Stepwise oxidation of refractory pyrite using persulfate for efficient leaching of gold and silver by an eco-friendly copper(II)-glycine-thiosulfate system

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL Powder Technology Pub Date : 2024-09-28 DOI:10.1016/j.powtec.2024.120323

Lei Hou , Alejandro López Valdivieso , Aurora Robledo-Cabrera , Nasriddinov Zamoniddin Zainiddinovich , Chunhui Wu , Shaoxian Song , Feifei Jia

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Abstract

Chemical oxidation is a promising pretreatment method for refractory pyrite enclosure to enhance Au/Ag extraction. Here, persulfate was employed for stepwise oxidation of a refractory pyrite concentrate with encapsulated Au/Ag: (i) pyrite oxidation began with heating-activation persulfate, where hydroxyl radical (•OH) acted as the primary oxidative species for fast-dissolving pyrite into Fe ions; (ii) pyrite self-dissolved Fe ions were in-suit used as a moderate activator of persulfate to generate •OH for sustainable oxidizing pyrite at room temperature. Mineralogical studies have confirmed that oxidation of the sulfide enclosure (FeS₂) significantly reduced the particle size of pyrite, accompanied by pores creation and an increase in specific surface area. The variation of microstructure liberated Au and Ag particles to lixiviants for extraction, significantly improving leaching efficiency in an eco-friendly copper(II)-glycine-thiosulfate system to 92.2 % for Au and 88.6 % for Ag, respectively. This work provides a promising process for separating precious metals from refractory pyrite.

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利用过硫酸盐分步氧化难熔黄铁矿，通过生态友好型铜(II)-甘氨酸-硫代硫酸盐体系高效浸出金银

化学氧化是一种很有前景的难选黄铁矿围岩预处理方法，可提高金/银的提取率。在此，我们采用过硫酸盐对封装了金/银的难处理黄铁矿精矿进行了分步氧化：(i) 黄铁矿氧化从加热活化过硫酸盐开始，羟基自由基（-OH）作为主要氧化物种，可将黄铁矿快速溶解为铁离子；(ii) 黄铁矿自溶的铁离子可作为过硫酸盐的适度活化剂，以产生-OH，从而在室温下持续氧化黄铁矿。矿物学研究证实，硫化物外壳（FeS2）的氧化作用大大减小了黄铁矿的粒度，同时产生了孔隙，增加了比表面积。微观结构的变化将金和银颗粒释放到萃取用的活化剂中，大大提高了环保型铜（II）-甘氨酸-硫代硫酸盐体系的萃取效率，金和银的萃取效率分别达到 92.2% 和 88.6%。这项工作为从难选冶黄铁矿中分离贵金属提供了一种前景广阔的工艺。

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来源期刊

Powder Technology 工程技术-工程：化工

CiteScore

9.90

自引率

15.40%

发文量

1047

审稿时长

46 days

期刊介绍： Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests: Formation and synthesis of particles by precipitation and other methods. Modification of particles by agglomeration, coating, comminution and attrition. Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces). Packing, failure, flow and permeability of assemblies of particles. Particle-particle interactions and suspension rheology. Handling and processing operations such as slurry flow, fluidization, pneumatic conveying. Interactions between particles and their environment, including delivery of particulate products to the body. Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters. For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.