Selective adsorption of the activator diammonium hydrogen phosphate in the reverse flotation separation of brucite and dolomite

To achieve efficient purification of brucite resources, diammonium hydrogen phosphate (DAP) was used as an activator to realize the reverse flotation separation of brucite and dolomite in a flotation system with dodecylamine (DDA) as the collector. The microflotation test reveals only a small difference between the flotation recovery of brucite and dolomite in the DDA system. The presence of DAP considerably improve the flotation recovery of dolomite and increase the flotation difference between the two minerals. The adsorption capacity measurements indicate that DAP selectively increase the adsorption capacity of dolomite for DDA but do not affect the adsorption capacity of brucite for DDA. Contact angle measurements reveals that DAP enhances the floatability of dolomite in DDA system and the difference in contact angle between brucite and dolomite. Zeta potential detection and Fourier transform infrared spectroscopy analysis reveal that the strong adsorption of DAP on dolomite is conducive to the adsorption of DDA on the dolomite surface but the presence of DAP do not affect the weak adsorption of DDA on the brucite surface. X-ray photoelectron spectroscopy results reveal that DAP strongly adsorbs on the characteristic Ca sites on the dolomite surface and that DDA has a strong adsorption ability on dolomite after DAP adsorption, which is beneficial for the targeted activation of dolomite flotation.