Effects of Pure and Modified Nanobubbles on the Reverse Flotation of Kaolinite from Hematite

ABSTRACTThe reverse flotation of kaolinite from hematite suffers from the low kaolinite recovery at neutral or alkaline pH. In this study, the flotation separation of hematite and kaolinite was carried out in the presence and absence of pure nanobubbles (NBs) and modified nanobubbles (MNB) with dodecylamine (DDA) as collector and starch as depressant. The results have shown that in deionized water (DI), kaolinite had a modest flotation recovery of about 65% and starch completely depressed hematite flotation without significantly affecting kaolinite flotation. NBs increased the flotation of kaolinite with exaggerated entrainment loss of fine hematite to the froth. Interestingly, MNB further enhanced the flotation of kaolinite and minimized the unwanted misreporting of hematite. Zeta potential and particle size measurements, together with scanning electron microscopic (SEM) and particle vision and measurement (PVM) were conducted to investigate the underpinning mechanism. It was found that the size of both kaolinite and hematite flocs increased more significantly in MNB water than in NBs water, enhancing the flotation of kaolinite as well as the entrainment depression of hematite. The asynchronous flocculation of hematite and kaolinite in the presence of the MNB and starch could be a potential pathway for better flotation separation of kaolinite and hematite.KEYWORDS: Nanobubblesmodified nanobubblesmineral processingkaolinitehematite Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by the Shandong Provincial Natural Science Foundation [No. ZR2021ME100], and Natural Science Foundation of Hebei Province [No. E2020402081].