The Environmental Geochemistry of Cyanide
A.C.S. Smith, T.I. Mudder, 1997. "The Environmental Geochemistry of Cyanide", The Environmental Geochemistry of Mineral Deposits: Part A: Processes, Techniques, and Health Issues Part B: Case Studies and Research Topics, G.S. Plumlee, M.J. Logsdon, L.F. Filipek
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“His ways precedeth his coming. We speaketh his name in fear and trembling (Anon, circa 451 AD).” Obscure perhaps, but these words of the Roman centurion about his foe Attila the Hun, immediately prior to the defeat of Attila at the Battle of Chalons-sur- Marne in 451 AD, reflect a similar perception within the community of the nature of cyanide. The status of cyanide as a social and environmental pariah is not founded in the technical literature but is emotionally driven, consequent perhaps from the historic use of cyanide by the agencies of law enforcement in the United States and in other jurisdictions to carry out capital punishment.
However, a technically based evaluation of the nature and behavior of cyanide in the environment leads to a more sympathetic view of the potential impact of this widely used industrial and mining chemical. In this chapter, we review the environmental geochemistry of cyanide in mining applications. We will first consider the extraction process chemistry for precious metal ores, a chemical process in which cyanide is a vital ingredient. We will then describe fundamental aspects of cyanide chemistry, and translate this chemistry to geochemical reactions and processes. The application of these processes and reactions forms the root of how cyanide migration and attenuation in the natural environment can be evaluated.
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The Environmental Geochemistry of Mineral Deposits: Part A: Processes, Techniques, and Health Issues Part B: Case Studies and Research Topics
Environmental issues have become important, if not critical, factors in the success of proposed mining projects worldwide. In an ongoing and intense public debate about mining and its perceived environmental impacts, the mining industry points out that there are many examples of environmentally responsible mining currently being carried out (e.g., Todd and Struhsacker, 1997). The industry also emphasizes that the majority of mining-environmental problems facing society today are legacies from the past when environmental consequences of mining were poorly understood, not regulated, or viewed as secondary in importance to societal needs for the resources being extracted. On the other hand, environmental organizations (e.g., Mineral Policy Center, 1999) point to recent environmental problems, such as those stemming from open-pit gold mining at Summitville, Colorado, in the late 1980s (see Summitville summaries in Posey et al., 1995; Danielson and Alms, 1995; Williams, 1995; Plumlee, 1999), or those associated with a 1998 tailings dam collapse in Spain (van Geen and Chase, 1998), as an indication that environmental problems (whether accidental or resulting from inappropriate practices) can still occur in modern mining. Recent legislation imposing a moratorium on new mining in Wisconsin, and banning new mining in Montana using cyanide heap-leach extraction methods further underscore the seriousness of the debate and its implications for mineral resource extraction.
In this debate, one certainty exists: there will always be a need for mineral resources in developed and developing societies. Although recycling and substitution will help meet some of the worlds resource needs, mining will always be relied upon to meet the remaining needs. The challenge will be to continue to improve the ways in which mining is done so as to minimize its environmental effects.
The earth, engineering, and life sciences (which we group here under the term “earth-system sciences,” or ESS for short) provide an ample toolkit that can be drawn upon in the quest for environmentally friendly mineral resource development. The papers in this two-part volume provide many details on tools in the scientific toolkit, and how these tools can be used to better understand, anticipate, prevent, mitigate, and remediate the environmental effects of mining and mineral processing.
As with any toolkit, it is the professional’s responsibility to choose the tool(s) best suited to a specific job. By describing the tools now available, we do not mean to imply that all of these tools need even be considered at any given site, nor that