Investigations of amino trimethylene phosphonic acid as a green and efficient depressant for the flotation separation of apatite from calcite

Flotation separation of apatite from calcite is difficult due to their same activate calcium atoms on the surface. To address this issue, amino trimethylene phosphonic acid (ATMP) was introduced to separate apatite and calcite in this research. The micmflotation results showed that NaOl had an excellent collecting ability to apatite and calcite. Meanwhile, the tests also found that ATMP had a strong depression ability to calcite, but it hardly influenced the apatite floatability. The artificial mixed minerals flotation results confirmed that ATMP could be used as a depressant to separate apatite and calcite in the presence of NaOl. Zeta potential measurements illustrated that the addition of ATMP prevented the NaOl adsorption onto the calcite surface, while it hardly affected the interaction of NaOl with the apatite surface. Solution chemistry calculation of ATMP was conducted to reveal the main species of ATMP, while XPS analysis further indicated the strong chemisorption of ATMP onto calcite rather than apatite. Hence, the selective depression ability of ATMP was attributed to the electrostatic repulsion and steric resistance for the apatite surface and the stable adsorption structure at the calcite surface.