Abstract: To broaden the iron ore sources and raise the grade of ironsand for long process ironmaking system， the ball-milling and magnetic separation were conducted on a ironsand from Indonesia. The analysis methods of X-ray diffraction (XRD)， scanning electron microscopy (SEM)， and laser particle size analyzer (LPSA) were used to investigate the micro-dissociation characteristics in different ball-milling stages， the influence of particle size and magnetic induction intensity on the concentrate grade and recovery and the force mechanism of fine ironsand in the process of magnetic separation. After the ball-milling to a certain stage， the granularity of ironsand is small and the locked mineral is in the form of inclusions which is hard to continue to disintegrate. Therefore， it makes little sense to reduce the ironsand granularity for the promotion of concentrate grade. In addition， when the ore is fine， water resistance will become the main force in the process of magnetic separation and the fine particles will not be able to reach the surface of the drum， and lead to a lower concentrate recovery rate.

Key words: ironsand, dissociation, magnetic separation, fine level, force mechanism