Phosphate flotation has been used by industry for more than a half century but still faces many technical challenges. Such challenges include not only the selection of the chemical reagents but the characteristics of the feed itself. This paper deals with the investigation of feed characteristics and how these characteristics affect the flotation separation efficiency of feed material from a selected phosphate operation. Specifically why some feed, from the same mine, is efficiently separated with high recovery (good feed) while other feed is more difficult to separate (bad feed). The study was conducted using both traditional analytical techniques and more advanced techniques such as X-ray microtomography. The results reveal that the bad feed was highly porous, coarser in size, and, most significantly, exhibits a lower degree of liberation. Such bad feed was inefficiently separated by fatty acid flotation and improved recovery would require controlled grinding in order to improve the extent of liberation. (C) 2008 Elsevier Ltd. All rights reserved.