Applied mineralogy has been developed with the ore from Cajati mine, providing a support to the processing through the characterization of the run of mine and products from the beneficiation plant. The mine, located in southeast Brazil, is an important national phosphate rock producer that exploits a low graded carbonatitic ore (5% P2O5). The ore essentially contains carbonates, calcite and dolomite, with variable amounts of magnetite and accessory minerals (phlogopite, olivine, pyroxene, amphiboles, serpentine, sulfides and others). The ore composition varies along the orebody, and for concentration by flotation a knowledge of these variations as a tool to the mine operation and the industrial plant optimization is necessary. A procedure using mainly standard laboratory tests supported by, chemical and mineralogical analysis was developed, in order to obtain parameters of milling behavior, mineralogical composition, liberation degree and flotation expected response. This procedure is being applied to different volumetric samples from mine bench faces, to attempt mining operations, as well as to drill core samples to achieve a technological orebody model in order to optimize the mine planning.