Galvanic Microencapsulation (GME) Using Zero-Valent Aluminum and Zero-Valent Iron to Suppress Pyrite Oxidation
Galvanic Microencapsulation (GME) Using Zero-Valent Aluminum and Zero-Valent Iron to Suppress Pyrite Oxidation
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DOI：
10.2320/matertrans.m-m2018851
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发表时间：
2019-02
影响因子：
1.2
通讯作者：
S. Seng;C. Tabelin;Motoya Kojima;N. Hiroyoshi;M. Ito
中科院分区：
文献类型：
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作者：
S. Seng;C. Tabelin;Motoya Kojima;N. Hiroyoshi;M. Ito
黄铁矿是矿山废弃物中常见的脉石矿物，其氧化是矿山酸性水形成的主要原因，是世界范围内遇到的一个非常严重的环境问题。为了解决这一问题，我们开发了一种抑制黄铁矿氧化的新技术，称为电微胶囊化（GME）。当两种具有不同静止电位的导电或半导电材料相互作用时，就会发生电相互作用。静止电位较低的材料成为阳极并被氧化，而另一种静止电位较高的材料成为阴极并受到电保护。研究了零价铝（ZVAl）和零价铁（ZVI）用量、浸出时间和pH对黄铁矿氧化的影响。此外，通过电化学测量和表面敏感表征技术研究了GME过程中涉及的抑制机制。结果表明，ZVAl和ZVI的存在抑制了黄铁矿的氧化。随着时间的推移，前3天黄铁矿与ZVAl之间的电相互作用可以忽略不计，这可能是由于ZVAl表面有氧化铝涂层。7 d后，ZVAl对黄铁矿氧化表现出明显的抑制作用。相比之下，ZVI对黄铁矿氧化的抑制作用仅在1天后观察到。循环伏安法和计时安培法表明，ZVAl和ZVI的抑制作用主要是由电相互作用引起的。虽然ZVAl和ZVI可以限制黄铁矿的氧化，但它们的抑制作用只是暂时的，因为黄铁矿表面没有被非反应性涂层钝化。为了诱导涂层形成，延长对硫铁矿氧化的抑制，在ZVI中加入磷酸盐。这些实验只选择了ZVI，因为可能形成磷酸铁，即使在酸性条件下也是非常稳定的材料。在磷酸盐存在的情况下，由于电相互作用和镀层形成的共同作用，ZVI对黄铁矿氧化的抑制作用显著提高。[doi:10.2320 / matertrans.]M-M2018851]
Pyrite is a common gangue mineral in mine wastes, and its oxidation is the primary cause of acid mine drainage (AMD) formation, which is a very serious environmental problem encountered worldwide. To address this problem, we developed a new technique to suppress pyrite oxidation called galvanic microencapsulation (GME). Galvanic interaction occurs when two conductive or semi-conductive materials with di ff erent rest potentials interact with one another. The material with a lower rest potential becomes the anode and is oxidized while the other one with the higher rest potential becomes the cathode and is galvanically protected. In this study, the e ff ects on pyrite oxidation of zero-valent aluminum (ZVAl) or zero-valent iron (ZVI) dosages, leaching time, and pH were elucidated. In addition, the suppression mechanisms involved during GME were investigated by electrochemical measurements and surface-sensitive characterization techniques. The results showed that pyrite oxidation was suppressed in the presence of ZVAl or ZVI. With time, galvanic interaction between pyrite and ZVAl in the fi rst 3 days was negligible, which could be attributed to the Al-oxyhydroxide coating on ZVAl. After 7 days, however, ZVAl exhibited substantial suppressive e ff ects on pyrite oxidation. In comparison, the suppressive e ff ects of ZVI on pyrite oxidation were observed after just 1 day. Cyclic voltammetry and chronoamperometry measurements showed that the suppressive e ff ects of ZVAl and ZVI were predominantly due to galvanic interactions. Although ZVAl and ZVI could limit pyrite oxidation, their suppressive e ff ects were only temporary because the surface of pyrite was not passivated by an unreactive coating. To induce coating formation and prolong the suppression of pyrite oxidation, phosphate was added together with ZVI. Only ZVI was selected for these experiments because of the potential formation of iron phosphate, a very stable material even under acidic conditions. In the presence of phosphate, suppression of pyrite oxidation by ZVI was dramatically improved because of the combined e ff ects of galvanic interactions and coating formation. [doi:10.2320 / matertrans.M-M2018851]