Abstract: In order to solve the long-standing problems of pump blockage，pipeline siltation，liquid level out of control，flow fluctuation and reagent splashing in the CaO reagent addition link of anion re⁃ verse flotation system of a micro-fine complex refractory magnetite-hematite mixed iron ore，a set of flota⁃ tion reagent continuous addition and precise control technology integrating precision filtration，liquid level stability control and flow quantification is developed.The technology takes plane linear sieve precision fil⁃ tration，ultrasonic-PLC high and low liquid level linkage alarm，stable pressure overflow and reflux quan⁃ titative addition as the three core devices，and realizes the continuous，stable and accurate quantitative transportation of CaO without blockage and overflow.The industrial application results show that the tech⁃ nology can completely eliminate the pump shaft fracture，pipeline blockage，reagent interruption，overflow and other stubborn problems，stabilize the anionic reverse flotation process index，significantly improve the iron concentrate grade and metal recovery rate，reduce the loss of metallurgical mining equipment and operation and maintenance strength，meet the requirements of 24 h continuous and efficient production of large open-pit iron ore，and provide engineering demonstration for the precise control of reverse flotation reagents for similar micro-fine refractory iron ore.

Key words: micro-fine iron ore, hematite-magnetite mixed ore, anionic reverse flotation, reagent continuous addition, precise control, plane linear sieve