In the assessment of acid rock drainage and metal leaching potential for a mine the standard approach is to assess each lithogy, in conjunction with alteration and/or ore type. These variations in lithogies are then referred to as material types and further sub-classified into either reactive or inert waste materials, and ore in order to define their disposal or storage requirements. However, these materials are often classified in the early stages of a project at the prefeasibility or feasibility stage and remain classified as such for the duration of the geochemical assessment. Subsequent changes in project economics can lead to the need for a reclassification of materials, but it is often difficult to relate these back to samples in the geochemical testing. During the recent feasibility study of the Fedorovo Project, located on the Kola Peninsula, in the North West of Russia, net smelter return was added to the material type classification system to address this issue.
