Selective flotation of galena and sphalerite using N-(phosphonomethyl) iminodiacetic acid as an eco-friendly depressant

This study explored the use of N-(phosphonomethyl) iminodiacetic acid (PMIDA) as an eco-friendly depressant for the selective flotation of galena and sphalerite. Microflotation tests were performed to assess the effectiveness of PMIDA. Moreover, the depression mechanism of PMIDA was analyzed through solution chemistry calculations, zeta potential measurements, contact angle determination, X-ray photoelectron spectroscopy, and density-functional theory calculations. Solution chemistry calculations revealed that the presence of PMIDA as PMIDA3− ions in the pulp optimized the depressive effect on sphalerite. Additionally, contact angle results indicated a significant improvement in the surface wettability of sphalerite after PMIDA treatment. Zeta potential measurements revealed that the adsorption capacity of xanthate on the sphalerite surface after PMIDA treatment significantly decreased. X-ray photoelectron spectroscopy analyses indicated that the adsorption of PMIDA on the sphalerite surface was associated with the phosphate functional groups of PMIDA. Density-functional theory simulation data indicated preferential adsorption of PMIDA on the sphalerite surface. These results indicate the potential of PMIDA as a promising depressant to inhibit the flotation of sphalerite and facilitate the selective flotation of galena.