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Influence of hydrated Ca2+ and Mg2+ complexes on the sulfidization of smithsonite : density functional based tight binding (DFTB+) study

Wu Zhiqiang, Tang Xiaoqin, Chen Jianhua, Chen Ye

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 6

art. no. 156040

Ca2+ and Mg2+ are the most dominating unavoidable ions in the smithsonite flotation. In this paper, the effect of Ca2+ (Mg2+) on the surface of smithsonite sulfidization in a system where water molecules are present was investigated using density functional based tight binding (DFTB+) simulations for the first time. The results indicated that the adsorption of hydrated Ca2+ complexes is stronger than that of hydrated Mg2+ complexes on the hydrated smithsonite (101) surface. In addition, at low concentrations of sodium sulfide, there is no adsorption of HS- on the surface pre-adsorbed with hydrated Ca2+ complexes, but only on the surface pre-adsorbed with hydrated Mg2+ complexes. At high concentrations of Na2S, S2- weakens the adsorption of hydrated Ca2+ complexes due to competitive adsorption, but the presence of S2- could desorb hydrated Mg2+ complexes from the surface. The results compared the differences in effects of Ca2+ and Mg2+ on smithsonite sulfidization, which could provide an atomic scale basis for researching the surface sulfidization of oxide minerals.

Stochastic P-bifurcation of a 3-DOF airfoil with structural nonlinearity

Hao Ying, Du Xuewen, Hu Yuda, Wu Zhiqiang

Journal of Theoretical and Applied Mechanics

2021

Vol. 59 nr 2

307--317

In this paper, the stochastic-aeroelastic nonlinear response of a three-degree-of-freedom (3-DOF) structural nonlinear airfoil with a control flap is presented. The critical parameter conditions of stochastic P-bifurcation are solved by using the improved average method, the stochastic average method combined with the singularity theory. The results show that the periodic solution produced by Hopf bifurcation has involved a second bifurcation, the nonlinear critical speed of saddle node bifurcation points is advanced, and the airfoil appears bi-stable. The stochastic singularity analysis shows that the increasing stochastic disturbance intensity will cause a greater probability for a large amplitude stochastic flutter.