Fractional precipitation of copiapite-halotrichite efflorescent salts on AuCu mine tailings under semi-arid climates in northern Chile

IF 3.4 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS
Javiera Gerding , Juan Morales , Alexey A. Novoselov , Santos Barrios Sánchez
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引用次数: 0

Abstract

The oxidation of pyrite involves a series of chemical reactions that, depending on climatic conditions, can give rise to different mineral phases and morphologies. When oxidation takes place in semi-arid climate, the development of efflorescent salts on the surface of mine tailings is characteristic. These salts are mainly composed of Fe, Al and Mg sulfates and may accumulate valuable metals liberated through the dissolution of tailing minerals.

This research aims to describe the evolution of salt precipitation from the economic and environmental perspective. For this purpose, we sampled efflorescent salts formed during the summer season on the surface of a tailing impoundment located in the north of Chile. The materials underwent comprehensive characterization utilizing X-ray techniques and scanning electron microscopy.

The findings reveal a fractional precipitation in the crystallized salts. In an advanced oxidation system, characterized by multiple seasons of crystallization, dissolution and oxidation, the dry season begins with the precipitation of sulfates from a highly acidic solution dominated by Fe3+. This solution results from the dissolution and oxidation of the previous season sulfates. This initial stage is characterized by the presence of jarosite and gypsum, which are subsequently replaced by ferricopiapite. Towards the progress of the dry season, copiapite becomes more magnesian and precipitates alongside coquimbite and alunogen. Finally, halotrichite and pickeringite begin to crystallize. Base metal cations such as Co, Cu, Mn, Ni and Zn are preferentially incorporated into halotrichite-pickeringite sulfates during the most advanced evaporation phase.

智利北部半干旱气候条件下金铜矿尾矿上共沸石-海绿石逸出盐的分馏沉淀
黄铁矿的氧化过程涉及一系列化学反应,根据气候条件的不同,会产生不同的矿物相和形态。在半干旱气候条件下发生氧化作用时,矿山尾矿表面会形成特有的泡沫盐。这些盐类主要由铁、铝和镁硫酸盐组成,并可能积聚通过溶解尾矿矿物而释放出的有价金属。为此,我们对位于智利北部的一个尾矿库表面在夏季形成的析出盐进行了取样。我们利用 X 射线技术和扫描电子显微镜对这些材料进行了全面的表征。在以多季结晶、溶解和氧化为特征的高级氧化系统中,旱季开始时,硫酸盐从以 Fe3+ 为主的高酸性溶液中沉淀出来。这种溶液是前一季硫酸盐溶解和氧化的结果。在这一初始阶段,会出现铁石棉和石膏,随后会被铁闪长岩所取代。随着旱季的到来,辉绿岩的镁含量增加,并与铜绿岩和矾土一起沉淀下来。最后,光卤石和泡沸石开始结晶。在最后期的蒸发阶段,钴、铜、锰、镍和锌等贱金属阳离子会优先融入光卤石-黝帘石硫酸盐中。
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来源期刊
Journal of Geochemical Exploration
Journal of Geochemical Exploration 地学-地球化学与地球物理
CiteScore
7.40
自引率
7.70%
发文量
148
审稿时长
8.1 months
期刊介绍: Journal of Geochemical Exploration is mostly dedicated to publication of original studies in exploration and environmental geochemistry and related topics. Contributions considered of prevalent interest for the journal include researches based on the application of innovative methods to: define the genesis and the evolution of mineral deposits including transfer of elements in large-scale mineralized areas. analyze complex systems at the boundaries between bio-geochemistry, metal transport and mineral accumulation. evaluate effects of historical mining activities on the surface environment. trace pollutant sources and define their fate and transport models in the near-surface and surface environments involving solid, fluid and aerial matrices. assess and quantify natural and technogenic radioactivity in the environment. determine geochemical anomalies and set baseline reference values using compositional data analysis, multivariate statistics and geo-spatial analysis. assess the impacts of anthropogenic contamination on ecosystems and human health at local and regional scale to prioritize and classify risks through deterministic and stochastic approaches. Papers dedicated to the presentation of newly developed methods in analytical geochemistry to be applied in the field or in laboratory are also within the topics of interest for the journal.
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