Abstract: Ca(Ⅱ ) being the coagulant and xanthan gum being the flocculant were used in the system of selective flocculation separation of hematite from quartz,but Ca(Ⅱ ) -XG complex was formed by calcium ion and xanthan gum inevitably. The study,Ca(Ⅱ )-XG selective flocculation separation hematite from quartz,is significance for the hematite ore quality improvement. Flocculation settling tests combined with microscopic observation,Zeta potential,solution chemical calculation,and infrared spectra analysis were used to study the behavior and mechanism of Ca( Ⅱ )-XG selective flocculation separation hematite from quartz. The results of flocculation settling tests showed that the gap in settling between hematite and quartz decreased with increasing of the pH value of pulp,and the effect of Ca(Ⅱ ) on the gap in settling between hematite and quartz was insignificancy. Furthermore,the complexes made by combining xanthan gum with calcium chloride at a mass ratio of 1 ∶9 demonstrated strong selective flocculation of hematite and quartz. At pH = 2,the gap in settling rates between the two minrals was the greatest,reaching 85% and 30%,respectively. The results of microscopic observation indicated that quartz particles essentially nonflocculation whereas the hematite particles flocculated by complexes tend to form larger flocs. Zeta potential,solution chemical calculation and infrared spectra analysis showed that there was chemisorption and the electrostatic gravitational force between the complexes and hematite and quartz,in which the chemical interaction with hematite being stronger than the interaction with quartz. Based on the experimental data and analytical,a model schematic for the complexes′ selective flocculation of hematite with quartz was created. So,the selective flocculation separation of hematite from quartz can be made by changing the ratio of xanthan gum and Ca(Ⅱ ) in Ca(Ⅱ )-XG complex and the pH value of pulp,which could provide new strategy and theoretical basis for selective flocculation separation of hematite ore.

Key words: hematite,quartz,flocculants,flocculation mechanism