Effect of ammonium carbamate on catalytic sulfidation and flotation of azurite

Abstract

This study aimed to investigate the effectiveness of catalytic sulfidation using ammonium carbamate and sodium sulfide to achieve satisfactory flotation recovery rates of azurite. The recovery rate of 82.51 % azurite was achieved through catalytic sulfidation. The Cu(II) and S2− species on the pure azurite surface were reduced and oxidized to Cu(I) species, Sn2− or S2− species, respectively. The analyses revealed that the rougher the azurite surface, the higher the atomic concentration of S and the more CuS2 species formed, and the more xanthate adsorption led to the formation of hydrophobic surfaces, promoting the flotation of azurite. The dissociative adsorption of H2O molecules on the (011) surface of azurite hindered further adsorption of HS− species on the (011) surface of azurite. The adsorption energy of HS− species on the (011) surface of azurite was more negative with NH3, indicating that the NH3 enhanced the adsorption of HS− species. In addition, the chemical bond strength of Cu-S formed through catalytic sulfidation of azurite was stronger than the chemical bond strength of Cu-S formed through direct sulfidation. The enhancement between S and Cu bonds greatly improved the stability of sulfide layers after catalytic sulfidation.