The application provides a
copper-iron
mineral flotation inhibitor and a preparation method thereof, which comprises the following steps: adding water, o-
aminobenzoic acid and
hydrochloric acid into a reaction kettle, controlling the temperature in the reaction kettle to be 2-6 DEG C; adding
sodium nitrite and
sodium sulfite solution into the reaction kettle in sequence to carry out reaction; after the reaction is completed, the temperature in the reaction kettle is increased to 120-180 DEG C to continue the reaction for a predetermined time; after the reaction is completed, the temperature in the reaction kettle is decreased to 40-60 DEG C,
tannic acid is added to carry out reaction, and finally the temperature is cooled to normal temperature, so the
copper-iron
mineral flotation inhibitor is obtained. The
copper-iron
mineral flotation inhibitor prepared by the application can be used as the inhibitor of copper-iron minerals in
molybdenum ore and copper-
molybdenum ore flotation, can effectively inhibit the
copper sulfide mineral and the
iron sulfide mineral, has the characteristics of small dosage and high efficiency of
molybdenum mineral flotation under low
alkalinity condition, and is convenient to control, has no by-product in the preparation process, and will not cause environmental
pollution in production.