Sodium cyanide hazards to fish and other wildlife from gold mining operations

By: , and 
Edited by: Jose M. Azcue



Highly toxic sodium cyanide (NaCN) is used increasingly by the international mining community to extract gold and other precious metals through milling of high grade ores and heap leaching of low grade ores. Of the 98 million kg cyanide (CN) consumed in North America in 1989, about 80% was used in gold mining (Knudson 1990). In Canada, more than 90% of the mined gold is extracted from ores with the cyanidation process. This process consists of leaching gold from the ore as a gold-cyanide complex, and gold being recovered by precipitation (Simovic and Snodgrass 1985). Milling and heap leaching require cycling of millions of liters of alkaline water containing high concentrations of potentially toxic NaCN, free cyanide, and metal cyanide complexes that are frequently accessible to wildlife. Some milling operations result in tailings ponds of 150 ha and larger. Heap leach operations that spray or drip cyanide solution onto the flattened top of the ore heap require solution processing ponds of about 1 ha in surface area. Although not intentional or desired, puddles of various sizes may occur on the top of heaps where the highest concentrations of NaCN are found. Exposed solution recovery channels are usually constructed at the base of leach heaps. All of these cyanidecontaining water bodies are hazardous to wildlife if not properly managed (Henny et al. 1994). In this account we emphasize hazards of cyanide from mining operations to fish and wildlife species and proposed mitigation to protect them.

Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Sodium cyanide hazards to fish and other wildlife from gold mining operations
DOI 10.1007/978-3-642-59891-3_5
Year Published 1999
Language English
Publisher Springer-Verlag
Publisher location Berlin
Contributing office(s) Columbia Environmental Research Center, Patuxent Wildlife Research Center, Forest and Rangeland Ecosystem Science Center
Description 13 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Environmental impacts of mining activities: Emphasis on mitigation and remedial measures
First page 55
Last page 67