Selective flotation separation of smithsonite from calcite by application of amino trimethylene phosphonic acid as depressant

Amino trimethylene phosphonic acid (ATMP), an eco-friendly reagent widely applied in industrial production, was employed as a depressant for flotation separation of smithsonite from calcite for the first time. Microflotation test results show that ATMP exhibits selective inhibition effect on calcite flotation. Calcite and smithsonite can be well separated in flotation process by applying ATMP as the depressant and sodium oleate (NaOL) as the collector. Based on a series of measurements including zeta potential, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR), it is found that large amounts of ATMP can be chemically absorbed on the surface of calcite by chelating with surface Ca2+ sites and thus inhibiting the adsorption of NaOL. While, in comparison, much less adsorption of ATMP is taken place on the surface of smithsonite and hardly affects further adsorption of NaOL. Atomic force microscopy (AFM) images of calcite after treated with ATMP indicate that almost the whole surface of calcite is covered with the dense agglomerate adsorption layer. All in all, these results present excellently selective depression ability of ATMP on smithsonite-calcite flotation separation process.