Abstract: The environmental impact of mining on the ecosystem, including land, water and air, has become an unavoidable reality. Guidelines and regulations have been promulgated to protect the environment throughout mining activities from start-up to site decommissioning. In particular, the occurrence of acid mine drainage (AMD), due to oxidation of sulfide mineral wastes, has become the major area of concern to many mining industries during operations and after site decommissioning. AMD is characterized by high acidity and a high concentration of sulfates and dissolved metals. If it cannot be prevented or controlled, it must be treated to eliminate acidity, and reduce heavy metals and suspended solids before release to the environment. This paper discusses conventional and new methods used for the treatment of mine effluents, in particular the treatment of AMD.

Abstract: The understanding of molecular mechanisms in the cycling of elements in general is essential to our alteration of current processes. One field where such geochemical element cycles are of major importance is the prevention and treatment of acid mine drainage waters (AMD) which are prone to occur in every anthropogenic, modified landscape where sulfidic rock material has been brought to the surface during mine operations. Microbiologically controlled production of AMD leads not only to acidification, but at the same time the dissolution of heavy metals makes them bioavailable posing a potential ecotoxicological risk. The water path then can contaminate surface and ground water resources which leads to even bigger problems in large catchment areas. The investigation of mechanisms in natural attenuation has already provided first ideas for applications of naturally occurring bioremediation schemes. Especially an improved soil microflora can enhance the natural attenuation when adapted microbes are applied to contaminated areas. Future schemes for plant extraction, control of water efflux by increasing evapotranspiration, and by subsequent land use with agricultural plants with biostabilization and phytosequestration potential will provide putative control measures. The mechanisms in parts of these processes have been evaluated and the resulting synthesis applied to derive a bioremediation plan using the former uranium mine in Eastern Thuringia as a case study. (c) 2005 Elsevier GrnbH. All rights reserved.

Abstract: The utilization of saline coal mine waters is considered to be the most adequate method of solving ecological problems caused by this kind of water in Poland. In the case of most concentrated waters, the so-called coalmine brines, the method of concentrating by evaporation in a twelve-stage expansion installation or vapour compression is applied, after which sodium chloride is manufactured. A considerable restriction in the utilization of coal mine brines is the high energy consumption in these methods of evaporation. An obstacle in the application of low energy evaporation processes, e.g. multi-stage flash, is the high concentration of calcium and sulfate ions in the coal mine brines. The present paper deals with the application of nanofiltration in the pretreatment of the brine. The application of nanofiltration membranes with an adequate pore size, including charged membranes, makes it possible to decrease the concentration of divalent ions in the permeate practically without any changes in the concentration of sodium chloride. Then the permeate may be concentrated in a multi-stage evaporation process, e.g. MSF, without any risk of the crystallization of gypsum. A combination of NF and MSF ought to set down the unit costs of the concentration of coal mine brines below those of mere evaporation.