Exploration of an eco-friendly depressant 2-hydroxyphosphonylacetic acid for the flotation separation of barite from calcite

This work evaluated the 2-hydroxyphosphonylacetic acid (HPAA) as a depressant for calcite in barite flotation when using sodium oleate (NaOl) as a collector. Micro-flotation results presented good recoveries of barite and calcite could be obtained using the individual NaOl, and the presence of HPAA selectively depressed the calcite flotation while did not affect the barite flotation. Barite/calite minerals mixture flotation verified that the addition of HPAA realized the high separation efficiency between barite and calcite. Zeta potential results revealed that NaOl collector adsorbed onto the HPAA treated barite surface while it did not interact with the HPAA treated calcite surface. The XPS analysis demonstrated that the groups of carboxyl and phosphate groups (in HPAA molecular) chelated with Ca sites of the calcite surface by chemical bonding while the adsorption strength of HPAA onto the barite surface was very weak, and the computational chemistry also indicated that the adsorption energy of HPAA onto barite surface was weaker than that of onto calcite surface. Hence, HPAA could be used as a potential inhibitor for calcite depression while allowing the flotation of barite.