Synthesis And Flotation Performance Of C₈ Hydroxamic Acids

Collectors play an important role in the flotation of ilmenite, and hydroximic acids have good selectivity and collecting capability for ilmenite. Thus, the development of novel, high efficient and green colloctors, and the study of action mechanism between collector and minerals, are of great significant for the economical utilization of ilmenite.Three hydroximic acids,including 2-ethyl-2-hexenoic hydroximic acid, isooctyl hydroximic acid, octyl hydroximic acid, were prepared respectively esterification and hydroxyl-oximation reaction using 2-ethyl-2-hexenoic acid,2-ethylhexanoic acid and cprilyci acid as raw material. The effect of acid-alcohol mole ratio, dosage of H2SO4, reaction temperature and reaction time on esterification reaction conversion rate were studied. The optimal esterification synthetic conditions were as following:alcohol-acid mole ratio was 3:1-6:1, dosage of H2SO4 was 0.028-0.037 of per-mole fatty acid, reaction temperature was 80 ?, and reaction time was 6 hours. The esterification reaction conversion rate of 94% was obtained. The effect of volume fraction of water, reaction temperature and reaction time on hydroxyl-oximation reaction conversion rate were studied. The optimal hydroxyl-oximation reaction conditions were as following:volume fraction of water was 15%?75%, reaction time was 3 hours, and reaction temperature was 50 ?. The hydroxyl-oximation conversion rate of 70% was obtained.The single mineral flotation experiments of ilmenite, calcite and quartz showed that the collecting ability of the three collectors followed the order as:2-ethyl-2-hexenoic hydroximic acid> octyl hydroximic acid> isooctyl hydroximic acid. At pH 9 and collector concentrations 250 mg/L, the flotation recoveries of ilmenite was about 84% for 2-ethyl-2-hexenoic hydroximic acid, whereas, only about 80% for octanoic hydroximic acid and below 40% for isooctyl hydroximic acid, respectively. The bench-scale flotation tests showed that a rougher concentrates with 32% TiO2 could be obtained by using 2-ethyl-2-hexenoic hydroximic acid as collector, and the flotation recovery of TiO2 was 84%.The adsorption mechanism of the hydroximic acids on ilmenite was investigated through Zeta-potential, IR spectrum measurements, surface electrical and solution chemical analysis. Zeta-potential and IR spectrum measurements confirmed that the interaction between hydroximic acid collertors and ilmenit might be the chemical action.