Flotation separation of apatite and potassium feldspar enabled by (tri-n-butyl)-n-tetradecylphosphonium chloride: performance, mechanism, and application in simultaneous reverse flotation

TTPC was first applied for reverse flotation of potassium feldspar from apatite. • TTPC exhibited superior selectivity for potassium feldspar over a wide pH range. • The collection mechanism involved electrostatic interactions and coordination complexation. • TTPC enabled efficient purification of raw phosphate rock via simultaneous reverse flotation. The simultaneous reverse flotation separation of potassium feldspar and dolomite from apatite is of great significance for the high-value development of phosphorus chemical industry. Nevertheless, the lack of effective and highly selective potassium feldspar collectors limits the widespread application of this method. In this study, (tri-n-butyl)-n-tetradecylphosphonium chloride (TTPC) was employed as a collector for the flotation separation of potassium feldspar from apatite. The pure mineral flotation experiments demonstrated that TTPC exhibited excellent collection ability and selectivity for potassium feldspar over a wide pH range (3–8) and low dosage. Further mechanistic analyses, including zeta potential, adsorption capacity, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), revealed that the [-R 4 P] + groups in TTPC could combine with the surface oxygen ion (O 2– ) sites of potassium feldspar, thus selectively adsorbing onto the potassium feldspar surface through electrostatic interactions and coordination complexation. More notably, the synergistic use of TTPC and fatty acid collectors in the simultaneous reverse flotation system effectively reduced the contents of potassium feldspar and dolomite in raw phosphate rock and obtained phosphate concentrate with the phosphorus pentoxide (P 2 O 5 ) grade increased from 23.28% to 27.38% and the recovery of 92.97%, which achieved the purification of phosphate rock and was superior to the conventional ether amine collector. Overall, this work provides new insights into the advanced application of simultaneous reverse flotation for phosphate rock purification. Download: Download high-res image (129KB) Download: Download full-size image