Activation-inhibition mechanism of diammonium hydrogen phosphate in flotation separation of brucite and calcite

In this study, we employed diammonium hydrogen phosphate (DHP) to regulate the flotation separation of brucite and calcite. Further, we investigated the activation and inhibition effects of DHP on calcite flotation and brucite flotation, respectively. The flotation test demonstrated that DHP enhances and reduces the floatability of calcite and brucite, respectively, resulting in a recovery difference of 77.54% with respect to the flotation separation of the two minerals. Contact angle measurements provided further evidence of the impact of DHP; it increases the contact angle and improves the floatability of calcite while decreasing the contact angle and reducing the floatability of brucite. Zeta potential analysis indicated that DHP can substantially reduce the adsorption of dodecylamine (DDA) on the surface of brucite but has little effect on the adsorption of DDA on the surface of calcite. Infrared analysis revealed that the adsorption of DHP on the surface of calcite benefits the collection of calcite using DDA, while its adsorption on the surface of brucite can hinder the collection of brucite by DDA. The X-ray photoelectron spectroscopy test demonstrated that DHP has a stronger affinity for the calcite surface than the brucite surface, and its adsorption effect on the calcite surface is more intensity.