不同条件下形成的黄钾铁矾微形貌对比研究

黄钾铁矾是酸性矿山废水（AMD） 中常见的次生矿物，能有效吸附AMD中Cu、Pb、Zn、Gd、As等重金属元素。不 同条件下形成的黄钾铁矾微形貌不同，其吸附能力也不同。文章通过化学法和微生物法合成了黄钾铁矾，并在粤北大宝山 矿酸性矿山废水中采集了含黄钾铁矾的泥样。利用扫描电镜-能谱分析（SEM） 和X光衍射（XRD），对三种不同条件下形 成的黄钾铁矾进行鉴定和微形貌特征观察，并分析黄钾铁矾的形成条件。结果表明，常温条件下，pH值2.0~2.5时能够化 学合成黄钾铁矾，其晶体粒径约2~10 μm，且晶形呈板状；而在65℃时，可在pH2.0~3.0之间化学合成黄钾铁矾，但晶形 差。微生物法合成黄钾铁矾pH范围是2.0~5.0，其晶形完好，呈菱面体且晶体大小比较均匀，而约为2~4 μm。酸性矿山废 水中的黄钾铁矾形成的pH值为2.5~3.5，晶形为菱面体形，单个晶体大小多为1~2 μm。根据其形成条件和微形貌特征，文 章推测酸性矿山废水中形成的黄钾铁矾可能是微生物成因。

A Comparative Study on Microtopography of Jarosite Formed in Different Conditions

Jarosite is a very common secondary mineral in acid mine drainage (AMD). It can absorb effectively heavy metallic elements such as Pb, Zn, Gd, As in AMD. The jarosite formed under different conditions is of diverse microtopography and different adsorption capacities to heavy metallic ions. In this paper, jarosite was synthesized by chemical and microbiological methods, respectively, and the samples of sediments with jarosite-bearing secondary minerals were collected form the AMD of Dabaoshan Mine in the north Guangdong Province. The jarosite formed under different conditions was identified by using SEM and XRD, its microtopographic characteristics were observed, and the synthesis conditions of jarosite were investigated. The results show that the range of pH values in which jarosite can be chemically synthesized is approximately 2.0-2.5 at room temperatures. The crystal size of the synthetic jarosite is about 2-10 μm and the crystalline form is plate-like. Jarosite can also be chemically synthesized at 65℃ with a wider range of pH values between 2.0-3.0, but the crystalline form is relatively poor. Jarosite can be synthesized by microbial method in a relatively large range of pH values between 2.0-5.0, which has nearly perfect rhombohedron-shape crystalline form and relatively uniform sizes about 2-4 μm. Jarosite discovered in sediments of AMD occurs in a pH value ranging from 2.5 to 3.5. It is of relatively perfect rhombohedron-shape crystal and the single crystal size is mostly in 1-2 μm. According to the formation conditions and microtopographic characteristics, the jarosite formed in AMD is probably of microbial origin.