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首页> 外文期刊>Materials science & engineering >Synthesis and properties of ternary (K, NH_4, H_3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions
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Synthesis and properties of ternary (K, NH_4, H_3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

机译：在模拟生物浸出溶液中从铁氧化酸性硫杆菌培养物中沉淀出的三元（K，NH_4，H_3O）-亚铁酸盐的合成及性能

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The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2-4.4 and ambient temperature in media containing mixtures of K~+ (0,1,4,6,12,31 mM) and NH_4~+ (6.1, 80,160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO_4 solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 ℃ As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe_3(SO_4)_2(OH)_6) and/or schwertmannite (idealized formula Fe_8O_8(OH)_6(SO_4) ·nH_2O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K~+ (≤4 mM) and NH_4~+ (≤80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K~+ and NH_4~+ are similar, K~+ greatly facilitated the formation of a jarosite phase compared to NHt. Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH_4, H_3O)-solid solutions that were also deficient in structural Fe, especially at low NH_4 contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K~+ and NH_4~+ in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH_4-jarosite were detected in the un-aged precipitates.
机译：这项研究的目的是在含有K〜+（0,1、4、6、12、31 mM）混合物的介质中，通过在环境温度和pH 2.2-4.4的条件下对亚铁进行生物氧化，合成一系列固溶的钾长石。和NH_4〜+（6.1，80,160，320 mM）。起始原料是用于铁氧化酸硫杆菌的液体培养基，其由120 mM FeSO_4溶液和pH 2.2的无机盐组成。接种过氧化亚铁后，将培养物在摇瓶中于22℃孵育。细菌氧化亚铁时，三价铁水解并沉淀为黄铁矿类矿物（AFe_3（SO_4）_2（OH）_6）和/或schwertmannite（理想化）式Fe_8O_8（OH）_6（SO_4）·nH_2O）。通过X射线衍射（XRD），元素分析和Munsell颜色对沉淀物进行表征。在介质中，K〜+（≤4mM）和NH_4〜+（≤80mM）的低含量组合下，Schwertmannite是主要的矿物产品。在较高的单一浓度或组合浓度下，会产生淡黄色的黄钾铁矾相，Munsell色相提供了一种检测氧化产物中少量schwertmannite的灵敏手段。尽管K〜+和NH_4〜+的水合离子半径相似，但与NHt相比，K〜+大大促进了黄钾铁矾相的形成。通过细化粉末XRD图谱计算的晶胞和晶胞体积表明，产生的黄钾铁矾相主要是三元（K，NH_4，H_3O）固溶体，它们也缺乏结构铁，尤其是在NH_4含量低时。因此，从模拟的生物浸出系统中沉淀出三价铁，生成黄铁矿固溶体，其化学组成取决于合成介质中K〜+和NH_4〜+的相对浓度。在未老化的沉淀物中未检测到涉及离散的端基K-黄铁矿或NH_4-黄铁矿的相分离。

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