Abstract The idea that there is a consensus in the field of hydrometallurgy that chalcopyrite leaching is hindered by a passivation layer is challenged in this review. Not all studies of chalcopyrite leaching propose that surface layers are passivating. Some claim that there are passivating and non-passivating surface species, but with directly opposing opinions as to which plays the passivating role. The more common passivation proposals are variants of a metal-deficient sulfide or a metal-deficient polysulfide. Sometimes it is claimed these are distinctly different species with different passivating capabilities, at other times they are simply different names for the same thing. These are not well defined and are usually given a general name such as Cu1–xFe1−yS2 or CuFe1-xS2, which is often inferred from electrochemistry and dissolution stoichiometry. In contrast to leaching in acidic solutions, it has been shown that in alkaline solutions with a complexing agent there is no passivating effect. This is despite the same supposedly passivating species being present on the surface as is found in acid solutions. An alternative explanation to the various passivation proposals is that the electronic structure of chalcopyrite dictates the effects observed in electrochemistry and leaching. Natural chalcopyrite has the electronic structure of an n-type semiconductor. As such it is not expected to conduct significant current at modest anodic potentials until a ‘breakdown’ potential is reached. This semiconducting property is often observed in electrochemistry where very low currents are observed under an applied potential up to about 1.0 V (vs SHE), where a rapid increase in current is observed. Other observations such as photocurrents, trends in capacitance and limiting currents have also been attributed to the semiconducting nature of chalcopyrite. This approach has however attracted extremely strong criticism. These critics instead propose that chalcopyrite should be regarded as “pseudo-metallic” rather than semiconducting due to expected metal impurities in a natural sample. Any semiconducting effects observed are said to be due to improper operation of laboratory equipment or are experimental artefacts. However, a careful analysis of the claims of these critics shows that they are mostly speculative – indeed, several are based on incomplete data and misinterpretations of other published work. More objective experimental studies are needed both to verify these criticisms and to prove that surface layers are indeed passivating.

中文翻译：

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对黄铜矿浸出钝化和半导体机制的批判性回顾

摘要 本综述挑战湿法冶金领域的共识，即钝化层会阻碍黄铜矿浸出。并非所有关于黄铜矿浸出的研究都表明表层正在钝化。一些人声称存在钝化和非钝化表面物质，但对于哪种起钝化作用存在直接相反的意见。更常见的钝化方案是缺乏金属的硫化物或缺乏金属的多硫化物的变体。有时声称它们是具有不同钝化能力的截然不同的物种，有时它们只是同一事物的不同名称。这些没有明确定义，通常被赋予一个通用名称，例如 Cu1-xFe1-yS2 或 CuFe1-xS2，这通常是从电化学和溶解化学计量推断出来的。与酸性溶液中的浸出相反，已经表明在具有络合剂的碱性溶液中没有钝化作用。尽管表面上存在与酸溶液中发现的相同的假定钝化物质。对各种钝化方案的另一种解释是，黄铜矿的电子结构决定了在电化学和浸出中观察到的效应。天然黄铜矿具有 n 型半导体的电子结构。因此，在达到“击穿”电位之前，预计不会在适度的阳极电位下传导大量电流。这种半导体特性经常在电化学中观察到，在高达约 1.0 V (vs SHE) 的外加电位下观察到非常低的电流，其中观察到电流的快速增加。其他观察结果，如光电流、电容趋势和极限电流也归因于黄铜矿的半导体性质。然而，这种方法招致了极其强烈的批评。相反，这些批评者提出，由于天然样品中存在预期的金属杂质，黄铜矿应被视为“伪金属”而不是半导体。观察到的任何半导体效应都被认为是由于实验室设备操作不当或实验造成的。然而，仔细分析这些批评者的主张表明他们大多是推测性的——事实上，有些是基于不完整的数据和对其他已发表作品的误解。需要更客观的实验研究来验证这些批评并证明表面层确实是钝化的。