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1

Influence of fenugreek-gum and particle size on performance of talc flotation

Gu G., Mo C., Zhao K., Chen Z., Wang X.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

1026--1033

EN

Talc usually exists as a gangue mineral in copper-nickel sulfide, molybdenite etc. In order to separate precious metals, naturally hydrophobic talc should be depressed effectively in flotation process. The effect of fenugreek-gum (FG) on the flotation performance of talc with different particle sizes was studied. The depression mechanism was investigated extensively through tests of flotation, adsorption and zeta potential, as well as infrared spectroscopy and laser particle size analysis. Flotation results indicated that the FG had a strong depression ability for talc with the particle size of -0.074 + 0.037 mm, -0.037 mm and -0.010 mm when proper dosage of FG was added. The coarse talc was completely depressed by 2.5 mg/ dm3 FG. When the particle size decreased, more FG was required to obtain the maximum depressing effect, which was verified by adsorption tests. FG reduced the electronegativity on the talc surface by chemical adsorption, and flocculation of talc powders caused a high efficient depressing effect.

2

Dispersive effect of low molecular weight sodium polyacrylate on pyrite-serpentine flotation system

Zhao K., Yan W., Wang X., Gu G., Deng J., Zhou X., Hui B.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1200--1213

EN

In this work, the dispersive effect of low molecular weight sodium polyacrylate (PAAS) on serpentine, and its dispersion mechanism were systematically investigated through zeta potential measurements, micro and batch flotation as well as adsorption tests. At pH 5, where flotation of iron sulphide was routinely performed, pyrite and serpentine minerals were oppositely charged, and therefore they were attracted to each other. Slime coatings of serpentine adhered to the surface of pyrite, decreasing the adsorption density of a collector on the pyrite surface, but also reducing the flotation recovery. PAAS increased the flotation recovery of pyrite by promoting dispersion between pyrite and serpentine. The effective flotation separation of pyrite from the refractory iron sulphide ore was possible by using PAAS as a dispersant. Anionic PAAS adjusted the surface potential of serpentine through adsorption on the serpentine surface and changed the interaction between pyrite and serpentine particles from attractive to repulsive, and then dispersed pyrite and serpentine.

3

Changes in the states of polarization of random electromagnetic beams in atmospheric turbulence

Li J., Zhao K., Lai Y.

Optica Applicata

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2017

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Vol. 47, nr 1

51--62

EN

Taking the random electromagnetic cosh-Gaussian beam as a typical example of random electromagnetic beams, the analytical expressions for the cross-spectral density matrix element of random electromagnetic cosh-Gaussian beams propagating through non-Kolmogorov atmospheric turbulence are derived, and used to study the changes in the states of polarization (degree of polarization, orientation angle and degree of ellipticity) of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence. It is shown that the states of polarization of random electromagnetic cosh-Gaussian beams in non-Kolmogorov atmospheric turbulence are different from those in free space. The degree of polarization decreases, and the orientation angle and degree of ellipticity increase with increasing structure constant. The on-axis degree of polarization and the degree of ellipticity appear to have an oscillatory behavior and the orientation angle has a rapid transition for the larger cosh-part parameter of random electromagnetic cosh-Gaussian beams in atmospheric turbulence.

4

Study on Underwater Explosive Welding of Al-Steel Coaxial Pipes

Yu Y., Ma H., Zhao K., Shen Z., Cheng Y.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

251--265

EN

In order to solve the aluminum surface ablation issue of Al-Steel bimetallic pipes manufactured by the explosive welding technique, a novel explosive welding system has been designed to weld Al-Steel coaxial pipes. The stand-off distance was chosen according to an empirical formula. A special Explosive Cord with an aluminum coating was used as the explosive. Four experiments were performed using Explosive Cords 1, 2, 3 and 4, respectively. In each experiment, three reliable PVDF (Polyvinylidene Fluoride) piezoelectric film sensors were used to sample the impact pressure between the parent pipe and the flyer pipe along the detonation direction. p-t Curves were obtained at different points on the bimetallic pipe manufactured by Explosive Cord 1. In order to observe the inner surface and to judge the bonding interface, specimens were cut along the axial direction. BSE (Backscattering Electron) images of the interfaces were obtained. According to these pictures from all of the specimens cut along the axial direction, the surface ablation phenomenon has disappeared. The bimetallic pipe manufactured by the new welding system using Explosive Cord 3 has an irregular wavy interface, between micro and small wavy interface, which is one of the best bonding forms.

5

A new approach for simultaneous shape and topology optimization based on dynamic implicit surface function

Guo H., Zhao K., Wang M. Y.

Control and Cybernetics

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2005

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Vol. 34, no 1

255-282

EN

In the present paper, a new approach for structural topology optimization based on dynamic implicit surface function (DISF) is proposed. DISF is used to describe the shape/topology of a structure, which is approximated in terms of the nodal values. Then, a relationship is established between the element stiffness and the values of the implicit surface function on its four nodes. In this way and with some non-local treatments of the design sensitivities, not only the shape derivative but also the topological derivative of the optimal design can be incorporated in the numerical algorithm in a unified way. Numerical experiments demonstrate that by employing this approach, the computational efforts associated with DISF (and level set) based algorithms can be diminished. Clear optimal topologies and smooth structural boundaries free from any sign of numerical instability can be obtained simultaneously and efficiently.