Exploration of a novel depressant pullulan gum for the flotation separation of specularite from aegirite

Abstract

The successful separation of specularite and aegirite in the flotation process heavily relies on efficient depressants due to their closely similar physical and chemical properties. This study focuses on investigating the specific depressive impact and mechanism of pullulan gum (PG) on specularite and aegirite. The findings from single mineral flotation tests revealed the maximum floatability difference was 49.7 percentage point when pH was 8 and the dosage of PG and DDA were 90 mg/L and 30 mg/L respectively, which indicated that PG selectively depressed specularite while displaying a notably weaker depression effect on aegirite. The selective depressive impact of PG was further affirmed through artificial mineral mixed mineral flotation tests. Additionally, results derived from contact angle measurement, adsorption capacity measurement, Zeta potential measurement, and FT-IR analysis collectively highlighted the significantly higher affinity of PG to the surface of specularite compared to aegirite. This stronger interaction between PG and specularite obstructed the adsorption of DDA onto the latter mineral. Moreover, XPS analysis provided insights indicating that PG chemically adsorbs onto the specularite surface, forming a Fe-O complex via a potential reaction between OH and Fe site. As a result of these comprehensive findings, PG emerges as a promising novel depressant for effectively separating specularite from aegirite.