Surface processes at a polymetallic (Mn-Fe-Pb) sulfide subject to cyanide leaching under sonication conditions and with an alkaline pretreatment: Understanding differences in silver extraction with X-ray photoelectron spectroscopy (XPS)

Gonzalo Larrabure, Sheyla Chero-Osorio, Dhamelyz Silva-Quiñones, Carsten Benndorf, Mackenzie Williams, Fei Gao, Carlos Gamarra, Alejandro Alarcón, Carlos Segura, Andrew Teplyakov, Juan Carlos F. Rodriguez-Reyes

Research output: Contribution to journalArticlepeer-review

Abstract

Leaching of polymetallic sulfides is often challenging due to the complexity of these systems. The main issues are related to the formation of surface by-products or to the presence of different metals that require a greater consumption of chemicals compared to that needed to extract the target metal during leaching. This latter case is followed in the present work using X-ray photoelectron spectroscopy (XPS) during the leaching of a silver-containing polymetallic (Mn-Fe-Pb) sulfide under three different cyanidation procedures: (1) conventional leaching, (2) ultrasound-assisted leaching, and (3) leaching of a sample pretreated in alkaline media. In all cases, leaching results in the build-up of Pb compounds (oxides/hydroxides) on the surface of the minerals, suggesting a mechanism in which Pb is first leached by hydroxide and cyanide and later is re-adsorbed as an external layer on the minerals. On the other hand, the effect of each process on Mn was quite distinct: 1) Conventional leaching leads to the oxidation of the sulfide (pyrite) surface and a slight increase of surface Mn species; 2) Ultrasound-assisted leaching decreases surface Mn by dissolving oxidized species, which exposes fresh sulfide surfaces and increases Ag extraction; and 3) An alkaline pretreatment at high temperature exposed fresh sulfide surfaces and decreased the surface concentration of Mn. The fact that ultrasound-assisted leaching and leaching after an alkaline pretreatment allow for a higher Ag extraction (60% and 75% of total Ag, respectively, as opposed to the 25% extracted via conventional leaching), indicates that leaching is more efficient if the surface is not oxidized and if Mn is removed from the samples, either before or during leaching.

Original languageEnglish
Article number105544
JournalHydrometallurgy
Volume200
DOIs
StatePublished - Mar 2021

Bibliographical note

Funding Information:
C. G. A. A. and C. S. acknowledge the support provided by the Department of Chemistry and Biochemistry at the University of Delaware during their stay in the USA. Karinna Visurraga (UTEC) is acknowledged for administrative support. This work was supported by the Phosagro/UNESCO/IUPAC Partnership in Green Chemistry for Life (Contract 4500245048); by Peru's National Council for Science, Technology and Technological Innovation (FONDECYT - CONCYTEC); and the British Embassy in Lima (contracts 154-2015 and 002-2016). The authors acknowledge the NSF (9724307; 1428149) and the NIH NIGMS COBRE program (P30-GM110758) for partial support of activities in the University of Delaware Surface Analysis Facility. None of the funding sources were involved in the data acquisition, the subsequent analysis, the writing of the paper or in the decision to submit the article for publication.

Funding Information:
This work was supported by the Phosagro/UNESCO/IUPAC Partnership in Green Chemistry for Life (Contract 4500245048 ); by Peru's National Council for Science, Technology and Technological Innovation (FONDECYT - CONCYTEC) ; and the British Embassy in Lima (contracts 154-2015 and 002-2016 ). The authors acknowledge the NSF ( 9724307 ; 1428149 ) and the NIH NIGMS COBRE program ( P30-GM110758 ) for partial support of activities in the University of Delaware Surface Analysis Facility. None of the funding sources were involved in the data acquisition, the subsequent analysis, the writing of the paper or in the decision to submit the article for publication.

Publisher Copyright:
© 2020 Elsevier B.V.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Cyanide
  • Leaching
  • Polymetallic
  • Pretreatment
  • Sonication
  • Sulfide
  • Surface analysis
  • Ultrasound-assisted
  • XPS

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