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首页> 外文期刊>Crystal growth & design >Dissolution-Recrystallization of (Mg,Fe)CO3 during Hydrothermal Cycles: Fe-II/Fe-III Conundrums in the Carbonation of Ferromagnesian Minerals
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Dissolution-Recrystallization of (Mg,Fe)CO3 during Hydrothermal Cycles: Fe-II/Fe-III Conundrums in the Carbonation of Ferromagnesian Minerals

机译：在水热循环期间（Mg，Fe）Co3的溶解 - 重结晶：铁磁性矿物碳化的Fe-II / Fe-III难题

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摘要

Crystallization experiments were performed at high supersaturation to obtain metastable (Mg,Fe)CO3 precipitates and study their evolution during hydrothermal heating in a nitrogen atmosphere. The primary (Mg,Fe)CO3 solids undergo a dissolution-recrystallization process driven by two forces: the preferential partition of Fe2+ toward the (Mg,Fe)CO3 solid solution and the oxidation of aqueous Fe2+ species to form Fe(III)-bearing solids. Under limited oxygen supply, the oxidation of Fe2+ is a slow process, particularly in the presence of chlorine and inorganic carbon. In absence of oxidation, the initial solid solution should become increasingly Fe-rich as the supersaturation decreases and the system approaches equilibrium. Here, the secondary (Mg,Fe)CO3 solids become the wrong way round, Mg-rich. The gradual oxidation of the aqueous Fe2+ species eventually leads to precipitation of magnetite, which is also metastable because the aqueous solution is maximally supersaturated with respect to hematite. In most computer implementations, the aqueous activities of Fe2+ and Fe3+ are adjusted to redox equilibrium, and the supersaturation with respect to Fe-bearing solids is determined from these activities. Unfortunately, this approach does not provide supersaturation values in real time. Reactions between aqueous species are actually not instantaneous and can be slower than the dissolution/precipitation of related solids. Considering this fact is essential in modeling the artificial carbonation of ferromagnesian minerals for CO2 sequestration purposes.
机译：结晶实验在高过饱和度下进行，得到稳定（Mg，Fe）Co3沉淀并研究其在氮气氛中的水热加热过程中的进化。主要（Mg，Fe）CO 3固体经历由两个力驱动的溶解 - 再结晶过程：Fe2 +朝向（Mg，Fe）CO 3固溶体和水性Fe2 +种类的氧化的优先分配，形成Fe（iii） - bearing固体。在有限的氧气供应下，Fe2 +的氧化是一种缓慢的方法，特别是在存在氯和无机碳中。在没有氧化的情况下，由于过饱和降低并且系统接近平衡，初始固溶溶液应越来越丰富。这里，二次（Mg，Fe）CO3固体变成错误的方式，富含富含碎片。含水Fe2 +物种的逐渐氧化最终导致磁铁矿的沉淀，这也是稳定的，因为水溶液相对于赤铁矿最大饱和。在大多数计算机实现中，将Fe2 +和Fe3 +的水性活性调节至氧化还原平衡，并且从这些活性确定相对于Fe轴承固体的过饱和度。不幸的是，这种方法没有实时提供超饱和值。水性物质之间的反应实际上不是瞬间的，并且可以比相关固体的溶解/沉淀慢。考虑到这一事实对于模拟铁磁性矿物的人工碳酸化以进行二氧化碳封存目的是必要的。

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  • 来源
    《Crystal growth & design》 |2017年第8期|共13页
  • 作者

    Di Lorenzo Fulvio; Prieto Manuel;

  • 作者单位

    Univ Oviedo Dept Geol C Jesus Arias de Velasco S-N E-33005 Oviedo Spain;

    Univ Oviedo Dept Geol C Jesus Arias de Velasco S-N E-33005 Oviedo Spain;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 晶体学;
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