Hydroxamic Acid Collector Synthesis And Ilmenite Flotation Performance

The development of colloctors with high efficiency, low cost and low toxicity is not only the key to flotation of ilmenit, but also the significance for the exploitation of mineral resources. The thesis stems from the National 973 Program "molecular assembly and synthesis of high efficiency collectors for difficult processing ores" (No. 2007CB613602-3).In this paper, a series of hydroximic acid collertors, including tert-butyl benzoic hydroximic acid, octanoic hydroximic acid, benzoic hydroximic acid and salicylic hydroximic acid, were prepared after searching and optimizing. For tert-butyl benzoic hydroximic acid, the results majorized as follow:alcohol-acid ratio was regulated at 4.5; the DBSA of 15% acid in mole as catalyst was introduced into the system and then esterificated for 10 h; the hydroxylamine hydrochloride was reacted with sodium hydroxide on condition that the ratio of equivalent ester, hydroxylamine hydrochloride and sodium hydroxide was 1:1.2:2.2; the mass ratio of water and alcohol in the hydroximation solvent was regulated at 5; without any purification, direct hydroximation sustained for 4 hours at the temperature of 50℃and the total conversion of 82.83% can be achieved. The hydroximic acids synthetized through improved process can be uesd as collectors derectly.The monomineral experiments of ilmenite, calcite, dolomite and quartz present that the tert-butyl benzoic hydroximic acid and octanoic hydroximic acid collectors exhibit strong flotation capability on ilmenite while the benzoic hydroximic acid and salicylic hydroximic acid exhibit weak. The recovery of ilmenite is 75% under the condition that the concentration of octanoic hydroximic acid is 200 mg/L, and the recovery can preserve over 90% when the concentration of tert-butyl benzoic hydroximic acid reaches 300 mg/L. Therefore both of collectors are available to separate ilmenite from quartz. Accordingly, the actual mineral experiment of ilmenite form Panzhihua show that the hydroximic acids synthetized through improved process exhibit better results than pure collectors including oleic acid, hydroximic acids, oxidation paraffin soap and so on. Furthermore, using the tert-butyl benzoic hydroximic acid or octanoic hydroximic acid collectors can obtain a recovery of 84% with a content of 36% going by a roughing flotation.The adsorption mechanism of the hydroximic acids on ilmenite has been investigated through Zeta-potential, IR spectrum measurements, surface electrical and solution chemical analysis. Zeta-potential and IR spectrum measurements confirm that the interaction between hydroximic acid collertors and ilmenit must be the chemical action.