Abstract: An amphiprotic collector DA-1 synthesized by Northeastern University was used to float the mixed magnetic concentrate of Qidashan dressing plant in Anshan Iron and Steel Company. The optimal rougher floatation condition is flotation temperature 20℃，pH of pulp 11.5，dosage of DA-1 600 g/t，and dosage of depressor gelatinization starch 600 g/t. At appropriate technical conditions，a closed circuit flotation flowsheet of single-stage roughing，two-stage scavenging，and middles returning was adopted to handle a mixed magnetic concentrate with Fe 42.92%. A concentrate of Fe concentrate grade 67.31% and recovery 87.90% was obtained.

Key words: Amphiprotic collector, DA-1, Reverse flotation