| Oolitic hematite widely distributed and largely reserved in China, but sofar has not been able to take utilization of this resource due to the complexstructure of such iron ore. In the past few years, the domestic demand for ironore continuously rise, and the situation was still heavily dependent on importsof iron ore resources from other countries. Thus exploration of beneficiationtechnology to sort oolitic hematite has great significance for the mitigation oftensions between supply and demand of iron ore.Study of mineralogy indicates that: Sedimentary oolitic hematite usuallycontains a large amount of argillaceous fraction, And iron mineralsdisseminated in a fine granularity at20microns or less in order to achievemonomer dissociation. Hematite and gangue minerals quartz, calcite, illiteand chlorite form a symbiotic relationship, Therefore, the conventionalseparation methods are difficult to achieve satisfactory results. Research onoolitic hematite in western Hubei via a series of sorting test (includingselective flocculation, high intensity magnetic separation, reverse flotation),and the best condition was determined as follows: selective flocculation, highintensity magnetic separation (the magnetic field strength is1.52×106A/m),cation-anion double reverse flotation (anionic reverse flotation rougher:NaOH with the consumption of900g/t, starch850g/t CaO530g/t, TS-02650g/t, cleaner TS-02300g/t; the value of pH was controlled about9.5in cationicreverse flotation, rougher: collector DDA500g/t, cleaner: DDA100g/t), andthen the final concentrate with the grade of54.54%and total recovery of69.09%was obtained from the iron ore with the grade of43.42%. Tailings:Magnetic tailings24.34%, anionic reverse flotation tailings31.50%, Cationicreverse flotation tailings36.93%.Take the concentrate and flotation ore (magnetic concentrate) into X-ray fluorescence spectroscopy, and the analysis results show that: the content ofsilicon and phosphorus reduce in a certain degree (silicon: decrease from9.97%to6.43%, phosphorus: reduce to0.347%from1.18%), however, thereis little difference between them in the content of aluminum. Therefore thechoice of cationic collector should make appropriate adjustments in furtherstudy.Explore adhesion mechanism of flotation reagent and change of potentialon the surface of mineral after adhesion by collector via infrared spectroscopyand electric potential test. The test elaborately analyze the adhesionmechanism of sodium oleate and quartz, starch and hematite, and the effect ofpH value on Zeta potential of minerals in solution with different volume ofcollector. Finally, guide the actual flotation tests effectively.Through analysis of the infrared spectra, Mechanism of sodium oleate onquartz determines as follows: after the adsorption of Calcium ions thathappened on the hydroxylated silica surface, Sodium oleate adsorbed on thesilica surface by generating calcium carboxylate to achieve the purpose ofadhesion to the mineral surface. Effect of starch and hematite, may determineby molecular structure of the starch with a large number of hydrophilic groups-hydroxy mainly form hydrogen bonds between the surface of hematite afteradsorption, while other polar groups that point to pulp increase thehydrophilicity of hematite.The electric potential results show that: adsorption of flotation agent caneffect mineral particle surface electric potential with a phenomenon of offseton different levels. Quartz positively charged when the pH<PZC, anioniccollector sodium oleate adsorbs on the surface of quartz via electrostaticinteraction which results in a negative offset. And quartz charged negativelywhen the pH>PZC, but the negative offset still happened on Zeta potential.wecan conclude that adhesion mechanism can’t be the result of static electricity,but should be considered as a process of chemical adsorption inthis circumstance. When cationic collector DDA and the surface of diasporecharge differently, due to the presence of electrostatic attraction, making theDDA adsorbed to mineral particles and caused the change on the electricpotential. but the reason why DDA still change the potential when diasporeparticle charged positively should attribute to molecular adsorption instead ofelectrostatic interaction. After adsorption of starch on hematite particlesurface, the tendency of charging negatively is more evident, and thinks tothis electrostatic repulsion effect, resulting in disadsorption between them inanionic reverse flotation.According to the test results we can initially conclude that characteristicsof oolitic hematite determine its representative refractory position accepted bynation and internation. Final beneficiation index obtained through a series ofseparation processing oolitic hematite in western Hubei: the grade of iron oreincrease from43.42%to54.54%with the total recovery of69.09%. |
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