This paper presents the results of a liberation study made on a sulfide copper ore from Carajs, Brazil, in a mini pilot plant flotation test. The aim of the research was the methodological evaluation of a liberation study using a sample crushed at 1 mm and a sample ground for flotation testing to a target size of 80 per cent <210 m. a comparison of liberation determinations by particle area percentage and exposed particle perimeter percentage was made. the proportion of exposure of the sulfide was considered as a function of the volumetric fraction of the sulfide in the particle and the sulfide particle texture. the results were used to indicate the primary target size for grinding and to predict copper recovery from the flotation rougher stage. the liberation by grade class was also based on the sulfide content of the particles and this was used to indicate the particle size for the regrinding stage, which takes place prior to the flotation cleaner stage. recovery estimates during this work for a sample ground at 80 per cent><210 m using the exposure criterion were similar to the copper recovery obtained during the rougher stage.>