The TCLP and its applicability for the characterization of worst case leaching of wastes from Mining and Metallurgical operations

Abstract

Laboratory batch extraction tests, such as the Toxicity Characteristic Leaching Procedure (TCLP), are widely used to classify industrial solid wastes destined for disposal in landfills. Whilst the ease and speed of such tests makes their use an attractive option, it is also immediately clear that the physical and chemical mechanisms dominating in such tests do not bear much resemblance to those expected in a landfill situation. Neither can tests of such short duration be expected to identify long term effects which, if present, are likely to dominate leachate generation behaviour once the waste is disposed. This paper discusses the mechanisms involved in leaching. A series of tests on a metallurgical waste (an EAF dust) is reported which aimed to identify the appropriateness of the TCLP in characterising worst case leaching for this type of material. The results are discussed together with some more theoretical aspects of leaching to assess the applicability of the TCLP for wastes from the mining and metallurgical operations. It is concluded that some of the physical and chemical parameters defining the TCLP require some flexibility in order to create adequate worst case scenarios for each particular waste material.