Effect of sodium diethyldithiocarbamate (DDTC) and xanthate collaborative collection in malachite sulfurization flotation: Enhancement and mechanisms

This study investigates the enhancement of malachite flotation using sodium diethyldithiocarbamate (DDTC) and xanthate as collectors in combination with sodium sulfide (Na₂S). Both collectors promote adsorption on the malachite surface, aiding in forming a copper sulfide (Cu–S) layer that increases surface hydrophobicity and enhances surface roughness, further improving reagent adsorption. Na₂S also stabilizes the Cu–S layer, optimizing flotation performance. Under optimal pH conditions, the combined treatment of Na₂S with DDTC and xanthate achieved the highest flotation recovery (93.15%), outperforming traditional methods. This treatment shifted the malachite contact angle from hydrophilic to hydrophobic, and its zeta potential became increasingly negative. DDTC and xanthate adsorb onto the positively charged copper species through their dithiocarbamate and xanthate ion groups (R-O-C=S−). XPS and FTIR analyses reveal that Na₂S interacts with copper ions, reducing Cu²⁺ to Cu⁺, while DDTC enhances the stability of the copper sulfide layer on the malachite surface. FESEM-EDS analysis shows that the activation products evolved from small aggregate films to dense, cloud-like layers with sulfide deposits, reflecting dynamic surface changes. Flotation experiments demonstrate that DDTC and xanthate improve sulfurization performance, significantly enhancing malachite flotation. These findings indicated that both collectors increased the recovery and provided valuable insights into malachite sulfurization mechanisms.