In this study, the surface modification of arsenopyrite and pyrite with low temperature oxygen plasma was developed as an effective approach to improve the flotation separation efficiency of minerals. The micro-flotation experiments results indicated that plasma pre-treatment can achieve selective flotation of arsenopyrite from pyrite. The XPS analysis results indicated that the oxidation degree of plasma-modification arsenopyrite surface is much higher than that of pyrite. A large number of sulfide components on the surface of the mineral were oxidized to highly-valence hydrophilic oxides by plasma pre-treatment. ICP-MS analysis results revealed that the dissolution rate was determined by the oxidation degree of minerals and plasma modified accelerated the dissolution of arsenopyrite and pyrite. Zeta potential determination results confirmed that plasma can keep a relatively higher adsorption of SBX on the pyrite surface but inhibit the adsorption of collector onto the arsenopyrite surface.

The flotation enrichment of fine-particle wolframite played a crucial role in production of strategic key metal tungsten. In this paper, N-[(3-hydroxyamino)-propoxy]-N-hexyl dithiocarbamate (HAHD) was designed to strengthen the flotation recovery of wolframite. The in situ AFM images clearly exhibited that the pre-activation of wolframite with Pb²⁺ ions significantly enhanced the self-assemble and aggregation of HAHD on its surface, and its surface hydrophobicity and floatability dramatically improved. The FTIR and XPS results recommended a chemisorption of HAHD to the Pb(II)-activated wolframite, and in the surface HAHD-Pb(II) complexes, both dithiocarbamate and hydroxamate groups chelated Pb(II) to deliver the four-membered and five-membered ring configurations. The double-site adsorption rendered a closed loop anchor of HAHD on the Pb(II)-activated wolframite surface, which essentially weakened the hydration of OH- ions toward Pb²⁺, Fe²⁺ or Mn²⁺ ions in/on wolframite interface. In addition, the hexyl group exhibits a strong hydrophobization, and the dithiocarbamate displays a selective affinity against alkaline earth metal minerals. These encouraged HAHD to be a strong-power and selective collector for wolframite versus calcite at its low dose.

The high reactivity of the acetylene group enables the formation of strong chemical bonds with active sites on mineral surfaces, thereby improving the flotation performance of gold minerals. This study utilized density functional theory (DFT) to analyze the quantum chemical parameters of structure, Mulliken population, and the frontier orbitals of a thioester collector containing an acetylene group, PDEC (prop-2-yn-1-yl diethylcarbamodithioate). PDEC was compared with analogous thioester collectors Z-200 and Al-DECDT. The interaction mechanism of PDEC on the Au(1 1 1) surface was simulated, followed by empirical validation through adsorption experiments. The findings indicate that the S atom of PDEC in the carbon–sulfur group exhibits shorter covalent bond lengths, and has reduced carbon–sulfur double bonds and Mulliken population, resulting in enhanced electron localization. This confers greater selectivity to PDEC during its adsorption on mineral surfaces. Frontier orbital analysis shows that the electrons of the acetylene group possess a notable electron-accepting capacity, significantly influencing the frontier orbital energy of PDEC and playing a pivotal role in the bonding interaction with mineral surfaces. Both the S atom in the carbon–sulfur group and its acetylene group establish stable adsorption structures with the A(111) surface in a single coordination mode. The adsorption energy sequence is PDEC > Al-DECDT > Z-200. Partial density of states demonstrates that the S 3p orbit of the carbon–sulfur group hybridizes with the Au 5d orbit, while the C 2p orbit of the acetylene group engages in weaker back-donation bonding with the Au 5d orbit. This is corroborated by the electron density difference and post-adsorption Mulliken population analyses, revealing that the S atom of the carbon–sulfur group in PDEC donates electrons to the Au atom, forming dominant positive coordination bonds, whereas the acetylene group accepts partial electrons from the Au atom, resulting in weaker back-donation bonds. The adsorption experiments align with the DFT adsorption energy results.

The high reactivity of acetylene group the formation of strong chemical bonds with active sites on mineral surfaces, thereby improving the flotation performance of gold minerals. This study utilized Density Functional Theory (DFT) to analyse the quantum chemical parameters of structure, Mulliken population, and the frontier orbitals of a thioester collector containing an acetylene group, PDEC (prop-2-yn-1-yl diethylcarbamodithioate). PDEC is compared with analogous thioester collectors Z-200 and Al-DECDT, and the interaction mechanism of PDEC on the Au(1 1 1) surface is simulated, followed by empirical validation through adsorption experiments. The findings indicate that S atom of PDEC in the carbon-sulfur group exhibit shorter covalent bond lengths, and reduced carbon-sulfur double bonds and Mulliken population, resulting in enhanced electron localization. This confers greater selectivity to PDEC during its adsorption on mineral surfaces. Frontier orbital analysis shows that the electrons of acetylene group possess a notable electron-accepting capacity, significantly influencing frontier orbital energy of PDEC and playing a pivotal role in the bonding interaction with mineral surfaces. Both the S atom in carbon-sulfur group and its acetylene group establish stable adsorption structures with the A(111) surface in a single coordination mode. The adsorption energy sequence is PDEC > Al-DECDT > Z-200. Partial density of states demonstrates that S 3p orbit of carbon-sulfur group hybridize with Au 5d orbit, while the C 2p orbit of the acetylene group engage in weaker back-donation bonding with Au 5d orbit. This is corroborated by electron density difference and post-adsorption Mulliken population analyses, revealing that S atom of carbon-sulfur group in PDEC donate electrons to Au atom, forming dominant positive coordination bonds, whereas the acetylene group accepts partial electrons from Au atom, resulting in weaker back-donation bonds. The adsorption experiments align with the DFT adsorption energy results.