Mechanism of Cu Ion Targeting Combined with an Organic Depressant To Enhance the Flotation Depression of Pyrite

In this study, pyrite was used as the research object, and the behavior and mechanism of a copper-ion-enhanced organic depressant in depressing pyrite flotation were studied. Microflotation experiments showed that, after the addition of CuSO₄ and N,N-dimethyldithiocarbamate (N,N-DDS), the floating collection efficiency of pyrite declined from 82.37 to 21.03% at pH 8.5. Infrared spectroscopy studies indicated that the addition of CuSO₄ caused a significant enhancement in the characteristic N,N-DDS peaks on the pyrite surface. X-ray photoelectron spectroscopy (XPS) revealed that, following the addition of CuSO₄ and N,N-DDS, the relative atomic concentration of N 1s considerably enhanced on the surface of pyrite, with N 1s derived from N,N-DDS. Time-of-flight secondary ion mass spectrometry showed that, before and after the addition of CuSO₄, the normalized peak values of CSN^– on the pyrite superficial layer were 0.0116 and 0.0032, respectively. All of the above-mentioned results indicate that the Cu ion promotes the adsorption of N,N-DDS on pyrite and facilitates the formation of complex ((CH₃)₂NCSS)₂Cu. The N and S atoms in −NCS and metal ions formed chemical bonds, which were the primary mechanism of the interaction between N,N-DDS and pyrite. This process reduces the floatability of pyrite and achieves the selective depression of pyrite.