Abstract: Based on the theory of flocculation-separation process， effects of modified polyacrylamide(HPM)dosage， pulp pH and stirring speed on high intensity magnetic separation of fine hematite ore were investigated by modified polyacrylamide(HPM) selective agglomeration pulp preparation-wet high intensity magnetic separation process. Scanning electron microscopy， EDS spectroscopy， Zeta potential and infrared spectrum measurements were used to study the micro-morphology of aggregates before and after magnetic separation and the change of surface properties of minerals after the action of reagents. The magnetic separation experimental results showed that， compared with the conventional high intensity magnetic separation， using selective agglomeration-high intensity magnetic separation process， the concentrate recovery of the presence of HPM in magnetic separation increases by 5.39% on condition that HPM dosage is 10g/t， pulp pH value is 10 and stirring speed is 954r/min. The apparent particle size of mineral particles in raw ore increases significantly after adding HPM and the recovery of fine hematite can be enhanced by high intensity magnetic separation with the presence of HPM. HPM can selectively flocculate hematite， and there are electrostatic adsorption and hydrogen bond adsorption on the surface of hematite， but there is no adsorption on the surface of quartz.

Key words: polyacrylamide, hematite, quartz, high intensity magnetic separation, flocculation