New role of the conventional foamer sodium N-lauroylsarcosinate as a selective collector for the separation of calcium minerals

Abstract

Fluorite and scheelite are strategic calcium minerals and usually separated through froth flotation. However, the selective separation of fluorite and scheelite remains a great challenge because of their similar physiochemical surface properties. As a green, stable and low-cost surfactant with good biodegradability and foamability, sodium N-lauroylsarcosinate (SNLS) has been widely applied in cosmetics, biological medicine, electroplating and other fields. In this study, SNLS was used as a novel collector for the separation of fluorite from scheelite without any depressant. The flotation tests of binary mixed minerals showed that the selectivity of SNLS for fluorite was higher than that for scheelite at pH 9.0 and a low dosage of 1.1 × 10−5 mol/L. Zeta potential results revealed that SNLS was negatively charged at pH 9.0 and adsorbed on positively charged fluorite surfaces through electrostatic interactions. The results of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Density functional theory (DFT) calculations indicated that the chemical adsorption of the three active O atoms of SNLS on fluorite was stronger than that on scheelite. These O atoms could form a Ca–NLS complex because of the greater Ca density and the higher Ca reactivity on fluorite than on scheelite. Therefore, SNLS has great potential for industrial application in the separation of fluorite from scheelite.