental results on a real case of a steel plant demonstrate that the model and algorithm are feasible and effective.
Abstract: A numerical analysis model of slope dynamic response was established with FLAC program to study slope response rules at different dynamical loads and different rock parameters. The results show that the dynamic response magnification coefficient of a slope under dynamical load is not proportional to the dynamical load frequency. There exists a dominant frequency at which the dynamic response magnification coefficient is larger than those at other frequencies. According to the simulation results, the dominant frequency is dependent on the shear modulus and density of the rock mass. A functional relation of the dynamical response magnification coefficient with dynamical load and rock mechanics parameters was put forward.
Abstract: Based on the potential flow theory, the influence of water on the natural vibration characteristics of a typical rectangular entity pier as the prototype was analyzed at different water depths. As the same time, the distribution of hydrodynamic pressure acting on the pier, the action spot of hydrodynamic force and the effect of water on the seismic response of the pier were analyzed under the condition of different water depths and types of seismic loads. The results show the natural vibration period, the peak values of bending moment and shear force at the bottom of the pier increase with the rise of water depth. The bending moment and shear force increase by 31% and 50% at most respectively, which indicate that the effect of water on the dynamic response of the pier should not be ignored. The influence of different seismic waves on the distribution of hydrodynamic pressure acting on the pier is not identical. The results of hydrodynamic force acting on the pier according to the Japanese specification are closer to data in this paper.
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
