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Photochemical changes in cyanide speciation in drainage from a precious metal ore heap

Environmental Science and Technology

By:
, , , and
DOI: 10.1021/es011064s

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Abstract

In drainage from an inactive ore heap at a former gold mine, the speciation of cyanide and the concentrations of several metals were found to follow diurnal cycles. Concentrations of the hexacyanoferrate complex, iron, manganese, and ammonium were higher at night than during the day, whereas weak-acid-dissociable cyanide, silver, gold, copper, nitrite, and pH displayed the reverse behavior. The changes in cyanide speciation, iron, and trace metals can be explained by photodissociation of iron and cobalt cyanocomplexes as the solutions emerged from the heap into sunlight-exposed channels. At midday, environmentally significant concentrations of free cyanide were produced in a matter of minutes, causing trace copper, silver, and gold to be mobilized as cyanocomplexes from solids. Whether rapid photodissociation is a general phenomenon common to other sites will be important to determine in reaching a general understanding of the environmental risks posed by routine or accidental water discharges from precious metal mining facilities.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Photochemical changes in cyanide speciation in drainage from a precious metal ore heap
Series title:
Environmental Science and Technology
DOI:
10.1021/es011064s
Volume
36
Issue:
5
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Science and Technology
First page:
840
Last page:
845
Number of Pages:
6