Vanadium in phyllosilicate ores: Occurrence, crystal chemistry, and leaching behavior
Vanadium in phyllosilicate ores: Occurrence, crystal chemistry, and leaching behavior
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DOI：
10.1016/j.mineng.2023.108205
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发表时间：
2023-07-03
影响因子：
4.8
通讯作者：
Zanetta，Pierre-Marie
中科院分区：
文献类型：
--
作者：
Drexler，Maxwell;Barton，Isabel;Zanetta，Pierre-Marie
本文研究了层状硅酸盐中钒的纳米赋存状态，并将其与可浸性联系起来。全球钒资源的很大一部分赋存于层状硅酸盐矿石中，如玫瑰铅矿和含钒绿泥石、粘土和云母。在酸浸过程中，这些矿物中钒的回收率通常很低，但由于不清楚的原因，回收率差别很大。对拉萨尔矿(科罗拉多高原)浸出头和尾矿中的钒伊利石、钒绿泥石和钒绿泥石进行的透射电子显微镜观察表明，所观察到的回收率变化与层状硅酸盐晶格中纳米级氧化钒相的插层有关。这些都存在于本研究中的一些钒伊利石中，与不含钒氧化物的钒伊利石相比，它们表现出更高的浸出回收率。在后者和V型绿泥石中，V以晶体取代的形式存在，没有氧化物嵌入。扫描电子显微镜(STEM)的电子能量损失谱(EELS)测量表明，该晶体V是混合价的，在V-绿泥石中平均为3.3，在钒绿泥石中为3.6，在V-伊利石中为3.8。与氧化物插层不同，这种结晶类型的钒对应于可以忽略的浸出回收率，而无论钒的位置、氧化状态或层状硅酸盐的类型。这些结果揭示了几何冶金中一个中心问题的原因，该问题试图根据地质输入对过程结果进行定量预测。这些结果表明，根据纳米级金属赋存因素的不同，看似相同的矿物(在这种情况下是V-伊利石)可以产生截然不同的浸出回收率。在矿场内部或矿场之间，其他矿石矿物中类似的未被认识到的变化，可能解释了它们在浸出行为中臭名昭著的可变性。
This article examines the nanoscale occurrence patterns of vanadium in phyllosilicates and correlates them with amenability to leaching. A large fraction of the global vanadium resource is hosted in phyllosilicate ores such as roscoelite and V-bearing chlorites, clays, and micas. Recovery of V from these minerals in acid leaching is typically low but varies widely for unclear reasons. Transmission electron microscopy (TEM) of V-illites, V-chlorites, and roscoelites in leach heads and tails from the La Sal mine (Colorado Plateau) shows that the observed variability in recoveries correlates with intercalations of nanoscale V oxide phases within the phyllosilicate lattice. These are present in some of the V-illites in this study, which displayed higher leach recovery than V-illites without the V oxides. In the latter, as well as in V-chlorites, the V occurs as crystallographic substitutions without oxide intercalations. Electron energy loss spectroscopy (EELS) measurements in the scanning transmission electron microscope (STEM) show that this crystallographic V is mixed-valence, averaging 3.3 in V-chlorite, 3.6 in roscoelite, and 3.8 in V-illite. Unlike the oxide intercalations, this crystallographic type of V corresponds to negligible leaching recoveries irrespective of V siting, oxidation state, or type of phyllosilicate.These results shed light on the causes of a central problem in geometallurgy, which is attempting quantitative predictions of process outcomes from geological inputs. These results show that what appears to be the same mineral (in this case V-illite) can yield wildly disparate leach recoveries depending on nanoscale metal occurrence factors. Similar under-recognized variation in other ore minerals, within or between sites, may explain much of the notorious variability in their leaching behavior.