Advanced Materials Research Vols. 756-759

Abstract: The gold ore which contained 4.73 g/t Au was selected from carlin-type gold deposits in Guizhou. Three experiments on the gold ore were carried out. They were direct cyanide leaching, oxidizing roasting-cyanide leaching and flotation-oxidizing roasting-cyanide leaching. The experiments revealed that with the third process, ideal production index were obtained. The optimum conditions were confirmed: combined collector ammonium dibutyl dithiophosphate dosage was 60 g/t and butyl xanthate dosage was 120 g/t. Sodium cyanide dosage was 7000 g/t. As a result, we obtained satisfying selecting targets: The grade of gold was 42.0 g/t in the flotation concentrate. The gold leaching rate was up to 96.18%, and gold recovery was 88.23% after cyanide leaching. It was of important effect on decreasing resources waste and reducing environment pollution to research the project.

Abstract: In this paper, setting up a mathematical model about LCM process based on the theory, which contains a sink term in the mass balance equation of the fluid dynamics. In two-dimensional mold, the finite element/control volume method is used to simulate the flow front and pressure distribution of the flowing resin in single-scale and dual-scale porous media at constant pressure.

Abstract: This article briefly describes the composite materials and their excellent physical and chemical properties, the application of resin-based composite materials in the coal mine are emphatically introduced; and the application of rubber-based, cement-based composite materials in coal mine are briefly introduced, pointed out that the development and application of composite materials in coal production in China has great potential and broad development prospects.

Abstract: Response Surface Methodology (RSM) was used to study the relationship between the strength properties of poly ( p-phenylene terephthalamide)-PPTA paper and the preparation parameters, such as hot pressing temperature, hot pressing pressure, proportion of PPTA short-cut fiber and beating degree of PPTA-pulp. The results showed that: hot pressing temperature, hot pressing pressure have highly significant influences on the tensile strength and wet strength. The proportion of PPTA short-cut fiber has significant effects on the tensile strength and wet strength. The beating degree of PPTA-pulp also affected the tensile strength significantly. At the same time, the tensile strength was significantly influenced by the interaction between hot pressing temperature and the proportion of PPTA short-cut fiber as well as the interaction between hot pressing temperature and the beating degree of PPTA-pulp. The interaction between hot pressing temperature and hot pressing pressure has significant influences on wet strength, whereas the other factor interactions were not significant. The quadratic formula was established by optimizing the results of multiple regressions. And the model was highly consistent with the experiment. This model could be used to analyze and predict the main strength properties of PPTA paper and also might be used to optimize the production process of PPTA paper and control its quality.

Abstract: Electroless nickle coating with plain and high binding force was obtained in this experiment .the samples were heat treated and diffused, then microstructure and transformation was investigated by optical microscope and scanning electron microscope. The hardness, binding force, wear and corrosion resistance are tested, the reasonable heat treatment process is gained. Hardness is increased after eletroless nickel plating and heat treatment compared with the matrix. The adhesion of sample heat treated at 400°C is highest, the weight loss and friction coefficient is lowest, the corrosion resistance is best..

Abstract: Dynamic analysis is performed for a crack in a functionally graded materials layer for plane problem using shear stress. The material properties of the functionally graded materials layer vary randomly in the thickness direction, and the cracks are parallel to the materials faces. A pair of dynamic loadings applied on the elastic planes faces are treated as stationary stochastic processes of time. By dividing the functionally graded materials layer into several sub-layers, this problem is reduced to the analysis of laminated composites containing a crack, the material properties of each layer being random variables. A fundamental problem is constructed for the solution. Based on the use of Laplace and Fourier transforms, the boundary conditions are reduced to a set of singular integral equations, which can be solved by the Chebyshev polynomial expansions. The stress intensity factor history with its statistics is analytically derived. Numerical calculations are provided to show the effects of related parameters.

Abstract: This paper introduces the zinc oxide ore flotation process and flotation reagents; analyses the reasons why zinc oxide ore is difficult to concentrate; introduces new techniques of zinc oxide ore dressing; prospects the development trend of zinc oxide ore dressing.

Abstract: Austenization is an important stage during the quenching-tempering heat-treatment process of X65 microalloyed pipeline steel, because it can influence the development of final microstructure and mechanical properties. In this paper, a detailed investigation was carried out on the austenizing transformation process in X65 microalloyed pipeline steel using high-resolution dilatometric technique and microstructure observations. According to the obtained dilatometric curve during continuous heating, the austenizing transformation process in X65 steel was apparently composed of two stages, 740-765°C and 765-875°C respectively. In order to clarify the microstructure evolution during the two stages, interrupt heat treatment tests were performed and subsequent microstructural observations showed that the first stage (740-765°C) was corresponding to the dissolution of fine carbides particles and the second stage (765-875°C) was corresponding to αγ phase transformation. Firstly, austenite nucleates at interfaces between fine carbide particles and ferrite matrix due to the high interface energy there and then the carbide particles dissolve into the austenite nucleus, which constitutes the first stage. After the fine carbide particles dissolve completely into the austenite nucleus, the ferrite matrix relatively far from the original carbide particles needs higher thermal driving force to transform to austenite, therefore the major αγ transformation occurs at higher temperature range (the second stage).

Abstract: Experimental investigation was conducted on an iron mine in Yunnan, with grade of 35.10% and sulfur content of 1.19%. Through the analysis of ore properties, comparison of single magnetic separation and magnetic-flotation two different process, finally determined magnetic-flotation separation process, obtained high-quality iron ore concentrate with grade of 66.89% and recovery of 76.55%, and sulfur content of 0.15%, achieving good classification effect.

Abstract: Pre-configured powders were mixed uniformly through bonding granulation method. The boracic iron based self-lubricating composites with copper of different mass were prepared by the powder metallurgy press-sinter process. The tribological properties under different conditions of load were investigated on HDM20 end-face tribometer. The composite structure, the wear mechanism which copper affect the friction and wear behaviors of boracic iron based composites were analyzed by using X-ray diffraction, EDS and metallographic microscope. The results show that elementary copper which forming alloy phase could strengthen the combination of each phase in composites, playing the role of binder, improve the tribological properties. The synergistic effect between the phases combination, hardness and strength of Cu-20w composite were observably, which lead to the excellent tribological properties synthetically.