白烟灰的物相分析及酸浸脱砷工艺

白烟灰因其含有砷等有毒化合物,其安全堆存是冶金企业面临的难题。 对白烟灰进行物相分析是处理该烟灰,使其达到环保要求堆存的重要依据。 采用X射线光电子能谱(XPS)和X射线粉末衍射(XRD)研究了河南某企业白烟灰的物相组成及化学结合状态,确定其所含化学成分及元素含量。 结果表明,样品中元素As相对含量高达20.99%,其中11%以游离态As₂O₃形式存在,其余以PbAs₂O₆形式存在。 样品中还含有少量的Cu、Pb、Zn等金属及其氧化物。 根据被测样品物相组成,提出了一种氧化酸浸脱砷的方法,并确定了最佳脱砷工艺,在最佳工艺条件下,砷的浸出率高达97.1%,高于文献报道的砷的浸出率。

Determination of Speciation in White Ash and Acid Leaching Arsenic Removal Technique

White ash safety storage is a serious problem because it contains toxic arsenic compounds. The phase analysis of white ash will provide some important information for how to handle these ashes and make it satisfy environment requirement. X-ray photoelectron spectroscopy(XPS) provides information on the chemical state of elements in bulk samples and single minerals, as well as the qualitative and quantitative determination of the surface or reaction layers(less than 10 nm thick) of minerals and grains. In this paper, to determine the chemical states and content of various elements, the phase composition and chemical states in white ash of an enterprise in He'nan province were studied by XPS and X-ray diffraction(XRD). The results indicate that the relative content of As runs up to 20.99%, in which 11% is As(Ⅲ), and the rest is As(Ⅴ). In addition, the sample contains small amounts of Cu, Pb, Zn and their oxides. Based on the composition of the sample, a novel acid leaching method by hydrogen peroxide selective oxidation was proposed for removing arsenic. The method can make As(Ⅲ) convert to As(Ⅴ) with low toxicity and improve arsenic leaching ratio. The ratio can runs up to 97.1% in the best leaching process.