Enhancement And Regulation Mechanism Of Selectivity In Flocculation Flotation Of Siderite

To utilize the carbonate-bearing iron ore more efficiently,the selective flocculation flotation of micro-fine siderite is adopted to improve the iron recovery in stepped-flotation.And the regulation and enhancement mechanism of selectivity in flocculation flotation of siderite by dispersants and flocculants were investigated.More micro-fine siderite is recovered in the first stage of the stepped flotation to improve the iron recovery,and the adverse effects of micro-fine siderite on reverse flotation are reduced or eliminated.To flocculate the micro-fine selectively and improve the selectivity,the dispersion of mineral particles is necessary.The dispersion experiments of single minerals and artificial mixtures were carried out to investigate the effects of slurry conditions on the dispersion and aggregation of mineral particles.The neutral slurry condition is beneficial to the aggregation of micro-fine siderite and the detachment of micro-fine siderite from hematite and quartz.Based on the adsorption differences of dispersants on minerals,dispersants can improve the dispersion of the particles and regulate the dispersion degree of the particles.Both sodium silicate and citric acid can adsorb on hematite and quartz selectively to increase the repulsion between siderite and hematite and the repulsion between siderite and quartz.The micro-fine siderite was dispersed selectively.And the detachment of micro-fine siderite from hematite and quartz was enhanced.Based on the flocculation flotation experiments of single minerals and the selective flocculation flotation experiments of the artificial mixtures,cationic starch and pregelatinized starch were selected to realize the selective flocculation flotation of the micro-fine siderite separately.The adsorption differences of flocculants on minerals were investigated by X-ray photoelectron spectroscopy.The adjusting effects on interaction forces between mineral particles and the flocculating selectivity of the flocculants were investigated by molecular simulations and EDLVO energy analysis.The repulsion between micro-fine siderite particles,the attraction between micro-fine siderite and hematite,as well as the attraction between micro-fine siderite and quartz,decreased after cationic starch was added to the slurry.However,in the presence of cationic starch,the siderite flocs attached on the quartz because of the strong electrostatic interaction between quartz and cationic starch.The flocculating selectivity was decreased.The pregelatinized starch was adsorbed on siderite in "tail-model" by complexation.With the tail model as the preferential adsorption and the main adsorption mechanism,the flocculation of siderite was enhanced by the bridge connection of pregelatinized starch.Loop adsorption was the main mechanism that pregelatinized starch laid on hematite,which prevented the adsorption of collectors.Thus,the flotation of hematite was depressed.Based on the adsorption differences of flocculants and the differences in mineral particle size,interaction forces and surface properties of the minerals were changed.Then the selectivity regulation in flocculation of micro-fine siderite was realized by pregelatinized starch.The selectivity enhancement in flocculation flotation of the artificial mixtures with dispersants and flocculants were investigated by flotation experiments and molecular dynamics simulations.The adjustment effects of dispersants and flocculants on particle aggregation and flotation interface were illustrated by analyzing the adsorption and assembly of reagents on minerals.The selective flocculation flotation of micro-fine siderite in the first stage of stepped flotation was realized by the dispersion effect of dispersant and the selective flocculation effect of flocculants,as well as the interface adjustment effects of the two.The selectivity of the flocculation flotation was enhanced by regulating the dispersion and flocculation selectivity of micro-fine siderite in the slurry.The selectivity of siderite flocculation flotation was enhanced by citric acid and pregelatinized starch.The dispersion of micro-fine siderite was enhanced after citric acid was added.And the selective flocculation of siderite was enhanced after pregelatinized starch was added.Then,sodium oleate molecules can penetrate the adsorption layer of citric acid and pregelatinized starch and adsorb on siderite.The recovery of micro-fine siderite in the direct flotation was enhanced.Meanwhile,a dense reagent layer on hematite was formed by pregelatinized starch,and the flotation of hematite was depressed.The selective flocculation flotation of micro-fine siderite was realized.As pregelatinized starch has no influence on quartz,it has little influence on the activation of quartz in the subsequent reverse flotation.Based on the adsorption differences,the interaction energy between mineral particles and the flotation interface were regulated by citric acid and pregelatinized starch.Then the enhancement and regulation of selectivity in siderite flocculation flotation were realized.After citric acid and pregelatinized starch were used in selective flocculation flotation,the concentrate with the FeO grade of 20.15%and the FeO recovery of 55.85%can be obtained in the direct flotation,the first stage of the stepped flotation.Then reverse flotation was carried out to recover hematite from the tailings of the direct flotation.And the rougher concentrate with the TFe grade of 61.74%and the TFe recovery of 73.21%was obtained.The results of the research can provide references for improving the stepped flotation of the carbonate-bearing iron ore.