Optimizing the flotation performance of fine particles has long been a focus of researchers in the area of mineral processing. One of the major technological challenges to float fine-particle size fractions is the lack of smaller bubble sizes in the flotation equipment. Therefore, dissolved air flotation, where the size of most bubbles is less than 100 mu m, can encounter problems that are inherent to the flotation of smaller particle sizes. Thus, this paper investigated the effect of some process variables on the performance of the dissolved air flotation of fine phosphate ore. The size distribution of the bubbles were measured. The satisfactory performance requirements that the flotation experiments must meet, i.e., P2O5 grade and apatite recovery, simultaneously, higher than 30% and 60%, were achieved. The results also allowed quantifying the influence of the analyzed variables (pulp pH, wash water flow rate, circulating load flow rate, initial solid concentration in the column, circulating load addition point and saturated water addition point) on apatite flotation yield. (c) 2012 Elsevier B.V. All rights reserved.