Study On Behaviors And Mechanism Of Dispersion Of Hematite Fines

The influence of pH and sodium hexmetaphasphate, sodium silicate, Sodium tripolyphosphate and Sodium pyrophosphate on the dispersion of hematite fines were studied by thesedimentation experiments, surface tension and potentiodynamism mesurement in this paper. thesurface tension of solution and variation of the surface electrical property of hematite fines hadbeen studied in absence and presence of reagents. Additionally the dispersion mechanism ofsodium hexmetaphasphate, as a representative of the dispersants, on hematite fines had beenresearched by the extended DLVO theory.The results indicated that: hematite was better dispersed by sodium hydroxide comparedwith sodium carbonate;in the natural pH of distilled water, the dispersion order of fourdispersants on hematite fines is as follows: trisodium phosphate, sodium pyrophosphate> sodiumhexametaphosphate>sodium silicate. There is a synergistic action between sodium hydroxide, asa pH adjustment agent, and sodium hexametaphosphate, sodium silicate on the dispersion ofhematite fines.The transform of pH and addition of dispersants have a little effect on the surface tension ofsolution.The absolute value of dynamic potential results show that, with the increase of the pHvalue, hematite fines is Zeta potential absolute value increases; Four kinds of dispersants have asimilar affect of Zeta potential on the surface of hematite. In addition, adding dispersant willmake the point of zero charge of hematite acidic migration.The electrostatic repulsion among mineral particles was increased with the addition ofsodium hexametaphosphate, which increased the absolute value of zeta potentials of hematitefines. The space steric effects among mineral particles are also intensified due to the adsorptionof dispersant on the surface of hematite fines, then the steric repulsion among particles isenhanced.