The surface composition, coordination environment, and chemical state of arsenopyrite dictate the propensity of the mineral to undergo oxidation, leaching, and flotation separation. Because of this, it is of great significance to study the mechanism by which mechanical ball milling affects the composition and coordination of the surface atoms. In this study, the arsenopyrite powder was ground using ball milling under argon. Then, the composition and oxidation state of the Fe, As, and S atoms on the arsenopyrite surface were characterized by XPS after different ball milling durations. A surface reconstruction model was constructed using density functional theory (DFT) calculations by adsorption of single atoms and multiple atoms onto the (001) surface of arsenopyrite, and the atomic configuration, binding energy, and formation energy of the reconstructed surface were calculated. The results showed that the relative content of Fe atoms raised from 30.3 % to 36.3 % as the duration of ball milling increased from 0 to 2 h, while the relative content of S atoms reduced from 33.33 % to 28.47 % under the same conditions. Furthermore, as the duration of ball milling was extended, there was an enhancement in the oxidation state of the atoms on the surface. In particular, S atoms under prolonged ball milling were converted to S0 (S monomer polymer). The binding energy between S atoms and the ideal surface was significantly greater than the energies between Fe and As atoms and the surface. Furthermore, the binding energy between the reconstruction layer and the ideal surface was positively correlated with the ratio of Fe atoms, with the 1Fe + 3As + 2S structure having the lowest binding energy and the 3Fe + 1As + 2S and 3Fe + 2As + 1S structures having the highest binding energies. When the surface was rich in S atoms, the formation energy of the reconstructed surface was the most negative, indicating the highest surface stability.

中文翻译：

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阐明球磨对砷黄铁矿表面重建的机理：XPS 性能与理论研究


砷黄铁矿的表面组成、配位环境和化学状态决定了矿物发生氧化、浸出和浮选分离的倾向。正因为如此，研究机械球磨影响表面原子组成和配位的机制具有重要意义。在本研究中，砷黄铁矿粉末在氩下使用球磨研磨。然后，采用XPS对不同球磨持续时间后砷黄铁矿表面Fe、As和S原子的组成和氧化态进行了表征。利用密度泛函理论 （DFT） 计算，将单个原子和多个原子吸附到砷黄铁矿 （001） 表面，构建表面重建模型，计算重建表面的原子构型、结合能和形成能。结果表明，在相同条件下，随着球磨持续时间从 0 到 2 h，Fe 原子的相对含量从 30.3 % 提高到 36.3 %，而 S 原子的相对含量从 33.33 % 降低到 28.47 %。此外，随着球磨持续时间的延长，表面原子的氧化态增强。特别是，在长时间球磨下，S 原子转化为 S0（S 单体聚合物）。S 原子与理想表面之间的结合能明显大于 Fe 和 As 原子与表面之间的能量。此外，重建层与理想表面之间的结合能与 Fe 原子的比例呈正相关，其中 1Fe + 3As + 2S 结构的结合能最低，而 3Fe + 1As + 2S 和 3Fe + 2As + 1S 结构的结合能最高。 当表面富含 S 原子时，重构表面的形成能最负，表明表面稳定性最高。