Study On Settling Performance And Floc Characteristics Of Fine Hematite Concentrate

To solve the problems of long settling time and low settling rate in the concentrated stage of fine-grained hematite concentrate,four different molecular weight anionic polyacrylamides(APAM)were selected as flocculants in this paper,and the performance was characterized by settling velocity,supernatant turbidity and unit settling area by static settling test method,combined with EDLVO theory for theoretical explanation to explore the different influencing factors on the settling performance The flocs were monitored in situ by real-time particle microscopic monitoring(PVM),and the flocs were characterized by their microscopic morphology,relative backscattering index(RBI),fractal dimension,porosity and equivalent diameter to investigate the floc characteristics under different conditions.The results of the sedimentation performance study showed that: the increase in molecular weight and amount of flocculant did not consistently improve the sedimentation performance;the sedimentation performance of fine-grained hematite concentrate gradually decreased with the increase in slurry concentration and flocculant solution concentration;except for the turbidity of supernatant,the sedimentation performance was inhibited under acidic conditions and improved under alkaline conditions;the appropriate slurry temperature and cation concentration would improve the sedimentation performance,while too low or The appropriate slurry temperature and cation concentration will improve the settling performance,while too low or too high temperature and concentration will deteriorate the settling effect.Based on EDLVO theory,the influence of flocculant dosage and cation concentration on the settling performance is explained theoretically,the repulsive potential energy increases with the increase of flocculant dosage,and when the flocculant is excessive,the excessive repulsive force is not conducive to settling;the repulsive potential energy decreases with the increase of cation concentration,and when the cation concentration is too high,it will be unfavorable to the action of flocculant and deteriorate the settling effect.The results of floc characteristics show that: the volume and RBI of floc microform increase with the increase of molecular weight of flocculant and the increase of settling time;the fractal dimension of floc decreases with the increase of molecular weight of flocculant,and the trend of increase and decrease with the increase of flocculant dosage and concentration of different valence cations;the porosity of floc increases with the increase of molecular weight of flocculant,and the porosity of floc increases with the increase of flocculant dosage and concentration of different valence cations.The equivalent diameter of flocs increases with the increase of flocculant molecular weight and flocculant concentration,and the fractal dimension of flocs gradually decreases with the increase of different valence cation concentration.