Interface adsorption mechanism of the improved flotation of fine pyrite by hydrophobic flocculation

• Fine pyrite (−26 μm) flotation was improved by combined use of two reagents. • Particle size of fine pyrite was flocculated to a value suitable for flotation. • Amidation of two reagents caused hydrophobic and flocculation of fine pyrite. • Reticulated polymeric hydrophobic product may generate on the surface. Hydrophobic flocculation is one of the effective method to solve the fine flotation. In this paper the hydrophobization and flotation performance of coco-alcyl-amine-acetate (C-1) on fine pyrite (−26 μm) was improved by ethylenediamine-N, N'-bis (2-hydroxyphenyl) acetic acid (C-2) and the corresponding interaction mechanism was discussed. Turbidity and microscope measurements show that fine pyrite can be better flocculated to an easily floated size using mixed C-1/C-2 (1:1) reagent scheme pH 8.5. Surface micropolarity results display that the flocculation of fine pyrite using mixed C-1/C-2 is mainly through the hydrophobization of it by reagent adsorption. C-2 and C-1 promoting the adsorption of each other could be implied by the significantly change in the surface roughness of pyrite. FTIR results show the amidation between the –NH– in pre-adsorbed C-1 with the –COO – of C-2. Hydrophobic and bridging flocculation are the primary and secondary factors of the bigger floc size. Considering the possibility of the amidation between –NH– in C-2 and -COS - in C-1 and thus the formation of reticulated polymer, the importance of the bridging flocculation may go up, which needs further study. The better flotation recovery of fine pyrite with mixed C-1/C-2 is consistent with the detection results and deductions.