In this paper the relationship between the flotation performance of phosphate collectors and their adsorption behavior was evaluated using a variety of techniques including the Crystal Microbalance with Dissipation technique (QCM-D). The adsorption of the collectors on the surface of hydroxyapatite was primarily characterized using QCM-D, which is a high sensitivity in-situ surface characterization technique. Additionally, the collectors were evaluated via zeta potential and FTIR analyses. The flotation performance of the collectors was evaluated using a laboratory mechanical flotation cell at different process parameters such as pH, collector dosage, diesel dosage and flotation time. The two collectors evaluated were a commercial plant collector and a refined tall oil fatty acid. The QCM-D data showed that the refined tall oil fatty acid adsorbed on phosphate more readily and produced stronger hydrophobicity and better flotation performance than the plant collector. The chemisorption and surface precipitation mechanisms of the refined tall oil fatty acid on the surface of hydroxyapatite were demonstrated by means of zeta potential measurements and FTIR analysis.