Novel environmental management application for lignite

Abstract

Mining and mineral processing operations are usually generating huge amount of tailings. These tailings often gives lots of maintenance work in order to protect environmental resources from heavy metals slowly leaching out of tailing are due to Acid Rock Drainage (ARD) process. Handling leakage could be active or passive such as using of Permeable Reactive Barriers (PRB). Using PRB technology water is not extracted, however PRB’s are built underground in the way of underground waters where contaminants are extracted or conversed into harmless components on the surface of the PRB matrix material (Madarász, Tóth, 2010). One of the most important criteria for using PRB to select or design the proper material for matrix material on which the contaminant adsorbs, precipitate or degrade. Water is able to going through the barrier and on the downstream side, clarified water is going to be released PRB’s are used worldwide treating underground contaminations, using different type of matrix materials. All generally used matrix material has its advantages and disadvantages such as selectivity, sensitivity of precipitation generation or not satisfying hydraulic conductivity. Nowadays cheap and effective matrix material which is ignorant to pore plugging caused by precipitation within the PRB could be one solution to the demands of the industry. The authors have been carried out an investigation at University of Miskolc on lignite as high humid acid containing material for determining the ability of heavy metal adsorption and pore plugging resistance. Moreover, using hydraulic and chemical simulation methods, complete PRB dimensioning protocol based on new lignite matrix had been introduced. Adsorption capacity of tested lignite samples were determined for toxic transient and heavy metal cations. Static and dynamic adsorption tests had been carried out parallel in order to investigate adsorption kinetics, while hydrodynamic and transport modelling also had been done. As a result of the research, a complex design protocol for lignite based PRB system had been established of which are being discussed within the frame of this paper.