Study On Flotation Of A Low Grade Phosphate Ore In Brazil By Using Mixed Collectors

With the exploitation of phosphate resources, most rich ore resources are firstlyexploited, and the percentage of rest poor low-grade and refractory ores is higher andhigher. To meet the rising demand of phosphorus caused by economic growth andsocial development, the exploitation and utilization of mid and low grade phosphaterocks are imminent. Nowadays, the domestic and foreign beneficiation studies on midand low grade phosphate ores mainly focus on flotation, and the development of newefficient reagents is one of the significant directions of flotation research forphosphate ores. A phosphate ore in Brazil has low P2O5grade and high content ofharmful impurities, and the performance of traditional fatty acid collectors used in itsflotation was poor. The P2O5recovery of concentrate was only55~58%. This paperwas carried out to solve these problems. A mixed collector MGS was developed bycombined using of reagents to improve P2O5recovery and systematic beneficiationtests were conducted to determine an appropriate process and an optimum reagentsystem. In addition, the flotation mechanism of MGS was studied through pureminerals flotation tests， Zeta-potential measurements and Infrared AbsorptionSpectrum analysis in this paper.The XRD analysis and chemical elements analysis show that it belongs to a lowgrade silicate-carbonate phosphate ore with apatite as target mineral and quartz,hematite, dolomite, magnetite as main gangue minerals. The grade of P2O5is only15.21%, while the contents of SiO2and Fe2O3are higher (21.83%and18.36%,respectively). The content of MgO is4.83%as well.The tests of collectors’ selection and proportion indicate that the flotation effectof this phosphate ore is poor when using MG-2alone, but the addition of an anionicsurfactant SF can obviously improve the flotation effect. The mixed collector MGSwhich has the best performance is obtained from MG-2compounding with SF as theratio of7.5:2.5.The optimum process and reagent system are ascertained through flotationprocess tests. After a closed-circuit process of one roughing, two concentrations andone scavenging, the concentrate can obtain P2O531.58%with a yield of37.02%, arecovery of78.83%, and the content of SiO2, Fe2O3and MgO reduces to6.97%,0.24% and3.83%respectively. The results show that MGS is an efficient collector at roomtemperature and has good separation effect for this phosphate ore. Compared to theoriginal index of industrial production, MGS makes the recovery of P2O5increase bymore than20%to achieve an efficient recovery of phosphorus and reach the researchtarget.The pure mineral flotation tests show that MGS has stronger collecting abilityand greater capacities for anti-interference of Ca2+, Fe3+，as well as a betterperformance at low temperature than MG-2during its action with apatite. Themeasurements of Zeta potential show that the adsorption of MGS on apatite surface isstronger than that of MG-2since the change of Zeta potential is bigger after the actionof MGS with apatite. Infrared spectrum analysis indicate that the adsorption form ofthe mixed collector MGS on apatite’s surface may be that SF preferentially adsorbson apatite’s surface, and then a second stacked adsorption by MG-2occurs on thesurface of which properties has changed.