Static-Test Methods Most Commonly Used to Predict Acid-Mine Drainage: Practical Guidelines for Use and Interpretation
W.W. White, III, K.A. Lapakko, R.L. Cox, 1997. "Static-Test Methods Most Commonly Used to Predict Acid-Mine Drainage: Practical Guidelines for Use and Interpretation", 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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Acid mine drainage (AMD) is contaminated effluent from mines and mining wastes that results from the oxidation of iron-sulfide minerals exposed to air and water. The intensity and duration of AMD formation are complex functions of deposit geology, mineralogy, and hydrology, and the subsequent interaction of climactic conditions upon ore and waste when exposed by various mining methods. Because AMD can produce effluent containing acid- and heavy-metal concentrations that exceed water quality standards and is perceived as irreversible once started, it is one of the more vexing environmental problems facing land-managing agencies and the minerals industry today. Consequently, reliable prediction tools that quantify the risk for a particular mine waste to produce AMD are actively sought by the minerals industry and regulators.
Today numerous tools in the form of various laboratory “static”- and “kinetic”-predictive tests are available for fees that range from $35 to as much as $5,200 per sample. Static tests are short term (usually measured in hours or days) and relatively low cost per sample (from $35 to $135). Their objective is to provide an estimate of a mine waste's capacity to produce acid and its capacity to neutralize acid. One shortcoming of static tests is that they measure only the capacities for acid production and consumption and do not consider the differences between the respective dissolution rates of acid-producing and acid-consuming minerals. Another potential source of error inherent to static-test-data interpretation is the assumption that all acid-producing and acid-consuming minerals present will react completely, an assumption which ignores the influence of acid-producing and acid-consuming mineral particle-size and morphology.
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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