Abstract In this study, the impact of pyrite and pyrrhotite on the arsenic solution species in arsenopyrite pressure leaching were investigated by in-situ synchrotron X-Ray Absorption Spectroscopy (XAS). At an oxygen pressure of 28 bar and room temperature, the solution As existed as As(V) (0.5 M H2SO4 coexisting with arsenopyrite (Aspy), arsenopyrite/pyrite or arsenopyrite/pyrrhotite). At higher temperatures, the As(III) appeared and contributed to an increasing portion of the As species with the increase of temperature, which was re-oxidised to As(V) in the cooling stage. The addition of pyrrhotite (Po) facilitated the reduction of As(V) and stabilised As(III) in the solution. On the other hand, the addition pyrite in the leaching system favoured the presence of As(V) in the solution. This result could be explained by the catalysing effect of pyrite on As oxidation. The S k-edge XANES showed significant surface oxidation happened in arsenopyrite/pyrrhotite system but not in the other two systems, which further proved the high stability of As(III) in Aspy/Po system was because of the high reactivity of pyrrhotite that created a more reductive environment in the solution.

中文翻译：

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黄铁矿/磁黄铁矿对毒砂压力浸出中含水砷种类的影响：XAS 研究

摘要 本研究采用原位同步辐射X射线吸收光谱法(XAS)研究了黄铁矿和磁黄铁矿对毒砂加压浸出过程中砷溶液种类的影响。在 28 巴的氧气压力和室温下，溶液 As 以 As(V) 形式存在（0.5 M H2SO4 与毒砂 (Aspy)、毒砂/黄铁矿或毒砂/磁黄铁矿共存）。在更高的温度下，As(III) 出现并随着温度的升高导致 As 物种的增加，在冷却阶段被重新氧化为 As(V)。磁黄铁矿 (Po) 的加入促进了溶液中 As(V) 的还原和稳定的 As(III)。另一方面，浸出系统中添加的黄铁矿有利于溶液中 As(V) 的存在。这一结果可以通过黄铁矿对砷氧化的催化作用来解释。S k-edge XANES 显示毒砂/磁黄铁矿系统发生了显着的表面氧化，而其他两个系统没有发生，这进一步证明 As(III) 在 Aspy/Po 系统中的高稳定性是因为磁黄铁矿的高反应性产生了解决方案中更具还原性的环境。