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2 Physicochemical Problems of Mineral Processing

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DFT and TOF-SIMS study of the interaction between hydrogen sulfide ion and malachite (–201) surface

Mao Yingbo, Wu Dandan, Huang Lingyun

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 5

71--79

In this paper, the mechanism of interaction between hydrogen sulfide ions and malachite was investigated using density functional theory (DFT) calculations and time of flight secondary ion mass spectrometry (TOF-SIMS). The DFT calculations showed that HS− adsorption on the malachite (−201) surface was stronger than that of S adsorption resulting from the higher number of electron transfers in the solution which accelerated the sulfidation reaction rate. Density of states (DOS) analysis showed that the near Fermi level was jointly contributed to by the Cu 3d, O 2p, O 2S, and S 3P orbits after adsorption of HS− on the malachite (–201)surface. It was found that the 2p orbital of O and the 3p orbital of S overlapped, indicating that S not only reacted with Cu, but also with O. The TOF-SIMS detected S− and CuS2− fragment ion peaks in the 0−150 m/z negative segment of mass spectra. TOF-SIMS also showed that copper sulfide films of certain thicknesses were formed, demonstrating the effectiveness of hydrogen sulfide sulfidation in flotation processes.

Effect of sulfidization on the stability of adsorption of isoamyl xanthate on malachite

Xiong Kun, Wen Shuming, Liu Zilong, Deng Jiushuai, Mao Yingbo

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 3

493--503

The activity and stability of adsorbed isoamyl xanthate (IX) on a malachite surface before and after sulfidization were studied by calculating the malachite dissolved component and adsorption energy and performing experiments pertaining to the zeta potential, adsorption and desorption experiments, and flotation experiments. In the malachite slurry solution, the main components of copper are Cu2+, CuCO3, HCuO2-, CuO2-, and Cu(CO3)22-, and the concentration distribution of these components is related to the slurry pH value. Between pH 5 to 9, the main copper component in the slurry is CuCO3. The malachite surface is negatively charged; however, the sulfur ions or hydrosulfide ions can still adsorb on the surface at a pH of more than 8.2, which indicates that the sulfidization of malachite corresponds to the chemical adsorption, and the surface electrical properties of the malachite are not obvious to the sulfidization. The adsorption activity of malachite on IX is stronger than that of the sulfide malachite; however, the desorption ratio of IX with respect to the malachite is higher than that pertaining to the sulfide malachite. The adsorption energy of IX on the malachite and sulfide malachite surface was -449.6 kJ/mol and -1134.7 kJ/mol, respectively, and the IX adsorbed on the sulfide malachite surface was more stable. The flotation experiments indicated that the sulfidization of malachite reduced the consumption of IX; however, the recovery of malachite was improved.