Synthesis Technology Of Hydroxamic Acid Collectors By Hydroxylamine Method And Its Flotation Performance

Hydroximic acid is a kind of oxide minerals flotation collector with excellent collecting ability and selectivity. A series of hydroximic acid collectors were prepared by hydroxylamine method, including octyl-hydroximic acid, decyl-hydroximic acid, lauryl-hydroximic acid and salicyl-hydroximic acid. The flotation capability of the different hydroximic acid collectors on ilmenite, albite and potash feldsparthe were studied. The function mechanism of hydroximic acid collectors on ilmenite were studied through the surface tension, adsorption amount, Zeta-potential and IR spectrum measurements.With octanoic acid, decanoic acid, lauric acid and salicylic acid as stocks were conducted respectively esterification and hydroxyl-oximation reaction with methanol and hydroxylamine. The effection on conversion rate of acid-alcohol volume ratio, dosage of H2SO4, dosage of benzene, water-alcohol volume ratio, dosage of hydroxylamine hydrochloride, reaction temperature and reaction time were studied. The optimal esterification synthetic process were as follow:acid-alcohol volume ratio3:1～2:1, dosage of H2SO40.37:1～1.13:1, dosage of benzene0.07:1～0.13:1, reaction temperature80℃, reaction time2～5hours. The optimal hydroxyl-oximation reaction synthetic process were as follow: water-alcohol volume ratio5:1～2:1, the ratio of equivalent ester, hydroxylamine hydrochloride and sodium hydroxide was1:1.1:2.2, reaction time3hours, reaction temperature50℃. Based on fatty acid, The esterification and hydroxyl-oximation reaction conversion rate of85%can be obtained.The results of single mineral flotation experiments showed that octyl-hydroximic acid, decyl-hydroximic acid and lauryl-hydroximic acid have excellent flotation performance and selectivity on ilmenite. Under the condition of the dosage of collectors300mg/L or so, the pH value of flotation system6～8, it can obtain more than85%recovery for ilmenite. The flotation recovery of salicyl-hydroximic acid on ilmenite, albite and potash feldspar were less than20%. The result of actual mineral flotation experiment on ilmenite showed that octyl-hydroximic acid, decyl- hydroximic acid and lauryl-hydroximic acid have excellent flotation performance, can obtain around40%for the grade of ilmenite concentrates and around90%recovery rate.The result of the surface tension and adsorption amount showed that, with the increase of the length of carbon chain, CMC gradually reduced and the flotation performance increase gradually. The result of zeta-potential and IR spectrum measurements showed that the interaction between hydroximic acid collectors and ilmenite must mainly be chemical adsorption, partly physical adsorption.