Cyanidation of Gold Associated with Silver Minerals in Sulfide Mineral Matrices

Abstract

Lead salt stimulated the dissolution of gold when gold associated with silver minerals was interspersed in the silica or in the pyrite-silica layer. Gold dissolution was likewise promoted through lead addition for chalcopyrite-silica and the sphalerite-silica systems. Lead addition did not boost gold dissolution and a recovery of 6.9 % was achieved for gold and silver minerals dispersed in stibnite. Lead pretreatment also enhanced gold recovery except for the stibnite-silica system. Gold surface-passivating films were observed for gold associated with silver minerals and stibnite.

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

“…The dissolution kinetics of the gold particles in association with silver minerals and embedded within base‐metal sulphides was investigated by using a multi‐layer packed bed reactor (PBR). The detailed description of the reactor and complete experimental setup has been explained elsewhere . The base‐metal sulphides consist of pyrite, chalcopyrite, sphalerite, and stibnite.…”

“…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 …”