FeAl/TiC composites were fabricated by reactive hot pressing blended elemental powders. The TiC content was varied from 50% to 80% (volume fraction) and the aluminum content in the binder phase was changed from 40% to 50% (mole fraction). The effects of these compositional changes on the densification process and mechanical properties were studied. The results show that with the increase of TiC content, densities of the composites decrease due to insufficient particle rearrangement aided by dissolution — reprecipitation reaction during hot pressing. Closely related with their porosities and defect amount, the hardness and bend strength of the composites show peak values, attaining the highest values with TiC content being 70% and 60%, respectively. Increasing the aluminum content is beneficial to the densification process. But the hardness and bend strength of the composites are reduced to some extent due to the formation of excessive oxides and thermal vacancies.

The oxidation of the ternary alloy Ni-15Cu-5Al in 1×10⁵ Pa pure oxygen at 700 °C and 800 °C was studied. The results show that the behavior of the Ni-rich alloy is similar to that of the binary Ni-Al alloy with the same Al content in the form of an external NiO layer coupled to the internal oxidation of aluminium. The presence of 15% (mole fraction) Cu cannot modify substantially the values of relevant parameters affecting the transition from the internal to the external oxidation of aluminium. The presence of 5% Al reduces the oxidation rate of the corresponding Ni-Cu alloy during the whole oxidation stages, though 5% Al is still insufficient to form protective external alumina scales.

The restoration mechanisms for static recrystallization of work-hardened austenite were investigated by using double-pass compression tests performed on medium-carbon steel containing chromium and molybdenum. The softening fraction was defined by 2% offset method. The results show that Avrami exponent of about 0.21 is insensitive to deformation temperature, indicating that the action of steel grade should be considered. The time of 50% recrystallization (t_0.5) decreases noteworthily with the increase of deformation temperature. Apparent activation energy for static recrystallization of 195 kJ/mol, which is close to that of vanadium microalloyed steel, is obtained by calculating. The increasing trend of the driving force for recrystallization is opposite to that of the deformation temperature, which is attributed to the number of operative slip system increasing as temperature increasing.

In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by flow coat method on the surface of industrially pure titanium TB1-0. The effects of nano-size nickel particles on the wear resistance and high temperature oxidation resistance of coating substrate system were investigated through oxidation kinetics experiment and wear resistance test. The morphologies of the specimens were examined by means of optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the high temperature ultra fine ceramic coating has notable protection effect on industrially pure titanium TB1-0 from oxidation. The oxidation and wear resistance properties of the coating can be effectively improved by adding nano-size nickel particles. The oxidative mass gain of the specimen decreases from 11.33 mg · cm⁻² to 5.25 mg · cm⁻² and the friction coefficient decreases from 1.1 to 0.6 by adding nano-size nickel particles, and the coating containing 10% (mass fraction) nano-size nickel shows the optimum properties.

The surface morphology of alloy layer of tinplate was studied by means of scanning electron microscopy. By using the layer on layer debonding technology of glow discharge spectrum, the contents of C and O at the boundary of alloy layer and black plate were analyzed. And the corrosion characteristic of cavity of tinplate alloy layer was studied on-line and in-situ by means of electrochemical atomic force microscope. The corrosion depth of cavity of alloy layer in-situ after different corrosion time was measured. The results show that the cavity of alloy layer is a critical factor causing rapid decline of corrosion resistance of tinplate, and the formation of cavity of alloy layer is due to incorrect pretreatment of black plate before electrotinning. The cavity of alloy layer is the internal factor causing pitting corrosion of tinplate when the tinplate is applied to food packaging material. And the dynamic equation of pitting corrosion generated in the cavity of alloy layer conforms to logarithm law.

Microstructures and mechanical properties of Mg-2.0%Ce-0.7%Zn-0.7%Zr alloy were studied. The results of scanning electron microscopy show that Mg₁₂Ce phase mainly distributes at the grain boundaries. The fine Mg₁₂Ce phase can apparently elevate recrystallization temperature by preventing the grain boundary migration. No dynamic recrystallization occurs during the hot-extrusion. The mechanical properties of as extruded specimens are σ_b=278.5 MPa, δ=12.0%, while those of the specimens annealed at 250 °C for 100 h are σ_b=272.6 MPa, δ=11.3%, which indicate that the alloy has good mechanical properties at room temperature.

Highly ordered and porous anodic aluminum oxide templates were prepared. The ordered copper nanowires arrays were assembled in nano-holes of the template by alternating current electrodeposition at lower voltage. The morphologies of template and copper nano-wires arrays were characterized by means of field emission scanning electron microscope (FESEM) and the crystal structure of copper nano-wires was determined by means of X-ray diffraction. The results indicate that copper nano-wires hold the preferred crystalline orientation along (111), (200), (220) and (331) crystal faces during growth, and the growth of copper nano-wires in the nano-holes of the template is homogenous and continous.

Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans (T. f.) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h) is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe(II) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe(II), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.

The performance of hydroxamic polyacrylamide (HPAM) in mineral flotation was tested on the samples of calcite, diaspore and pyrite. It is found that HPAM expresses intensive depression on pyrite and can be used as effective depressants for pyrite. The depression mechanism of HPAM to pyrite was investigated by the determination of contact angle, zeta potential, adsorptive capacity for collectors and infrared spectrum. A lower contact angle, more negative zeta potential, less xanthate adsorptive capacity, and the formation of chemical bonding were determined, which reveals that the strong chemical interactions exist between HPAM and pyrite surface. The group electronegativity of HPAM was calculated to explain the differences of interaction between reagent and minerals.

Pyrite (FeS₂) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS₂(100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe²⁺ and S²⁻ have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS₂ surface acts as peroxides rather than O₂.

The removal of phosphate from municipal sewage by high gradient magnetic separation using aluminium sulphate as precipitating agent and Fe₃O₄ as seeding material was studied. The effects of aluminium sulphate, Fe₃O₄, magnetic field intensity, pH value and flow-rate of sewage on phosphorus removal rate were investigated. The results show that addition of 200 mg/L Al₂(SO₄)₃ · 18H₂O and 300 mg/L Fe₃O₄, magnetic field intensity of 200 kA/m, pH value of 4.5 – 7.0 and flow-rate of 6.15 cm/s are both efficient and economic technical parameters for removal of phosphate. The pH value has a tremendous effect on the removal of phosphate. In the pH range of 4.5–7.0, more than 95% phosphate can be removed. Theoretical analysis indicates that the solubility of AIPO₄ is minimum at pH 4.0 – 7.0 and the electrostatic attractive force between AIPO₄ and Fe₃O₄ is maximum at pH 4.5 – 6.5.

Natural sepiolite was treated with HCl solution to change its surface and internal structure and the structure of sepiolite was cracked to produce SiO₂ when the concentration of HCl is more than 2 mol/L. The Mo-Bi-Fe-Co-V-Sb-O/sepiolite catalyst was prepared through impregnation — precipitation method and characterized by means of X-ray diffraction, scanning electron microscopy and energy dispersive spectrum techniques. The effects of temperature, volume fractions of NH₃ and O₂, and space velocity of feed gas on catalytic activity were evaluated in a fixed bed reactor. The results show that propane conversion of 82% and selectivity to acrylonitrile of 38% can be obtained at 490 °C, V(C₃H₈) : V(NH₃) : V(O₂)=1.00 : 1.05 : 2.50 and space velocity of 3000 cm³ · g⁻¹ · h⁻¹.

TiB₂/C cathode composites with various contents of TiB₂ were prepared and their characterizations were observed and compared. The expansion of samples due to sodium and bath penetration was tested with a modified laboratory Rapoport apparatus and the appearances of the cut sections of specimens after electrolysis were studied. The results show that the mass of TiB₂/C cathode composites with mass fraction of TiB₂ less than 70% appreciably increases, but that of the composites with mass fraction of TiB₂ more than 70% decreases slightly after being baked. The resistance to sodium and bath penetration of TiB₂/C cathode composites increases with the increase of TiB₂ content, especially in the composites with high TiB₂ content. TiB₂/C cathode composites have high resistance to the penetration of sodium and bath as well as good wettability by molten aluminum, and keep integrality and have little change of appearance after electrolysis, which indicates that TiB₂/C cathode composites can be used as inert wettable cathode for aluminum electrolysis.

In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl₃ leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process. The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl₃ concentration results in a sharp increase in the output of the leaching cell when c(FeCl₃) is less than 0.1 mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl₃ is 3.0 mol/L. Temperature influences electrogenerative leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34. 63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni²⁺ is 29.3% after FeCl₃ electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.

Simultaneous equilibrium was applied to the thermodynamic analysis and calculation of Bi(III)-X(Cl⁻, NO₃⁻)-H₂O systems, based on which the diagrams of the logarithm of equilibrium concentration of Bi(III) of series precipitation vs pH value of these two systems at 25 °C were obtained, and the pH ranges of the stable zones of various precipitations were analyzed and determined. In Bi (III)-Cl⁻-H₂O system, the variations of c₀ (Bi³⁺) and c₀(Cl⁻) have little effect on the equilibria of Bi(OH)₃-solution and BiOOH-solution, but has great influence on the equilibrium of BiOCl-solution. However, in Bi(III)-NO₃⁻-H₂O system, the variations of c₀ (Bi³⁺) and c₀ (NO₃⁻) have little effect on equilibria of Bi(OH)₃-solution, BiOOH-solution and Bi₂O₃-solution. When pH value is high, Bi₂O₃ is the thermodynamic stable phase, its stable zone is the widest, almost including the stable zones of BiOCl or BiONO₃, Bi(OH)₃ and BiOOH. Bi(OH)₃ cannot be obtained from Bi(III)-Cl⁻-H₂O system, even strong alkaline media. Bi₂O₃ can be obtained from the solution directly, and highly pure BiOCl or BiONO₃ can also be obtained through strictly controlling pH value.

Co/Al₂O₃ Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen temperature programmed desorption (H₂-TPD) and O₂ titration. Co-support compound formation can be detected in catalyst system by XRD. For the Co/Al₂O₃ catalysts with low cobalt loading, CoAl₂O₄ phase appears visibly. Two different reduction regions can be presented for Co/Al₂O₃ catalysts, which belong to Co₃O₄ crystallites (reduction at 320°C) and cobalt oxidetallite size. The reduced Co/Al₂O₃ catalysts have two adsorption sites, and cobalt loading greatly influences the adsorption behavior. With the increase of cobalt loading, the amount of low temperature adsorption is increased, the amount of high temperature adsorption is decreased, and the percentage reduction and cobalt crystallite size are increased.

The effects of components and their ratio of groups on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd²⁺, Pb²⁺ and Hg²⁺). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified groupting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg²⁺ > Pb²⁺ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.

Based on the study of the slope with gently granular structure in Xingqiao open mine, a new safety cleaning bank mode for steep slope mining was developed, including setting up dint cut, and forming natural retaining wall based on the character of gentle incline slope. It can effectively eliminate the impact of sliding body on the bottom working place and slope body, reduce the dilution of ore, keep rainwater from upper steps away, decrease influence of the weak intermediate layer, and cut cost of disposal waste rock. The safety and reliability of the mode were analyzed and verified from 3 aspects: static load calculation, ANSYS simulation of dynamic loading and spot experiment. The result of static loading calculation shows that the retaining wall can support accumulation and extrusion of granular body, and the glide or overturn disaster will not take place. The simulations of dynamic loading show that the retaining wall remains stable until sliding body collapses from 360 m (10 sublevels). Only one new safety cleaning bank in each 1–5 sublevels can fully meet the need of engineering. The new mode sustains steep slope mining, increases the angle of ultimate slope, and reduces invalid overburden amount of rock by 3%–5%. The result of spot experiment has verified the exactness of the above calculations and simulations.

Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was exploded, two different radial strain waves were sequentially recorded by a strain gage at a distance of 80 mm from the center of charge. Through the attenuation formula of the maximum compressive strain(ɛ_max), the distribution of ɛ_max and its strain rate(ɛ) between the charge and gage were obtained. The effect of the two waves propagating outwards on the radial fracture of surrounding media was discussed. The results show that the two waves are pertinent to the loading of shock energy (E_s) and bubble energy (E_b) against concrete surrounding charge, respectively. The former wave lasts for much shorter time than the latter. The peak values of ɛ_rmax and ɛ of the former are higher than those of the latter, respectively.

Slope stability is of critical importance in the process of surface-underground mining combination. The influence of underground mining on pit slope stability was mainly discussed, and the self-stabilization of underground stopes was also studied. The random finite element method was used to analyze the probability of the rock mass stability degree of both pit slopes and underground stopes. Meanwhile, 3D elasto-plastic finite element method was used to research into the stress, strain and rock mass failure resulting from mining. The results of numerical simulation indicate that the mining of the underground test stope has certain influence on the stability of the pit slope, but the influence is not great. The safety factor of pit slope is decreased by 0.06, and the failure probability of the pit slope is increased by 1.84%. In addition, the strata yielding zone exists around the underground test stope. The results basically conform to the information coming from the field monitoring.

Based on the modified plastic strain energy approach, an elasto-plastic constitutive modeling for sand was proposed. The hardening function between the modified plastic strain energy and a stress parameter was presented, which was independent of stress history and stress paths. The proposed model was related to an isotropically work-hardening and softening, non-associated and elasto-plastic material description. It is shown that the constitutive modeling, the inherent and stress system-induced cross-anisotropic elasticity is also considered. The constitutive model is capable of simulating the effects on the deformation characteristics of stress history and stress path, pressure level and anisotropic strength.

A mechanical model for strain softening pillar is proposed considering the characteristics of progressive shear failure and strain localization. The pillar undergoes elastic, strain softening and slabbing stages. In the elastic stage, vertical compressive stress and deformation at upper end of pillar are uniform, while in the strain softening stage there appears nonuniform due to occurrence of shear bands, leading to the decrease of load-carrying capacity. In addition, the size of failure zone increases in the strain softening stage and reaches its maximum value when slabbing begins. In the latter two stages, the size of elastic core always decreases. In the slabbing stage, the size of failure zone remains a constant and the pillar becomes thinner. Total deformation of the pillar is derived by linearly elastic Hooke’s law and gradient-dependent plasticity where thickness of localization band is determined according to the characteristic length. Post-peak stiffness is proposed according to analytical solution of averaged compressive stress-average deformation curve. Instability criterion of the pillar and roof strata system is proposed analytically using instability condition given by Salamon. It is found that the constitutive parameters of material of pillar, the geometrical size of pillar and the number of shear bands influence the stability of the system; stress gradient controls the starting time of slabbing, however it has no influence on the post-peak stiffness of the pillar.

Using hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle as a simulation example, the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle were simulated and discussed with SIMULINK software and hydraulic control theory. The results show that the dynamic characteristics of hydraulic power steering system are improved obviously by using bladder accumulator, the hydraulic power steering system of model EIMCO 922 load-haul-dump vehicle generates vibration at the initial stage under the normal steering condition of pulse input, and its static response time is 0.25 s shorter than that without bladder accumulator. Under the normal steering working condition, the capacity of steering accumulator for absorbing pulse is directly proportional to the cross section area of connecting pipeline, and inversely proportional to the length of connecting pipeline. At the same time, the precharge pressure of nitrogen in steering accumulator should be 60%–80% of the rated minimum working pressure of hydraulic power steering system. Under the abnormal steering working condition, the steering cylinder piston may obtain higher motion velocity, and the dynamic response velocity of hydraulic power steering system can be increased by reducing the pressure drop of hydraulic pipelines between the accumulator and steering cylinder and by increasing the rated pressure of hydraulic power steering system, but the dynamic characteristics of hydraulic power steering system in load-haul-dump vehicle have nothing to do with the precharge pressure of nitrogen in steering accumulator.

The robustness analysis problem of a class of nonlinear descriptor systems is studied. Nonlinear matrix inequality which has the good computation property of convex feasibility is employed to derive some sufficient conditions to guarantee that the nonlinear descriptor systems have robust disturbance attenuation performance, which avoids the computational difficulties in conversing nonlinear matrix and Hamilton-Jacobi inequality. The computation property of convex feasibility of nonlinear matrix inequality makes it possible to apply the results of nonlinear robust control to practice.

An on-line forecasting model based on self-tuning support vectors regression for zinc output was put forward to maximize zinc output by adjusting operational parameters in the process of imperial smelting furnace. In this model, the mathematical model of support vector regression was converted into the same format as support vector machine for classification. Then a simplified sequential minimal optimization for classification was applied to train the regression coefficient vector a–a* and threshold b. Sequentially penalty parameter C was tuned dynamically through forecasting result during the training process. Finally, an on-line forecasting algorithm for zinc output was proposed. The simulation result shows that in spite of a relatively small industrial data set, the effective error is less than 10% with a remarkable performance of real time. The model was applied to the optimization operation and fault diagnosis system for imperial smelting furnace.