The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite. The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol⁻¹ in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.

By using the fault tree analysis in reliability theory as the systematical analysis approach, the dust suppression mechanism in a spray system with wetting agent is shown in a logic tree and some graphical models. From these diagrams, all factors related to the spray system and their cause-and-effect relationship can be seen clearly. Based on the built logic tree, several mathematical models and new ideas for expressing the dust suppressing efficiency in the spray system are put forward. The significance of all factors related to the efficiency of suppressing dust is qualitatively described. Furthermore, the new concepts, such as, the effective reaction time between dust particle and droplet, the expansion phenomenon of laden dust droplet, the functions of volatile and the relative size distribution efficiency of wetting agent are presented. All this richenes the existing mechanism of dust abatement by spraying wetting agent. At last, several problems that need to be further investigated are also suggested in the paper.

By analyzing the metallogenic conditions and prospecting marks of F₈ fault belt in Shiujingtun Gold Mine, the geochemical samples were collected along F₈ fault belt and prospecting profile normal to the F₈ fault belt. Gold and its indicator elements were tested with X-ray fluorescence spectrometry and the content distribution diagram of Au, Ag, Hg and As along the F₈ fault belt was performed. The geochemical primary halo model and the Grey system model of F₈ fault belt are established. With these element distribution features and models, the blind ore bodies in the F₈ fault belt were predicted. Engineering prospect shows that the industrial orebodies have been discovered and the prediction results are dependable.

A new test method—the load relaxation test after the peak value, was used to investigate rockburst proneness. Two new concepts—fountain and inductive rockbursts, were proposed to distinguish two kinds of rockbursts. The breaking process of rock, mutation condition and occasion of rockburst and source of kinetic energy of rockburst were discussed.

The paper presents a novel material preparation technology—Solid-liquid mixed casting technology. In the technology, large amounts of homogeneous alloy powder or heterogenous powder with perfect wettability are added into the superheated melt. After strong agitation, the mixed melt can be cast or hot processed. Applying solid-liquid mixed casting, three kinds of Al-Si alloys were investigated. The results show that, when the mass of powder accession to alloy melt is about 1, the mean size of primary Si in hyper-eutectic alloy can be controlled at less than 5 µm; and the mean grain size of α phase in hypo-eutectic alloy is less than 10 µm. This technology has the advantage of preparing material with very fine microstructure by fairly simple casting process, and may be a new practicable and valuable metal preparation technology.

The electronic structures of pure Sc and Y metals with hcp structure have been determined by one-atom (OA) theory, which are [Ar](3d_c)^1.3315(4s_c)^0.9050(4s_f)^0.7635 and [Kr](4d_c)^1.2930(5s_c)^0.9470(5s_f)^0.7600. According to their electronic structure, their potential curves, cohesive energies, lattice constants, elasticity and the temperature dependence of linear thermal expansion coefficients have been calculated. The electronic structures and characteristic properties of these metals with bcc structures and primary liquids have also been studied, which has supplied the structural parameters and property parameters of Sc and Y with different crystal structures and also supplied a series of complete data for the theoretical design of Sc and Y based materials.

Blended elemental Ti-34% Al powders (mass fraction), containing 1.5% TiC, were hot isostatic pressed to prepare TiAl alloys. The effects of HIPing pressure on the sintered density, microstructure, constitutions phase were studied in details. The results show that the density of TiAl alloy increases repaidly with the increase of the HIPing pressure. At the same time, with the increase of pressure, the Ti₃Al phase in matrix disappears. TiC reacts with other substance, forming Ti₂AlC phase, which precipitates at grain boundaries. With the increase of hot isostatic pressing (HIPing) pressure, the shrinkage of the alloys increases, the fine spherical Ti₂AlC phase can meet together and forms a needle-shape Ti₂AlC, and the amount of needle-shaped Ti₂AlC phase increases. The composite material of TiAl containing C can be made easily by HIPing technology.

A method, doping WC with La(NO₃)₃, of producing cemented carbide with rare earth was introduced. The effects of lanthanum on the mechanical properties and microstructure of WC-9(Co-75%Ni) cemented carbide were studied and a rock drilling experiment was carried out. The experimental results show that both transverse rupture strength (TRS) and hardness of WC-9(Co-75%Ni) rare earth cemented carbides can match that of WC-9Co cemented carbide, when La₂O₃/(Co + Ni) ratio is 0.3%, the abnormal growth of WC grain in the cemented carbide can be restrained effectively, the homogeneity of grain size in microstructure and the wear resistance are improved, which can be matchable to that of WC-9Co cemented carbide for mining.

A novel type of thermal stabilizer-antimony tris (thioethyl stearate) (ATS) was synthsized. Its thermal stability was measured by heat-aging oven test when incorporated into PVC. ATS was synthesized from stearic acid, antimony trioxide and 2-mercaptoethanol in two steps. The reaction conditions of synthesis were optimized through orthogonal test. Experimental results show that the molar ratio of stearic acid and antimony tris (2-hydroxyethylthiolate) was 1.2, adding 0.6% tetra-n-butyl titanate as catalyst and xylene as azeotropic solvent, heating and refluxing for about 4 h, and the yield of ATS is 83.9%. The thermal stability time is about 40 min(at 200 °C) when added 2phr(per hundred resin) in PVC. The thermal stability of ATS is better than that of Ca-Zn complex and basic lead stabilizers, and equal to that of dibutyltin dilaurate.

A new process of separating sulfur with different valance from polysulfide mixtures was developed. Sulfide, sulfite and sulfur were separated by adding acetic acid in one step. The polysulfide mixture, sulfite solution and sulfur were oxidized to sulfate by hydrogen peroxide. The products were measured by X-ray Fluorescence Spectrometer(XRF) using filter method preparative specimen. The measurement needs only one set of standard sample. The effects of temperature and pH values on the separation were discussed. The results show that the recoveries range from 98.0% to 101.3% of sulfidic sulfur S(-II), 97.0% to 103.0% for sulfite S(IV) and 98.4% to 100.4% for polysulfidic sulfur S(0).

Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full-scale furnace fired tangentially at four corners is adopted. “κ-ɛ” turbulence model is used for the gas phases and a stochastic approach based on the Lagrangian technique is used for particle phases. Two-competing reactions model for the coal devolatilization and PDF (the probability density function) method for the combustion of the gas phases are employed. In the numerical simulations, assuming the air distribution of second port level is of pagoda, waist drum and uniform type. The results show that pagoda type air distribution is advantageous to ignition and smooth combustion of pulverized coal, and suitable to inferior coal combustion in practice. In the present furnace, the igniting distance at 1st and 3rd corner is longer than that at 2nd and 4th corner. The results from numerical calculations are in good agreement with those of observed in practice.

High temperature air combustion (HTAC) is an attractive technology of saving energy and controlling environment. The mathematical models of turbulent jet flame under the highly preheated air combustion condition are conducted in the paper. The mixture fraction/probability density function model is employed. The results show that the maximum flame temperature is decreased, the temperature in the HTAC furnace is more uniform than that in the conventional furnace, and the NO_x emission is low. The numerical results are partially validated by some experimental measurements.

The effect of key parameters on fatigue life of common metallic components, e.g. steel, aluminium alloy, has been analysed quantitatively. The influential coverage and degree of these parameters have been investigated systematically, some phenomena which can’t be discovered with qualitative analysis method have been revealed, a series of valuable conclusions has been obtained, which would be very beneficial to fatigue-resistant design and improvement of anti-fatigue ability of metallic components.

The paper probes into a probable condition that causes temper mill chatter from aspect of electromechanical coupling of complex electromechanical system, and mainly studies the effect of temper mill electrical driving system harmonic current on the main motion of temper mill set. Aiming at the electrical driving system of CM04 temper mill, the effect of harmonic current is analyzed and evaluated according to different load. Combining the features of CM04 temper mill’s structure and its working state, the paper discusses in every detail how the harmonic current in main circuit, which can be regarded as a disturbance via feedback control circuit, influences main motion of temper mill set.

Many industrial processes such as heating furnaces have over-damping dynamic characteristics. Based on an innovative impulse response model, a method of identification and control for the over-damping plant is introduced in the paper. The number of parameters of the model is much less than conventional impulse response model. The model based on tuning procedure of numerical optimum PID controller parameters is presented. For an actual instance, a large-scale airflow circulatory resistance furnace control system with cascades of time-delays is developed. In the system, the optimum PID control is used in the inner loop. A nonlinear PI compensation control is applied in the outer loop. The coordinating control among each output is realized by a fuzzy control strategy. A process surveillance organization monitors running situation of system and tunes controller parameters.