Study On The Mechanism And Application Of Effective Reagent For Reverse Flotation Of Iron Ores

The removal of silica to produce pure iron concentrates is a dominant way for iron-ore dressing at present. In order to solve the problems, such as bad selectivity, sticky bubbles, weak collectability at low temperature by using fatty amines to fulfil the reverse flotation of iron ore in a iron Mine in AnShan. This study was to find a new cationic collector with better selectivity and collectability than alkyl amine to realize the selective flotation of silica from the iron ore.A series of flotation tests using new cationic collectors (CS1?CS2? CS3?CS4?) and the combined collectors (CS3:CS1=3 & CS3:CS2=2) and same normal cationic collectors on quartz, magnetite and specularite and iron ores have been carried out, such as the flotation of pure minerals, the flotation separation of mixtures, the batch and pilot flotation tests on iron ores. The mechanism of the interaction between the reagents and minerals was also studied.In the pH range of 6~12, the results of the flotation tests indicate that the performance of the new combined cationic collector (CS3:CS1=3) and (CS3:CS2=2) is similar, and they are effective collectors for reverse flotation of the iron ores. The combined cationic collectors exhibited the same collectability as dodecylamine, but better selectivity than dodecylamine. By using the combined collector, the dosage of the collector decreased from 1 10-4mol/L to 1 x 10-5mol/L .The magnetite and specularite was depressed by using quebracho as the depressant of the iron minerals.The combined collecror(CS3:CS2=2) was successfully applied to separate quartz from magnetite by reverse flotation. A concentrate with a grade of 67.58% TFe and the recovery of 98.46% TFe was yielded from a feed with a grade of 57.69% TFe and 23.17% SiO2. The separation of quartz from specularite was achieved by the addition of quebracho as iron mineral's depressant. A concentrate with a grade of 67.69% TFe and therecovery of 76.61% TFe was obtained from a feed with a grade of 55.34% TFe and 22.74% SiO2.The reverse flotation tests on the magnetic concentrate have also shown that the recovery of Fe in the concentrate increased 8.32% at the similar concentrate grade by using the new combination collectors (CS3:CS2=2) as dodecylamine. And a concentrate with a grade of 68.57% TFe and the recovery of 97.18% TFe was also obtained from a feed with a grade of 63.68% TFe in the pilot tests.The modern measurement techniques, such as contact angle, Zeta-potential, adsorption determination and FT-IR measurements, were used to reveal the action mechamism of the combined collectors and the depressants on the minerals.The results showed that the new combined collectors absorb on the quartz surface prior to the surfaces of magnetite and specularite, and change the contact angles and the Zeta potentials of quartz more markedly than the magnetite and specularite, and these are probably the reasons for the differences of hydrophobicity of the quartz and the iron minerals, and confirm the reverse flotation separation of quartz from the iron minerals on the basis of flotation theories. At the same time, the results of FT-IR measurements also proved that the . adsorption of combined collector on the surface of minerals is reversible, physical type because there was no new products on the surface of the minerals. The addition of quebracho increased the hydrophilicity of the iron minerals, and changed their zeta potentials markedly, and improved the reverse flotation separation of quartz from specularite.There are about 50000 words, 49 figures, 9 tables and 91 references.