Abstract: Based on predicted methods of demand for iron ores,eight basic factors influencing the demand for iron ores in China were selected for single factor regressing analysis.The results show that the degree of correlation between the eight basic factors and demand for iron ores is more than 0.9.The principal component analysis method was used to analyze the relationships among the eight basic factors and four principal components were determined among the eight basic factors.Combined the principal component analysis method with the regressing analysis method,a prediction model of demand for iron ores was established.Using the model,the demands for iron ores in 2015 and 2020 in China were predicted and their values are 29.76 billion tons and 26.68 billion tons,respectively.
Abstract: In order to solve the creep control problem of surrounding rock for the crushing chamber in Jinchuan Mine No.3,the deformation of channel surrounding rock in the crushing engineering system was monitored and it showed obviously rheological properties which include rapid deformation,slow deformation and deformation stabilization.By analyzing the effect of the stress environment of surrounding rock,mineral composition and ground water on the deformation of surrounding rock,a suitable high-stress and tectonic belt rheological model was proposed and its rheological parameters were analyzed.The rheological process of Jinchuan rock is a complex process in which elastic,plastic,visco-elastic and visco-plastic deformations coexists,with a highly nonlinear characteristic.The optimum time of the second support was analyzed in theory.The second support as the best opportunity ought to be carried out within the third week after deep rock excavation and the first support in the Jinchuan Mine No.3,and the allowable deformation should be controlled between 5 mm and 150 mm.
Abstract: Grade Ⅰ and grade Ⅱ fly ashes were chosen to produce a cementitious material to replace traditional cement using lime and flue gas desulphurization gypsum(FGD) as stimulation agents.Whole-tailings backfilling samples were prepared with the ratio of the cementitious material to whole-tailings being 1:4 and the ratio of water to the cementitious material being 1:1.The compressive strengths of the whole-tailings backfilling samples cured under the conditions of 45±1℃ for 3d and 20±1℃ for 28d are 5.432 MPa and 3 to 7 MPa,respectively.This generally satisfies the requirement of cemented backfilling for underground mining.Besides,relationship curves between the mass fraction of slurries and the slump were obtained and the mass fraction of the pumpable paste backfilling with the cementitious material is from 80.5% to 83.0%.By the analyses of X-ray diffraction and scanning electron microscopy,hydration products of the cementitious material are mainly gel,ettringite and calcite.
Abstract: With a nickel laterite of 1.86% Ni and 13.24% Fe as a sample,the influence of different types of coal on selective nickel reduction in nickel laterite reduction roasting was studied with stone coal or anthracite as a reductant.It is indicated that nickel can be selectively reduced with stone coal as a reductant.The results obtained by X-ray diffraction(XRD) and scanning electron microscopy(SEM) show that taenite is the main form of nickel and iron in the roasted products when the dosage of coal is small,but the main mineral form changes into kamacite with the dosage of coal increasing.At the same time,with the dosage of coal increasing,the proportion of nickel decreases and the proportion of iron increases in Ni-Fe containing minerals produced after roasting.The roasted products are formed as taenite with stone coal as a reductant,the amount of gained Fe is lower but the selectivity for nickel is stronger than that with anthracite as a reductant,so Ni-Fe concentrate ores with high grade of nickel are obtained.
Abstract: In the desulfurization process of sintering flue gas by dual alkali,the oxidation of desulfurization by-products,calcium sulfite,is an important chemical process.Laboratory experiments were designed for simulating the oxidation process of calcium sulfite.The influencing factors and change law of the oxidation efficiency of calcium sulfite were investigated by changing the reaction time,temperature,initial pH values,stir intensity,air flow and solid content.It was also studied whether manganese ions as a catalyst have effect on the oxidation.The results show that the oxidation of calcium sulfite is dependent on the reaction time,temperature,initial pH values,stir intensity,air flow and solid content,and manganese ions can obviously promote the oxidation of calcium sulfite.The most suitable process conditions were determined.
Abstract: The high temperature compressive strength of oxidized pellets in different atmospheres was tested by means of a self-made high-temperature compressive strength on-line test system.It is shown that the variation laws of high temperature compressive strength of ore pellets in neutral and oxidizing atmospheres are basically consistent.The strength of ore pellets increases with the increase of temperature below 800℃,but there is a significant decrease between 800℃ and 900℃.At the range from 900℃ to 1 100℃,the strength increases slightly with the increase of temperature.There is a sharp decline of strength above 1 100℃ and the strength nearly disappears at 1 200℃.As a whole the strength of ore pellets in neutral atmosphere is higher than that in oxidizing atmosphere.In reducing atmosphere,the strength of ore pellets decreases with the increase of temperature and reduction degree and almost disappears when the temperature reaches 1 100℃.The mechanism of the change in high temperature compressive strength of ore pellets was analyzed.
Abstract: The phases,size distribution and morphology of inclusions as well as the microstructure of low carbon steel which is complex deoxidized by Al-Ti-Mg were investigated by technically deoxidizing pure iron with Fe-50%Ti,Ni-16.7%Mg and Fe-70.74%Si.The experimental results show that in comparison with non-Ti-treated samples the total number of inclusions in the Ti-treated steel increases by 400 mm-2,meanwhile the size of inclusions decreases obviously.Comparing with Mg deoxidizing,the total number of inclusions in the Ti-Mg complex deoxidized steel increases by 200 mm-2.There is a large number of acicular ferrite in austenite grains after being Ti-treated.The distribution of acicular ferrite is the most uniform and no polygon ferrite was observed in the Al-Ti-Mg complex deoxidized steel.
Abstract: The effect of hot galvanizing processes on the mechanical properties and microstructure of non-Si and P-added TRIP steel was studied by using optical microscopy,transmission electron microscopy,X-ray diffraction and tensile test.It is shown that the steel with tensile strength over 780 MPa and percentage elongation after fracture over 24% can be obtained.The temperatures of intercritical annealing and isothermal bainitic transformation(IBT) have little influence on the mechanical properties,while IBT time plays significant contribution to them.When the IBT time prolongs from 20 s to 60 s,the sample reaches the best performance.Its yielding strength rises by 65 MPa,tensile strength decreases by 45 MPa,and elongation increases obviously from 23.01% to 27.56%,respectively.The microstructure of non-Si and P-added TRIP steel consists of ferrite,bainite,retain austenite and martensite.As the IBT time shortens,the amount and stability of austenite get decreased,the content of martensite increases markedly,and the mechanical characteristics of the steel transform from TRIP steel's to dual-phase steel's gradually.
Abstract: The electrochemical behavior and semiconductor properties of passive films formed on super 13Cr martensitic stainless steel in a corrosion solution which contains CO2 and Cl- soaked for 7d at 100,130,150 and 170℃ were examined using polarization curves and Mott-Schottky curves.The valence states of elements in the passive films were analyzed by X-ray photoelectron spectroscopy.It is shown that Mo and Ni in the forms of sulfides concentrate respectively in the surface layer of the passive films,but Cr in form of oxides enriches on the surface layer.The passive films formed at 100℃ and 130℃ are in possession of superior corrosion resistance,but the corrosion resistance of the passive films formed at 150℃ and 170℃ decreases.The reason for this phenomenon is concerned with the semiconductor properties of the passive films.A typical n-p-type semiconductor behavior is observed for the passive films formed at 100℃ and 130℃,the doping quantity increases with increasing temperature;but a p-type semiconductor behavior is observed for the passive films formed at 150℃ and 170℃.For this reason,the corrosion resistance of the martensitic stainless steel decreases with increasing temperature.
Abstract: The rafting procedure of γ' phase in single crystal DD402 for DD402/FGH95 diffusion couples bonded by hot isostatic pressing(HIP) was studied.A new rafting mechanism of γ' phase was suggested.The driving force of rafting γ' phase was analyzed and a physical model of the rafting procedure of γ' phase was constructed.The relations of the width of rafted γ' phase pieces with the original size,volume fraction and constitutional element diffusion flux of γ' phase were discussed in details.The results show that the rafted reason of γ' phase in the single crystal is the continuous directional growth of γ' phase driven by diffusion of its constitutional elements.The rafted process includes two stages,one is the directional connect of γ' particles,and the other is the plainness process of γ' pieces.The width and direction of rafted γ' pieces were closely related to the original size and crystal orientation of γ' phase.
Abstract: The effect of pulse current on the shape of non-metal phases in solid metals,such as Al-Si alloys and ductile cast irons,was studied by applying pulse current at room-temperature and high temperature and compared to normal heat processing.The results show that pulse current accelerates the granulation of coarse band-form eutectic silicon in the Al-Si alloy.The diameter of original graphite in the ductile cast iron treated by pulse current does not increase obviously,the average round-shaped degree of graphite increases a little,and some spherical graphite appears in the structure.The behavior of dislocations adjacent to non-metal phases and the diffusion of atoms by the action of pulse current are main reasons for the shape of non-metal phases.
Abstract: A burbling cooling technique used for preparing semi-solid alloys was presented.Water quenching specimens made of semi-solid AlSi9Mg alloy were prepared by which pin fins were put into a homemade sloping cooling device.The microstructures of the specimens were analyzed by the quantitative analysis technique.The influence of the shape,arrayed mode and arrayed pitch of pin fins on the microstructure of semi-solid AlSi9Mg alloy was studied.It is revealed that when the sectional shape of pin fins is water drop shaped,more α-Al phases with homogeneous microstructure and clear outline are obtained in the semi-solid alloy melt,showing spherical or nearly spherical shapes.The water quenching characteristics are the primary solid rate of 53.54%,the grain size of 5.59 μm and the shape factor of 0.61.Different arrayed modes and different arrayed pitches of pin fins have great influence on the microstructure of the semi-solid AlSi9Mg alloy melt.The cross array has more advantages over the order array under the same conditions,and the ideal spacing is the one with line spacing S=15 mm and column spacing L=40 mm.
Abstract: The as-cast microstructure and phase structure of ZnAl10Cu2 alloy were observed and analyzed by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and X-ray diffraction(XRD).The formation mechanism of the structures was also studied.It is shown that the solidification of cast ZnAl10Cu2 alloy is consisted of primary α1 dendrites and rod-like eutectic(α2 + β) surrounding primary α1 dendrites.There occur eutectoid reactions in primary α1 phase and α2 phase in the eutectic structure during the subsequent cooling process,and lamellar(α + η) eutectoid organization forms.The retained α1 and α2 phase precipitate discontinuously and form granular precipitates in room temperature aging.The primary α1 is the Al-rich(Al forms solid solution with Zn) and strengthening phase,with the crystal structure of a face-centered cubic lattice.And for β,the crystal structure of the Zn-rich phase is a hexagonal lattice.
Abstract: Using Bi(NO3)3·5H2O and Ti substrates as raw materials and absolute ethyl alcohol as a solvent,oriented Bi0.5Na0.5TiO3(BNT) ceramics were synthesized by solvothermal method.The phase,micro-mophology and composition of BNT ceramics were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM) and energy dispersive spectroscopy(EDS).The effects of factors such as NaOH concentration,[Bi3+] concentration,surfactants and solvents on the grain phase,micro-mophology and composition of BNT ceramics were systematically studied.The results show that oriented BNT ceramics are successfully obtained when the NaOH concentration,the[Bi3+] concentration,the addition of polyethylene glycol(PEG) and the solvent are 1 mol·L-1,0.1 mol·L-1,1 to 6 mL and absolute ethyl alcohol,respectively.The average size of the BNT grains is in the range of 10 to 20 μm.
Abstract: Based on analyzing the chemical composition,mineral composition and thermal stability of red mud,the preparation of ceramsite was investigated with calcite itself in red mud or added sodium nitrate as a foaming agent.Main components of the obtained ceramsite were analyzed by X-ray diffraction(XRD) and the internal structure was observed by scanning electron microscopy(SEM).The results show that with calcite itself as a foaming agent,the ceramsite with a bulk density of 1.43g·cm-3,a water absorption rate(WAR) of 1.23% and a cylinder compressive strength(CCS) of 22.14 MPa is prepared when the mass ratio of red mud/waste glass/bentonite is 74:15:11.However the bulk density is obviously decreased by adding sodium nitrate.The ceramsite with a bulk density of 1.28g·cm-3,a WAR of 1.54% and a CCS of 12.03 MPa is prepared when the mass ratio of red mud/waste glass/bentonite/sodium nitrate is 70.0:14.2:10.2:5.6.Crystalline phases present in the obtained ceramsite are mainly gehlenite,different from calcite in red mud based on XRD data.SEM images indicate that the majority of pores in the obtained ceramsite are sealed,and when sodium nitrate is used as a foaming agent,the porosity is higher in comparison with calcite in red mud,and the internal pore size is more uniform.
Abstract: Nanometer zinc oxide was prepared through oxygen control by vacuum using hot galvanizing dross as raw materials and air as an oxygen source,and the product purity is up to 99.98%.The influences of the reaction temperature and the vacuum degree of the reaction system on the morphologies of the product were investigated.The behavior of main impurity elements and their influence on the product quality were studied under different oxidation conditions.It is shown that the reaction temperature and the vacuum degree of the reaction system have great influence on the morphologies of the product.The product is mostly hexagonal wurtzite structure of nanometer tetrapod ZnO,the needles are slender,and the length-to-diameter ratio is large at suitable temperature and vacuum degree.The different behaviors of impurity Fe and Pb affect the product quality in different ways under different oxidation conditions.The joining of Fe into the product is mainly due to mechanical entrainment of zinc and the positive bias effect of Fe-Zn systems;however,Pb joins in the product because of its evaporation pressure and the positive bias effect of Pb-Zn systems.
Abstract: Morphological and structural changes of ethylene-propylene-diene monomer(EPDM) in indoor-accelerated aging test and atmospheric exposure test were investigated by gloss meter,scanning electron microscopy(SEM) and Fourier transform infrared spectroscopy(FTIR).Correlation analysis was applied to discuss the outdoor and indoor apparent aging properties of EPDM.The results show that the gloss does not change in salt-fog test.In fluorescent UV test,the gloss decreases rapidly in the initial stage of aging and then reaches a plateau.The gloss changes inconspicuously in the initial stage of aging and then decreases with the aging time prolonging in atmospheric exposure test in the Xisha islands.The trend of gloss in indoor UV and salt-fog composite circulation experiment is similar to atmospheric exposure test in the Xisha islands.Atmospheric exposure test in the Xisha islands and indoor UV and salt-fog composite circulation experiment have a better correlation.Based on the analysis of gloss,the accelerated aging multiple of indoor UV and salt-fog composite circulation experiment is 25 to 26.FTIR spectra imply that β-diketone may form after EPDM is exposed to the artificial weathering environment produced by indoor UV and salt-fog composite circulation experiment and atmospheric exposure test in the Xisha islands.β-diketone is not formed in the salt-fog test condition.
Abstract: In order to study the effects of strain test methods,loading frequency,testing temperature and stress amplitude on the dynamic compression elastic moduli of asphalt mixtures,the dynamic compression elastic moduli of two kinds of commonly asphalt mixtures,AC-16 and AC-20,were studied by using an MTS dynamic pavement material test system.The relation between the above factors and the dynamic compression elastic modulus as well as the relation between the static and dynamic compression elastic modulus was established.According to the analysis of test results,the data tested by the side method much approach to the recommended values in the specification and the side method can also eliminate the contact error of the specimen caused by the top surface method.It is recommended that the side method is firstly chosen to use in the static and dynamic modulus test.While an appropriate load frequency is selected in the dynamic test,the deviation coefficient of test results should be controlled below 20%.
Abstract: A comprehensive mathematical model was established to develop a new iron-making process for a top gas recycling and oxygen blast furnace.The model consists of the calculation equations for gas composition of each area in the blast furnace,the thermal equilibrium model on the top skip area of the blast furnace,the thermo-chemical balance model,and the stack efficiency model.Operating parameters for the new iron-making process were calculated with the model.The results show that the coke rate and the coal rate of the new iron-making process are both 200 kg·t-1,and in comparison with a traditional blast furnace,the fuel ratio decreases by 22.9%.In addition,the tuyere circulation gas quantity has great influence on the theoretical combustion temperature.When the tuyere circulation gas quantity increases by 10m3·t-1,the theoretical combustion temperature decreases by 17.6K.Furthermore,the model could be applied to calculate the operating parameters when the raw materials and fuel conditions are different,and the change laws of operating parameters under the same raw materials and fuel conditions also could be studied with this model.
Abstract: The principle and characteristic of waste heat recovery with heat pipes were analyzed in combination with the present condition of utilizing electric arc furnace(EAF) flue gas at home and abroad.The structure character,technical processes,and key parameters of this system were studied comprehensively.How to make high quality steam to meet the demand of VD(RH) furnaces was also discussed.A practical application of waste heat recovery in 50t EAF in Laiwu Steel shows a good prospect of the technology.
Abstract: With the concept of optimal classification lines,a pattern recognition method,which uses interface geometric discriminant to generate a pattern classifier,was proposed.Major procedures of the method include:mapping multidimensional inputted characteristic vectors of different pattern classes to a 2-dimensional(2D) discriminant space with a BP neural network which is characterized by its high nonlinear mapping capability,extracting a polygon axis of the polygon which is formed at the interval clearance space among pattern classes,and constructing a decision-making boundary for pattern recognition by extending polygon axes to all discriminating domains.The method was tested in a case study of fault diagnosis for double row tapered roller-bearings used in railway wheels.The result shows that the proposed method can construct decision-making boundaries for different fault patterns on a 2D discriminant space,which provides a condition to operators for intuitive recognition of fault classifications in practice.
Abstract: Acoordination factor for the sequence of plans was proposed aimed to coordinating the casting production plan with the hot rolling production plan in an integrated production process.An optimization model of the hot-rolling batch plan available to improve the direct hot charging rolling(DHCR) proportion was established.On the basis of meeting the requirements of the hot rolling process,the model considers well the coordination of the casting production plan and the hot rolling production plan.A modified genetic algorithm,the two-exchange crossover heuristic algorithm,was used to solve the model.Finally,two slab groups which are large batch quantity with seldom types and small batch quantity with multiple types were simulated in the 2 250 mm hot rolling line and the 1 580 mm hot rolling line in a steel plant.The results show that the model could greatly reduce the waiting time of slabs caused by the casting slab sequence conflicts before entering the reheating furnace,and the DHCR proportion is increased correspondingly.
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
