Cyanide speciation at four gold leach operations undergoing remediation
Environmental Science & Technology
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Abstract
Analyses have been made of 81 effluents from four gold leach operations in various stages of remediation to identify the most-persistent cyanide species. Total cyanide and weak acid-dissociable (WAD) cyanide were measured using improved methods, and metals known to form stable cyanocomplexes were also measured. Typically, total cyanide greatly exceeded WAD indicating that cyanide was predominantly in strong cyanometallic complexes. Iron was generally too low to accommodate the strongly complexed cyanide as Fe(CN)63- or Fe(CN)64-, but cobalt was abundant enough to implicate Co(CN)63- or its dissociation products (Co(CN)6-x(H2O)x(3-x)-). Supporting evidence for cobalt-cyanide complexation was found in tight correlations between cobalt and cyanide in some sample suites. Also, abundant free cyanide was produced upon UV illumination. Iron and cobalt cyanocomplexes both photodissociate; however, the iron concentration was insufficient to have carried the liberated cyanide, while the cobalt concentration was sufficient. Cobalt cyanocomplexes have not previously been recognized in cyanidation wastes. Their identification at four separate operations, which had treated ores that were not especially rich in cobalt, suggests that cobalt complexation may be a common source of cyanide persistence. There is a need for more information on the importance and behavior of cobalt cyanocomplexes in ore-processing wastes at gold mines.
Suggested Citation
Johnson, C.A., Grimes, D.J., Leinz, R.W., Rye, R.O., 2008, Cyanide speciation at four gold leach operations undergoing remediation: Environmental Science & Technology, v. 42, no. 4, p. 1038-1044, https://doi.org/10.1021/es702334n.
ISSN: 1520-5851 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Cyanide speciation at four gold leach operations undergoing remediation |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es702334n |
| Volume | 42 |
| Issue | 4 |
| Publication Date | January 12, 2008 |
| Year Published | 2008 |
| Language | English |
| Publisher | American Chemical Society |
| Publisher location | Easton, PA |
| Contributing office(s) | Crustal Geophysics and Geochemistry Science Center |
| Description | 7 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Environmental Science and Technology |
| First page | 1038 |
| Last page | 1044 |
| Country | United States |
| State | California;Nevada;New Mexico |