Impact of silver sulphide on gold cyanidation with conductive sulphide minerals

Abstract

Gold is mostly found in metallic form, while silver exists in various mineral forms. Pyrite, chalcopyrite, sphalerite, and stibnite were the sulphidic minerals investigated for the effect of silver sulphide on gold cyanidation. Four sets of mineral systems, pyrite‐silica, chalcopyrite‐silica, sphalerite‐silica, and stibnite‐silica, were established to investigate the effect of silver sulphide. Silver sulphide addition promoted gold dissolution for the pyrite‐silica and sphalerite‐silica systems. The gold dissolution was retarded with the chalcopyrite‐silica and stibnite‐silica systems, irrespective of the dispersion of gold and silver sulphide in the mineral as well as in the quartz layer. The surface characterization of the gold particles was attempted by using X‐ray photoelectron spectroscopy (XPS) in order to identify the surface obstructing species. XPS analysis showed that the passivation layers of silver sulphide (Ag2S), Cu2O/Cu(OH)2, and antimony oxide (Sb2O5) might form on the surface of goldparticles by the simultaneous dissolution of silver sulphide as well as sulphide minerals, resulting in the retardation of gold dissolution.

The role of silver minerals on the cyanidation of gold particles embedded within multi‐sulphidic mineral matrices

“…Alternative operational strategies may be put in place to mitigate cyanide consumption such as through reducing the contact time between the ore and the cyanide solution, not to mention that other leaching agents are even being explored as substitutes to cyanide for gold leaching. Gold‐sulphide galvanic interactions were shown to remarkably influence the gold leaching behaviour . The factors affecting the kinetics of gold leaching in aerated cyanide solutions are mostly of a mineralogical nature.…”

“…The role of silver is to de‐passivate the surface of gold—via a bimetallic corrosion—which is passivated by the formation of an AuCN(s) film on its surface . Under the cyanidation conditions prevailing in the gold industry, recovery of silver is much less than that of recovered gold, which could be attributed to the presence of poorly soluble silver minerals . In the case of high‐grade silver‐bearing gold ores, gold is usually present in metallic form.…”

“…However, there are over 200 known argentiferous mineral species where silver is usually associated with polymetallic sulphides and sulphosalts. Economically, significant silver phases include metallic silver [Ag], acanthite [Ag 2 S], pyrargyrite [Ag 3 SbS 3 ], proustite [Ag 3 AsS 3 ], aguilarite [Ag 4 SeS], and tetrahedrite [(Cu,Fe,Ag,Zn) 12 Sb 4 S 13 ] …”

“…The modalities that were investigated hitherto concerned: i) the effect of metallic silver (Ag) on the kinetics of gold leaching whether mixed or segregated from single‐sulphide minerals, ii) the impact of silver sulphides on the dissolution kinetics of gold embedded within a single base‐metal sulphide layer. The effect of pre‐treatment and additives was investigated as well on the leaching kinetics of gold in association with silver minerals and single base‐metal sulphides …”

Preface of the 66th Canadian Chemical Engineering Conference: “Sustainability and Prosperity”

“…This special issue section would have not materialized without the efforts of the contributing authors and the reviewers to ensure, despite their busy schedules, that all accepted papers meet the quality standards of The Canadian Journal of Chemical Engineering . The guest editors are also sincerely thankful to the Editor‐in‐Chief of The Canadian Journal of Chemical Engineering , Prof. João Soares, for his support and guidance, and to his editorial staff for their efforts, in welcoming this series of papers on timely topics.…”