Selective flotation of brucite from calcite using HEDP-4Na as an inhibitor in a SDS system

Abstract

In this study, the selective adsorption of (1-hydroxyethylidene) bis-phosphonic acid tetrasodium salt (HEDP-4Na) on a calcite surface and its impact on the separation of brucite were examined using a microflotation test, contact angle measurement, zeta potential measurement, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The microflotation test revealed that HEDP-4Na selectively inhibited calcite from brucite at pH 10.5 in the sodium dodecyl sulfonate (SDS) system. Under the dosage condition of 180-mg/L HEDP-4Na, a single-mineral floating difference of 73.79% was achieved between brucite and calcite. The contact angle measurement revealed that HEDP-4Na considerably reduced the contact angle of calcite in the SDS system but only weakly affected the contact angle of brucite. Zeta potential analysis and Fourier transform infrared spectroscopy demonstrated that the HEDP-4Na adsorption interfered with the SDS adsorption on the surface of calcite; however, the HEDP-4Na adsorption had little effect on the SDS adsorption on the surface of brucite. XPS and AFM analyses demonstrated that the selectivity and effect of HEDP-4Na on calcite were considerably stronger than those on brucite and the HEDP-4Na adsorption on the calcite surface was significant and strong.