Abstract Mine tailings rich in Mn and an adjacent creek at Kanye, southeast Botswana, have been investigated by total decomposition of solids, X-ray diffraction, EMPA techniques, sequential extraction, and water leaching to understand binding and mobility of Mn and other trace elements. The investigation revealed weathering of tailings close to the surface of the tailings and higher concentrations of Fe compared to Mn. There also are high concentrations of Ba and Pb in the tailings solids. The principal minerals of Mn and Fe are cryptomelane, K(Mn4+, Mn2+)8O16, and hematite, Fe2O3, respectively. Most Mn is bound to less crystalline phases dissolved in the reducible step of sequential extraction, suggesting high potential for release of Mn and related trace elements. The situation is very different for Fe, which is found mostly in the residual (Aqua Regia) insoluble fraction. This is in a good agreement with high concentrations of mobilized Mn and with low concentrations of mobilized iron in the water leaching test. The order of water-leached trace elements is Ba>Zn > As>V > Cu > Co > Pb where trace elements bound in Mn-oxyhydroxides are preferentially mobilized. In particular, As and V may represent a potential risk for the environment during rainy periods when mine tailings are probably flooded, and tailings material is transported by water in an ephemeral creek. Currently, sediments in the creek are contaminated at least to the boundaries of the Kanye settlement and they can be a source of groundwater contamination during the rainy period. Another possible source of contamination is wind transport and settling of dust particles from mine tailings with resulting ingestion when local farming products are consumed.

中文翻译：

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博茨瓦纳东南部坎耶富锰尾矿和邻近小溪中锰和其他微量元素的迁移率

摘要 通过固体全分解、X 射线衍射、EMPA 技术、顺序提取和水浸，研究了博茨瓦纳东南部 Kanye 的富含锰的尾矿和邻近的小溪，以了解锰和其他微量元素的结合和迁移。 . 调查显示，靠近尾矿表面的尾矿风化，并且与锰相比，铁的浓度更高。尾矿固体中也有高浓度的 Ba 和 Pb。Mn 和 Fe 的主要矿物分别是钾锰矿 K(Mn4+, Mn2+)8O16 和赤铁矿 Fe2O3。大多数 Mn 与在连续提取的可还原步骤中溶解的较少结晶相结合，表明 Mn 和相关微量元素的释放潜力很大。Fe的情况非常不同，它主要存在于残留（王水）不溶性部分中。在水浸出试验中，这与高浓度的流动锰和低浓度的流动铁非常吻合。水浸出的微量元素的顺序是 Ba>Zn>As>V>Cu>Co>Pb，其中结合在 Mn-羟基氧化物中的微量元素优先移动。尤其是在雨季，当尾矿可能被淹没，尾矿材料在一条短暂的小溪中通过水运输时，As 和 V 可能代表对环境的潜在风险。目前，小溪中的沉积物至少在 Kanye 定居点的边界受到污染，在雨季它们可能成为地下水污染的来源。