PH-controlled dispersion of micro-fine siderite from hematite and quartz

Abstract

To reduce the heterocoagulation of siderite with hematite and quartz, the controlled dispersion of micro-fine siderite was investigated at different pH values. The dispersion ratio, particle size distribution (PSD) and supernatant turbidity of suspension, and the direct flotation index were used to characterize the pH-controlled dispersion. Based on the lower dispersion ratio (ca. 40%) of the micro-fine siderite and the smallest difference between the experimental and ideal turbidities of the mixed suspension, micro-fine siderite homocoagulation was sustained at an approximate pH of 7, under which heterocoagulation was suppressed. Therefore, the controlled dispersion of the micro-fine siderite could be realized under a neutral condition. DLVO calculations revealed that the total interaction energy between the micro-fine siderite and the other two minerals tended to zero at pH of 7. However, at other pH values involving either a repulsive or attractive DLVO energy, the heterocoagulation between micro-fine siderite and the other two minerals was accelerated. A preferable controlled dispersion of micro-fine siderite can be achieved by maintaining a neutral condition at DLVO energies close to zero. The direct flotation of siderite revealed that a concentrate with FeO content of 16.31% and FeO recovery of 61.57% was recovered at a pH of 6.8. The greatest difference between FeO recovery and TFe recovery was 24.04%, indicating the suppressed heterocoagulation. Therefore, a neutral condition is favorable for the controlled dispersion of siderite from hematite and quartz.