Alternatives for arsenic storage in waste forms - Thermodynamics of selected Fe,Al arsenates

以废物形式储存砷的替代方案 - 选定的砷酸铁、铝的热力学

• 批准号: 299245417
• 负责人: Professor Dr. Juraj Majzlan, Ph.D.
• 金额: --
• 依托单位: Lehrstuhl Allgemeine und Angewandte Mineralogie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/299245417?language=en
• 关键词: Alternatives; arsenic; storage; waste; forms

Arsenic is a metalloid of environmental concern, toxic to all living organisms. A substantial portion thereof enters the environment commonly by mining and beneficiation of the ores. Here, I propose to investigate the thermodynamic properties of Fe,Al arsenates which seem to be promising alternatives for the storage of arsenic at polluted sites. Pharmacosiderite, (K,Na,Ba0.5)Fe4(AsO4)3(OH)4·5H2O, was identified by our work and by work of others as a mineral commonly occurring in mature, naturally polluted soil profiles. In contrast to scorodite, FeAsO4·2H2O, currently the best choice for arsenic immobilization, pharmacosiderite appears to be stable also under mildly acidic to circumneutral conditions. The ferric orthoarsenate, FeAsO4·0.75H2O, is a high-temperature (~200 ºC) phase, forming in high-pressure oxidation of arsenopyrite-pyrite ores. It is therefore present, albeit in small amounts, in waste forms from this type of technology. It should be investigated how soluble this phase is; if it should perform better than the other arsenic-containing phases, the technologies could be adjusted to favor the production of this phase. The scorodite-mansfieldite (AlAsO4·2H2O) solid solution may be another promising candidate by the virtue of decreasing Gibbs free energy (hence, decreasing solubility) of the solid-solution members by Fe-Al mixing. The proposed work will be done by a combination of calorimetric techniques on synthetic samples, characterized extensively by powder X-ray diffraction, scanning electron microscopy, and electron microprobe. For the mansfieldite sample, its purity will be checked additionally by nuclear magnetic resonance (NMR) spectroscopy. The project will conclude by a calculation of a series of phase diagrams for ambient and high-temperature (up to 300 ºC) conditions, to display and compare the solubility and stability of Fe-Al arsenates and sulfoarsenates.

砷是一种引起环境问题的准金属，对所有生物体都有毒，其中很大一部分通常通过矿石的开采和选矿进入环境。我们的工作和工作确定了在污染场地储存砷的替代方案，(K,Na,Ba0.5)Fe4(AsO4)3(OH)4·5H2O。与目前砷固定的最佳选择——臭葱石 FeAsO4·2H2O 相比，药菱铁矿在弱酸性至中性条件下也很稳定。 ·0.75H2O，是一种高温（~200 ℃）相，在高压下形成因此，砷黄铁矿-黄铁矿矿石中的砷含量很少，因此应研究该相的溶解度是否优于其他含砷相。可以调整技术以有利于该相的生产，由于减少了吉布斯自由能，臭葱石-锰辉石（AlAsO4·2H2O）固溶体可能是另一个有前途的候选者。通过 Fe-Al 混合来降低固溶体成员的溶解度（因此，降低溶解度）拟议的工作将通过结合合成样品的量热技术来完成，其特征在于粉末 X 射线衍射、扫描电子显微镜和电子微探针。锰辉石样品的纯度将通过核磁共振 (NMR) 光谱进行额外检查。该项目将通过计算一系列环境温度和高温（最高温度）的相图来得出结论。 300 ℃）条件下，显示并比较铁铝砷酸盐和磺基砷酸盐的溶解度和稳定性。

项目成果

Thermodynamic properties of mansfieldite (AlAsO4·2H2O), angelellite (Fe4(AsO4)2O3) and kamarizaite (Fe3(AsO4)2(OH)3·3H2O)

• DOI: 10.1180/mgm.2018.107
• 发表时间: 2018-05
• 期刊: Mineralogical Magazine
• 影响因子: 2.7
• 作者: J. Majzlan;U. Nielsen;E. Dachs;A. Benisek;P. Drahota;U. Kolitsch;J. Herrmann;Ralph M. Bolanz;M. Števko

Thermodynamic properties of FeAsO4·0.75H2O - a more favorable disposable product of low As solubility

• DOI: 10.1016/j.hydromet.2016.05.019
• 发表时间: 2016-09
• 期刊: Hydrometallurgy
• 影响因子: 4.7
• 作者: J. Majzlan;E. Dachs;A. Benisek;P. Drahota