Flotation technology of middle-low-grade silica-calcia bearing phosphate rock

The invention relates to a flotation technology of a middle-low-grade silica-calcia bearing phosphate rock. The technology is implemented by the following steps that: after collophanite is processed by crushing and ore grinding until monomer separation occurs, a reverse flotation and de-magging system is used for carrying out flotation and de-magging work; desliming is carried out on rough concentrate after the flotation and de-magging process; a coarse ore particle product after desliming enters the reverse flotation and de-magging system to carry out flotation and desilicication work; and a fine ore particle product enters the reverse flotation and de-magging system again and the flotation and de-magging work is carried out on the fine ore particle product again by adding inorganic salt for condensation of fine particles and reducing the rotating speed of a flotation machine impeller. In the prior art, after desliming of the middle-low-grade silica-calcia bearing phosphate rock, lots of fine ore particles can be obtained and the grade is low; and the processed fine ore particles can not added to the concentrate or gangue directly. However, with the technology, the problem that the sludge can not be processed after the desliming work of the dual-reverse flotation process of the middle-low-grade silica-calcia bearing phosphate rock can be solved. Meanwhile, the flotation foam can be improved; the sorting feature can be improved; and the reagent dosage is reduced.