Process for reducing collophanite flotation tailing grade

The invention discloses a process for reducing the collophanite flotation tailing grade. The process comprises the specific steps that firstly, mineral is ground, then the ground mineral products are graded, relatively coarse grained products obtained after grading are returned to a mill to be ground again, and the relatively fine grained products obtained after grading enter the flotation process to be subjected to reverse flotation operation; flotation foam products serve as final tailings, and products in a flotation cell are graded; relatively coarse grained products obtained after grading serve as intermediate products and are returned to the mill to be ground again, a closed-loop operation is formed, and relatively fine grained products obtained after grading serve as final fine mineral products. The high-magnesia collophanite is processed through the process, qualified phosphate concentrate with the MgO grade smaller than or equal to 0.8% is obtained, the recovery rate of concentrate is improved by 1-3%, and the tailing P2O5 grade is reduced by 1-2%. The stable collophanite flotation technical-economic indexes can be obtained through the process, the utilization rate of the phosphate rock resources is improved, the energy and chemical consumption of a whole flotation mill are reduced, the economic and social benefits of the flotation mill are improved, and the process has wide industrial popularization value.