Selective separation characteristics of new collector dodecyl dihydroxyethyl methyl ammonium chloride on lepidolite-quartz

Abstract

Lepidolite is one of the main minerals used to extract lithium metal. The efficient flotation separation of lepidolite and quartz has always been a difficult and research hotspot in mineral processing. In this paper, a new cationic collector dodecyl dihydroxyethyl methyl ammonium chloride (2HEAC-12) was innovatively employed to achieve efficient selective separation of lepidolite and quartz. The micro-flotation test was used to investigate the effect of 2HEAC-12 on the flotation separation efficiency of lepidolite and quartz, the contact angle and zeta potential measurement, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis were used to investigate the mechanism of action of 2HEAC-12 on lepidolite and quartz surfaces. The results of micro-flotation test showed that when pH= 3 and the dosage of 2HEAC-12 was 40 mg/L, the flotability difference between lepidolite and quartz was very significant, and lepidolite has good flotability while quartz has weak flotability, so that efficient flotation separation of them could be realized. The results of contact angle tests showed that the surface contact angle of lepidolite increased from 25.62° to 79.56° after 2HEAC-12 treatment, which further confirmed the results of micro-flotation test. The zeta potential test showed that the surface potential of lepidolite is more negative than that of quartz, which is more conducive to the selective adsorption of lepidolite by cationic collector 2HEAC-12. FTIR detection showed that 2HEAC-12 acts on the surface of lepidolite through hydrogen bonding and physical adsorption. XPS analysis further revealed that 2HEAC-12 was adsorbed on the Al-O and Si-O^- sites on the surface of lepidolite through the form of protonated nitrogen (i.e., -N⁺-, -N-). On the contrary, 2HEAC-12 has almost no interaction with quartz, so 2HEAC-12 selectively collected lepidolite. The new 2HEAC-12 collector has higher selectivity than traditional amine collectors in the separation and enrichment of lepidolite ore and has potential industrial application value in the development of lepidolite resources.