Environmental Mineralogy: Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management
The past 10 years or so have seen the emergence of a discipline known as ‘Environmental Mineralogy’. This should be regarded not as a new discipline per se, but as a new application of traditional mineralogy. Mineralogists have always sought to understand the chemical and physical environment under which a particular mineral forms and to determine the arrangement of atoms within that mineral. The field of Environmental Mineralogy asks the same questions in a different context. For example, can minerals assist in the remediation of contaminated soils and waters? Which minerals can potentially be deleterious to, inter alia, buildings, ecology and human health? Which minerals are suitable as containment for waste? How does the biota interact with minerals? Environmental Mineralogy is emerging as a field that seeks to define the roles of minerals in all environmental systems, and to work towards the preservation and restoration of such systems. Environmental Mineralogy is achieving prominence because of increasing concern regarding the environments in which we live. Mineralogists have perceived a gap in our understanding of how minerals behave in the surface environment and a need for innovative,‘green’ solutions to the problems of contamination and waste. However, the emergence of Environmental Mineralogy also owes much to modern analytical technology. Many minerals in the surface environment fall within the clay-grade range and therefore, demand high-resolution systems for analysis. Similarly, trace elements are now detectable at exceptionally low concentrations in a wide variety of matrices. Further, many mineral-environment interactions need to be examined at the atomic scale for a greater understanding of the interactive processes involved. This requires the application of the latest technologies such as X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and atomic force microscopy to name but a few. The aim of this monograph is to provide an up-to-date account of the state of this diverse subject area. With chapters containing a strong review element, it is hoped that this volume will appeal to both researchers and students alike. The volume is arranged in four sections: (1) mineral-microbe interactions; (2) anthropogenic influences on mineral interactions; (3) minerals in contaminated environments; and (4) minerals and waste management. These four sections by no means give exhaustive coverage of the subject area, but communicate some of the most important developments taking place at the present time.
Mechanisms and rates of sulphide oxidation in relation to the problems of acid rock (mine) drainage
Published:January 01, 2000
C. N. Keith, D. J. Vaughan, 2000. "Mechanisms and rates of sulphide oxidation in relation to the problems of acid rock (mine) drainage", Environmental Mineralogy: Microbial Interactions, Anthropogenic Influences, Contaminated Land and Waste Management, J. D. Cotter-Howells, L. S. Campbell, E. Valsami-Jones, M. Batchelder
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The aqueous oxidation of metal sulphide minerals in natural rocks, minewastes or mineworkings generates acidic waters, often containing elevated concentrations of toxic metals, and known as acid mine drainage (AMD)or, more generally, as acid rock drainage (ARD). Understanding the mechanisms and rates of oxidation of key sulphide minerals is the essential first stage in understanding the processes giving rise to ARD. In this chapter, our knowledge of the aqueous oxidation of the most important sulphide minerals (pyrite, pyrrhotite, galena, chalcopyrite, sphalerite, marcasite and arsenopyrite) is considered in the context of problems associated with ARD.
In certain cases, qualitative or semi-quantitative data concerning oxidation rates are available (for example, in tailings impoundments the sequence from most to least reactive is generally pyrrhotite > galena - sphalerite > pyrite - arsenopyrite > chalcopyrite)and a substantial body of data (some conflicting)exists concerning the products of oxidation. It is acknowledged that surface reaction control is the key to oxidation reaction mechanism. However, as reviewed here, the data and models currently available to describe the oxidation of particular sulphides do not, as yet, yield a consistent picture. Fundamental understanding of oxidation mechanisms remains sketchy, therefore, but the tools are now available to make progress in this field through in situ studies of oxidation processes at atomic resolution.