Abstract

Laurionite is the main highly hazardous lead bearing waste in iron ore sintering dust due to its poor stability and high content, while its flotability and flotation separation have not been adequately investigated. In this study, the flotation behavior of laurionite and its interaction with Na2S were investigated in detail to find an economic and promising way for the separation of lead from sintering dust. The flotability and sulfidization flotation of laurionite were examined by micro-flotation experiments, zeta potential measurement, Fourier transform infrared spectroscopy (FT-IR) analysis and X-ray photoelectron spectroscopy (XPS) studies and solution chemistry calculation. The micro-flotation experiments results indicated that Na2S would improve the flotability of laurionite within a moderate dosage, otherwise decrease its float. The negativity of zeta potential observably increased when adding an appreciate amount of Na2S prior to NaBX, indicating a better adsorption of BX− on mineral surface, which would increase the flotation recovery. To figure out the mechanism behind that, the laurionite surface was analyzed by XPS, which found the formation of PbS films after adding Na2S. The FT-IR analysis showed the BX− absorbance on laurionite significantly decreased after treating with high concentration of Na2S. Moreover, the solution chemistry calculations demonstrated that the proper dosage of Na2S could enhance the flotation of laurionite by reduce free lead ion in solution and covered some part of lead mineral surface, which sharply reduced the demand of collectors in flotation. However, the excess S2− would inhibited the adsorption of BX− on laurionite surface since the formation Pb(BX)2 was weaker than PbS. These results did not only expose that the addition of appropriate amount of Na2S could enhance laurionite’s sulfidization flotation, but also provide an effective way to separate laurionite from iron ore sintering dust.

Keywords: 

Sintering dust 

Laurionite 

Sulfidization flotation 

Flotability 

Solution chemistry