The TCLP and its applicability for the characterisation of worst case leaching of wastes from mining and metallurgical operations

Laboratory batch extraction tests, such as the Toxicity Characteristic Leac hing 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 th e physical and chemical mechanisms dominating in such tests do not bear muc h 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 wast e is disposed. This paper discusses the mechanisms involved in leaching. A series of tests on a metallurgical waste (an EAF dust) is reported which ai med to identify the appropriateness of the TCLP in characterising worst cas e leaching for this type of material. The results are discussed together wi th some more theoretical aspects of leaching to assess the applicability of the TCLP for wastes from the mining and metallurgical operations. It is co ncluded 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.