The coprecipitation of selenium(IV) (Se) with iron(III) (Fe) is a widely practiced method for the removal of Se from mineral processing effluents, but the effect of gypsum as a major secondary mineral on the iron-selenium coprecipitation process is still of concern. In our work we first investigated the effects of pH, Fe/Se molar ratio and the neutralizing agent on the removal efficiency of Se by iron-selenium coprecipitation method. The developed two-step Fe-Se coprecipitation method (Fe/Se molar ratio of 4) was superior to the one-step Fe-Se coprecipitation method at pH 4 using CaO as base in terms of the stability of the generated Fe-Se coprecipitates. Raman experimental results indicated the iron-selenium coprecipitates had the by-product of calcium selenite. We then investigated the effect of incorporation of Se into gypsum on the coprecipitation process at different pHs. The fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and scanning electron microscopy (SEM) of the calcium-selenium coprecipitates showed that the Se incorporated into the structure of gypsum at pH 8-10. Therefore, this work has important implications for the development of new technologies for efficient Se removal.

中文翻译：

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石膏对铁/钙-硒共沉淀过程中硒固着的影响。

硒（IV）与铁（III）（Fe）的共沉淀是从矿物加工废水中去除Se的一种广泛实践的方法，但是作为主要次生矿物的石膏对铁硒共沉淀过程的影响仍然值得关注。在我们的工作中，我们首先研究了pH，Fe / Se摩尔比和中和剂对铁硒共沉淀法去除Se的影响。就生成的Fe-Se共沉淀物的稳定性而言，已开发的两步Fe-Se共沉淀法（Fe / Se摩尔比为4）优于在pH 4下使用CaO作为碱的一步Fe-Se共沉淀法。 。拉曼实验结果表明，铁-硒共沉淀物是亚硒酸钙的副产物。然后，我们研究了在不同pH下将Se掺入石膏对共沉淀过程的影响。钙硒共沉淀物的傅立叶变换红外光谱（FTIR），X射线衍射（XRD）和扫描电子显微镜（SEM）表明，硒在pH 8-10时掺入石膏结构中。因此，这项工作对开发有效去除硒的新技术具有重要意义。