A new application of Cu2+ on differential modification to promote copper-molybdenum separation with a novel chalcopyrite depressant amidinothiourea

The separation of chalcopyrite and molybdenite has always been a challenge in mineral processing because of their similar floatability and close association. This study proposes a new chalcopyrite depressant named amidinothiourea (ADT) and a new application of Cu2+ on differentially modifying chalcopyrite and molybdenite. It is found that small dosage of ADT is insufficient to depress chalcopyrite, although there is ADT adsorption on chalcopyrite surface at this time. While after Cu2+ modification on chalcopyrite and molybdenite, a small dosage of ADT can strongly depress chalcopyrite, and has no effect on molybdenite. The largest difference of grade and recovery between chalcopyrite and molybdenite were 45.32 and 70.79 % in mixed-mineral flotation with 2.0 × 10−4 mol/L of Cu2+ and 1.6 × 10−4 mol/L of ADT. The mechanisms of ADT depression and Cu2+ modification were investigated through LEIS, XPS, ToF-SIMS and ICP-OES tests. LEIS experiments show that ADT can adsorb on chalcopyrite surface, and particularly pronounced after the modification of Cu2+ on chalcopyrite. XPS and ToF-SIMS confirm that N is the site of action for ADT, and Cu is the site of action for minerals. XPS, ToF-SIMS and ICP-OES tests reveal that Cu2+ modifies chalcopyrite by promoting the dissolution of iron ions and firmly binding with the exposed unsaturated S. While Cu2+ modifies molybdenite by binding with saturated S atoms weakly.