As a result of the thermodynamic analysis of apatite-sodium oleate-water system, spectroscopic investigations, and flotation tests at various pH values and sodium oleate concentrations it has been established that optimal conditions for calcium oleate formation and apatite flotation are different. The novel hypothesis, connecting optimal conditions for apatite flotation with zero charge of mineral surface, allowed us to explain the regularity of apatite flotation observed, elaborate a quantitative physicochemical model of apatite flotation and explain the optimal conditions for selective flotation of carbonate and phosphates on an industrial scale.