Matches in SemOpenAlex for { <https://semopenalex.org/work/W2004356714> ?p ?o ?g. }
- W2004356714 endingPage "73" @default.
- W2004356714 startingPage "46" @default.
- W2004356714 abstract "Despite the wealth of published data on the beneficial or detrimental effects of silver, lead, sulfide, and carbonaceous matter on the rate of gold cyanidation at an anode or by dissolved oxygen, the lack of comparative studies on relative effects has hampered rationalisation of the role of these activators or passivators of gold. In the present study, the published rate data per unit surface area of gold, silver, and gold–silver alloys based on electrochemical or chemical dissolution of rotating discs or foils of constant surface area in aerated cyanide solutions at ambient temperatures are analysed on the basis of the Levich equation. The current status of the reaction mechanism is also reviewed and updated on the basis of species distribution and potential–pH diagrams, stoichiometric factors, and interim chemical species of gold(I), silver(I), and lead(II). The anodic peak potentials of reported voltammograms closely follow the potential–pH lines of Au(I)/Au(0) and Pb(II)/Pb(0) couples. Despite the formation of stable complexes between lead(II), nitrate, and hydroxide ions, the total calculated soluble lead(II) in alkaline solutions of pH range 10–11 saturated with lead hydroxide is shown to be < 0.1 g/m3. A comparison of the reported diffusion coefficients of cyanide ions and dissolved oxygen with the values based on the Levich plots of reported rates reveals the rate-controlling stoichiometric M/CN or M/O2 molar ratios. The difference between some of these ratios and the generally accepted ratios of M/CN = 1/2 and M/O2 = 1/0.5 or 1/0.25 based on the formation of M(CN)2−, H2O2 or OH− in the overall cyanidation reaction is attributed to the oxidation of cyanide to cyanate and passivation due to the formation of gold hydroxides/oxides. The alloyed or dissolved silver and lead eliminate passivation due to the involvement of mixed hydroxo–cyano complexes of silver and lead ions in the surface reaction. Gold dissolution by oxygen in cyanide-rich solutions is limited by oxygen diffusion, but enhanced by the presence of a low concentration of sodium sulfide due to the involvement of hydrosulfide ion in the surface reaction. However, excess lead or sulfide retards gold cyanidation due to surface blockage by metallic lead, lead hydroxide, or due to passivation by Au2S/S. Even low concentrations of hydrosulfide passivate gold–silver alloys due to the formation of Ag2S. This can be eliminated by adding stoichiometric quantities of lead(II) to precipitate sulfide as PbS. Large stoichiometric ratios of O2/M for the cyanidation of graphite coated gold appears to be a result of the enhanced oxidation of cyanide by oxygen or hydrogen peroxide, leading to a cyanide deficiency at the surface and passivation of gold by hydroxide/oxide. The presence of excess cyanide or lead(II) does not override this effect." @default.
- W2004356714 created "2016-06-24" @default.
- W2004356714 creator A5007934113 @default.
- W2004356714 date "2008-01-01" @default.
- W2004356714 modified "2023-10-17" @default.
- W2004356714 title "A review of effects of silver, lead, sulfide and carbonaceous matter on gold cyanidation and mechanistic interpretation" @default.
- W2004356714 cites W151409800 @default.
- W2004356714 cites W1538784542 @default.
- W2004356714 cites W1963949276 @default.
- W2004356714 cites W1964128579 @default.
- W2004356714 cites W1964134662 @default.
- W2004356714 cites W1964304864 @default.
- W2004356714 cites W1965361514 @default.
- W2004356714 cites W1966157758 @default.
- W2004356714 cites W1967583466 @default.
- W2004356714 cites W1968944948 @default.
- W2004356714 cites W1969904358 @default.
- W2004356714 cites W1973389313 @default.
- W2004356714 cites W1974888912 @default.
- W2004356714 cites W1975862444 @default.
- W2004356714 cites W1978765357 @default.
- W2004356714 cites W1980461905 @default.
- W2004356714 cites W1980561671 @default.
- W2004356714 cites W1984558056 @default.
- W2004356714 cites W1984842997 @default.
- W2004356714 cites W1985542076 @default.
- W2004356714 cites W1987483531 @default.
- W2004356714 cites W1987709182 @default.
- W2004356714 cites W1987818914 @default.
- W2004356714 cites W1987929838 @default.
- W2004356714 cites W1988992024 @default.
- W2004356714 cites W1990316570 @default.
- W2004356714 cites W1990865427 @default.
- W2004356714 cites W1991270319 @default.
- W2004356714 cites W1991434020 @default.
- W2004356714 cites W1994432457 @default.
- W2004356714 cites W1995964992 @default.
- W2004356714 cites W1999339999 @default.
- W2004356714 cites W2000078494 @default.
- W2004356714 cites W2002179919 @default.
- W2004356714 cites W2005178440 @default.
- W2004356714 cites W2006725724 @default.
- W2004356714 cites W2006737361 @default.
- W2004356714 cites W2006833352 @default.
- W2004356714 cites W2009809840 @default.
- W2004356714 cites W2011768606 @default.
- W2004356714 cites W2017907256 @default.
- W2004356714 cites W2022447654 @default.
- W2004356714 cites W2022818590 @default.
- W2004356714 cites W2025911977 @default.
- W2004356714 cites W2027231250 @default.
- W2004356714 cites W2032670981 @default.
- W2004356714 cites W2035284052 @default.
- W2004356714 cites W2036442964 @default.
- W2004356714 cites W2037660965 @default.
- W2004356714 cites W2037883051 @default.
- W2004356714 cites W2040769006 @default.
- W2004356714 cites W2040937457 @default.
- W2004356714 cites W2044985857 @default.
- W2004356714 cites W2047711190 @default.
- W2004356714 cites W2053755684 @default.
- W2004356714 cites W2053958819 @default.
- W2004356714 cites W2055234683 @default.
- W2004356714 cites W2057441386 @default.
- W2004356714 cites W2058755975 @default.
- W2004356714 cites W2060232238 @default.
- W2004356714 cites W2060258565 @default.
- W2004356714 cites W2061090265 @default.
- W2004356714 cites W2063089353 @default.
- W2004356714 cites W2069360102 @default.
- W2004356714 cites W2076855465 @default.
- W2004356714 cites W2088064138 @default.
- W2004356714 cites W2088466727 @default.
- W2004356714 cites W2091447008 @default.
- W2004356714 cites W2093828204 @default.
- W2004356714 cites W2094701955 @default.
- W2004356714 cites W2107936421 @default.
- W2004356714 cites W2137970017 @default.
- W2004356714 cites W2143403876 @default.
- W2004356714 cites W2203597597 @default.
- W2004356714 cites W2312267001 @default.
- W2004356714 cites W4250723652 @default.
- W2004356714 cites W60705086 @default.
- W2004356714 doi "https://doi.org/10.1016/j.hydromet.2007.09.013" @default.
- W2004356714 hasPublicationYear "2008" @default.
- W2004356714 type Work @default.
- W2004356714 sameAs 2004356714 @default.
- W2004356714 citedByCount "73" @default.
- W2004356714 countsByYear W20043567142012 @default.
- W2004356714 countsByYear W20043567142013 @default.
- W2004356714 countsByYear W20043567142014 @default.
- W2004356714 countsByYear W20043567142015 @default.
- W2004356714 countsByYear W20043567142016 @default.
- W2004356714 countsByYear W20043567142017 @default.
- W2004356714 countsByYear W20043567142018 @default.
- W2004356714 countsByYear W20043567142019 @default.
- W2004356714 countsByYear W20043567142020 @default.
- W2004356714 countsByYear W20043567142021 @default.