New insight into enhancing sulfurization of azurite with ethylenediamine and its response to xanthate adsorption

Abstract

Organic amine salt is an efficient sulfurization accelerator for copper oxide minerals. In fact, its underlying function mechanism is scarce. In this study, the evolution of sulfurized products of azurite under ethylenediamine (EDA) regulation and its response to the xanthate adsorption and surface hydrophobicity were investigated. ToF-SIMS, ICP-OES, XPS and total nitrogen analyses showed that pretreatment with EDA promoted the additional formation of copper sulfide products on azurite, and the sulfurization efficiency increased by 17%. The solution chemistry and transition state search analyses revealed that EDA changed the sulfurization reaction pathway by the formation of copper ethylenediamine ion (Cu(en)n2+, n = 1, 2) resulting in the increase of the reaction energy barrier from 55.12 kcal/mol to 197.83 kcal/mol. Therefore, the deposition rate of copper sulfide on azurite was slowed down, thus creating stable solution environment for the dense adhesion of products, which was observed by FESEM. The increasing copper sulfide products created favorable conditions for the stable adsorption of SBX on azurite, ultimately improving the surface hydrophobicity of azurite. These results may provide a deeper understanding for EDA promoting the sulfurization of copper oxide minerals.