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Lead species formation on pure hemimorphite surface and its performance for subsequent sulfidization

Liang Guanyu, Zhang Song, Xian Yongjun, Chen Luzheng

Physicochemical Problems of Mineral Processing

2024

Vol. 60, iss. 2

art. no. 187064

Hemimorphite is important-supplementary resource for the commercial zinc production, but it easy loses into tailings due to extreme difficulty for its surface sulfidization. Adding active metal ions after sulfidization have been widely proposed for enhancing hemimorphite floatability, but its desired efficiency in flotation practice has not yet been completely achieved caused by the instability of sulfide layer. Whereas pre-adsorption of active metal ions to modify the hemimorphite surface has strong potential to make up for this shortcoming. Herein, the feasibility and appropriate environment of free Pb2+ for modifying the pure hemimorphite surface was evaluated. Subsequently, the performance of Pb2+ adsorption for enhancing sulfidization stability and floatability of hemimorphite were investigated. The X-ray photoelectron spectroscopy results indicated that the Pb2+ adsorption on hemimorphite surface was achieved through the Pb ions displacement for Zn ions, and it was bond to oxygen-containing groups on hemimorphite surface. Such adsorption was strengthened with the increasing of solution pH, owing to the abundant Pb hydroxyl species precipitated on mineral under alkaline conditions, in term of the results of visual MINTEQ modeling and time-of-flight secondary-ion mass spectrometry. In addition, the X-ray photoelectron spectroscopy results showed dominant Pb hydroxyl species further reacted with sulfur during subsequent sulfidization to generate much more S species than that of without Pb2+ pre-modification. Meanwhile, such sulfide layer composed by Pb2+ on the mineral surface presented much higher stability than Zn-S species, which was verified via adsorption and desorption tests. As a result, the sulfidization and flotation recovery of hemimorphite increased after Pb2+ pre-adsorption.

Enhancement of xanthate adsorption on chrysocolla surface via sodium diethyldithiocarbamate (DDTC) modification

Liu Dan, Wang Daqian, Xian Yongjun, Tian Xiaosong, Wen Shuming

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 6

art. no. 152599

Chrysocolla is a kind of copper oxide mineral which was difficult to float. In this study, Diethyldithiocarbamate (DDTC) was employed to modify the surface of chrysocolla to improve its xanthate adsorption and floatability. Flotation experiments showed that the DDTC exhibited ability to activate rather than acting as a collector for chrysocolla flotation. After DDTC activation, chrysocolla can be effectively recovered by xanthate. The activation mechanism of DDTC was investigated via Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). During the activation, DDTC bonded to the surface copper atoms of chrysocolla, and more Cu(II) species on the mineral surface were reduced to Cu(I) species, which caused the formation of larger amounts of Cu active sites as –N–C(=S)S–Cu(II)– and Cu(I) species. The results of the adsorption tests and zeta potential measurements revealed that the DDTC-modified mineral surface reinforced adsorption of xanthate ions, thereby improving the chrysocolla floatability. Therefore, the Cu ions double interaction of DDTC and xanthate on the chrysocolla surfaces enhanced the strength and stability of the hydrophobic layer, resulting in an enhanced hydrophobization of the chrysocolla for its flotation.