Review of the Mechanism for Orfom<sup>®</sup> D8 Depression of Chalcopyrite in Cu-Mo Separation during Cleaner Flotation

For the past 5 years, Montana Tech has coordinated eff orts with Chevron Phillips Chemical to determine how organic depressant, disodium carboxymethyl trithiocarbonate (Orfom® D8 depressant), works separate chalcopyrite from molybdenite during cleaner flotation of a bulk sulfide concentrate. Pure minerals were studied by cyclic voltammetry, X-ray photoelectron spectroscopy, Fourier transform infrared zeta potential and adsorption density. Results illustrated that Orfom® was specific for chemisorbing electrochemically through its thiol functionality (CSS-) thereby allowing carboxylate group (COO-) extend into solution cause depression. Density Function Theory via molecular orbital modeling corroborated results. Flotation results obtained using laboratory simple kinetic tests (SKT), bench-scale experiments, industrial plant trials revealed grade recovery both Cu Mo better than those most common inorganic NaSH. Replacing NaSH in Cu-Mo is therefore recommended would simultaneously address mining sustainability issues.