Selective modification of malachite with ammonium carbamate to promote flotation separation from calcite

Abstract

The malachite and calcite surfaces treated with CH6N2O2 and Na2S·9H2O featured a flotation recovery rates of 82.51% and ∼ 20%, respectively, and achieved a satisfactory selective flotation separation of malachite from calcite. CH6N2O2 could promote the formation of Cu-S on the malachite surface. A large number of Cu-S on the malachite surface resulted in increased surface roughness. However, the calcite surface remained unchanged, and S elements were not detected on its surface. CH6N2O2 could facilitate the reduction of Cu(II) on the malachite surface to Cu(I) but impeded sulfide oxidation reactions, resulting in the formation of CuS2 with higher crystallinity. The hydrated malachite surface hindered the adsorption of HS−. The activation energy of catalytic sulfidation of malachite was higher than that of direct sulfidation, indicating that NH3 can enhance the adsorption of HS−. The Cu-S chemical bond formed through the catalytic sulfidation of malachite was stronger than that formed through direct sulfidation.