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首页> 外文会议>Global Symposium on Recycling, Waste Treatment and Clean Technology; 20040926-29; Madrid(ES) >THE BEHAVIOUR OF CHROMIUM(Ⅲ) DURING POTASSIUM JAROSITE PRECIPITATION
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THE BEHAVIOUR OF CHROMIUM(Ⅲ) DURING POTASSIUM JAROSITE PRECIPITATION

机译：铬铁钾沉淀过程中铬（Ⅲ）的行为

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摘要

Jarosite precipitation is a useful means of stabilizing toxic species, and accordingly, the behaviour of chromium(Ⅲ) during jarosite precipitation was systematically investigated in a series of laboratory experiments. Although Cr(Ⅲ) analogues of jarosite-type compounds could not be precipitated at temperatures ＜ 100℃, several percent Cr(Ⅲ) substitution for Fe(Ⅲ) in potassium jarosite was possible. However, at temperatures ＞ 200℃, the Cr(Ⅲ) analogue of potassium jarosite (KCr_3(SO_4)_2(OH)_6) is readily precipitated. The formation of the Cr(Ⅲ) analogue is promoted by increasing temperatures, retention times and Cr(Ⅲ) concentrations. Increasing acid concentrations reduce the amount of product formed but suppress the precipitation of amorphous phases. Although increasing K_2SO_4 concentrations result in a greater mass of precipitate, the products formed from concentrated K_2SO_4 solutions are contaminated with an amorphous phase. In fact, the overall results suggest that an amorphous phase precipitates rapidly and that the Cr(Ⅲ) analogue of potassium jarosite forms by the recrystallization, or the dissolution-reprecipitation, of the amorphous phase.
机译：黄铁矿沉淀是稳定有毒物质的一种有用手段，因此，在一系列实验室实验中，系统地研究了黄铁矿沉淀过程中铬（Ⅲ）的行为。尽管黄钾铁矾型化合物的Cr（Ⅲ）类似物在＜100℃的温度下不能沉淀，但黄钾铁矾钾中的Fe（Ⅲ）可能有百分之几的Cr（Ⅲ）替代。然而，在＞ 200℃的温度下，黄钾铁矾的Cr（Ⅲ）类似物（KCr_3（SO_4）_2（OH）_6）容易沉淀。 Cr（Ⅲ）类似物的形成通过增加温度，保留时间和Cr（Ⅲ）浓度来促进。酸浓度的增加减少了所形成产物的量，但抑制了非晶相的沉淀。尽管增加的K_2SO_4浓度会导致更大的沉淀量，但由浓缩的K_2SO_4溶液形成的产物却被非晶相污染。实际上，总体结果表明，非晶相迅速沉淀，并且通过非晶相的重结晶或溶解-再沉淀形成了钾黄钾铁矿的Cr（Ⅲ）类似物。

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