The invention relates to a process method for removing
phosphate impurities by combining gravity,
centrifugal force and flotation. By the aid of the
mineral processing flow sheet of a water-only
cyclone, a horizontal screw decanter
centrifuge and
reverse flotation, the process method includes the steps: (1) taking
phosphate ore which is
colloid phosphate and setting the content of P2O5 to range from 22% to 27%; (2)
grinding the phosphate ore to have -200 meshes larger than 75% by a wet method and setting the
solid content of ore pulp to range from 20% to 45%; (3) throwing the ore pulp into the water-only
cyclone and setting
feed pressure to range from 1.5kg / cm<2> to 2.5kg / cm<2> to obtain first-grade concentrate; (4) feeding
tailings in the water-only
cyclone into the horizontal screw decanter
centrifuge at the speed of 50-100m<3> / h, setting the speed of a rotary drum of the horizontal screw decanter
centrifuge to range from 1500r / min to 2500r / min and setting the differential speed of the rotary drum and a screw to range from 10r / min to 50r / min; (5) adding regulators into the concentrate in the horizontal screw decanter centrifuge and regulating the pH (potential of
hydrogen) value of the ore pulp to range from 4 to 5; and (6) feeding the regulated ore pulp into a flotation
machine, adding 400g / T-600g / T of
magnesium removing collectors into the regulated ore pulp, and performing inflation and defoaming to obtain second-grade concentrate. The process method has the advantages that agent consumption in a flotation process is reduced by the process method, other impurities can be removed, the grade of the phosphate is greatly improved, and the
recovery rate is also increased.