Selective adsorption of Na2ATP as an eco-friendly depressant on the calcite surface for effective flotation separation of cassiterite from calcite

Adenosine 5 '-triphosphate disodium salt (Na2ATP) was used as the efficient depressant for the separation of cassiterite from calcite. The effect of Na2ATP on the flotation of cassiterite and calcite was evaluated by the micro-flotation experiments, and the results showed that an excellent separation performance was achieved at the reagents regime of 1.0 mM Na2ATP and 0.14 mM NaOL when pulp pH was 9.11. Moreover, the adsorption and depression mechanism of Na2ATP on calcite was investigated via a series of surface analyses. The contact angle analysis and zeta potential measurements showed that Na2ATP was strongly adsorbed onto the calcite surface rather than cassiterite surface, and that could still significantly enhance the hydrophilicity of the calcite after conditioned with NaOL. The FTIR analysis and XPS analysis results indicated that the interaction between Na2ATP and calcite was the chemical binding, and the calcium atom on the calcite surface and the phosphate group of Na2ATP was the major reaction unit in this processing. Furthermore, the pre-adsorption of Na2ATP on calcite surface would impede the interaction between NaOL and calcite, but the adsorption of NaOL on cassiterite surface could not be affected by the weak physical adsorption of Na2ATP. Therefore, Na2ATP could be utilized as a potential depressant for removing calcite from cassiterite.