Many laboratory studies are completed each year exploring the flotation response of old and new ore sources. Most pay little attention to the impact grinding media has on down stream processing or even attempt to match the laboratory grinding chemistry to comparable plant data. The Magotteaux Mill(R), described in this paper, allows the user to measure, monitor and control the pulp chemical conditions during grinding. This ultimately means that it is now possible to prepare ore samples in the laboratory that have the same properties as those in the plant (i.e. particle size distribution and pulp chemistry). (C) 2004 Elsevier Ltd. All rights reserved.