Abstract
The effect of Al3+ in backwater on the flotation of diaspore bauxite was investigated by micro-flotation tests and the underlying mechanisms were investigated by inductively coupled plasma (ICP) measurement, zeta potential measurements, solution chemistry analyses, and synchrotron near edge X-ray absorption fine structure (NEXAFS) analyses. The ICP measurement results show the concentration of Al3+ in backwater was up to 1 × 10−4 mol/L. The micro-flotation results indicated that backwater Al3+ reduced the flotation recovery of diaspore and improved the flotation recovery of kaolinite at pH 9, which was the pH value used in the industrial flotation. The adsorption of Al3+ species changed the zeta potential, the Al atomic abundance, and the number of active sites on the mineral surface. In particular, the result of solution chemistry analyses and synchrotron NEXAFS analyses show that the Al3+ in backwater was adsorbed on the mineral surface in the form of Al(OH)3 (s), and the bond of –Al–O–Al–(OH)2 or –Al/Si–O–Al–(OH)2 was formed at pH 9. It changed the intensity of hydrogen bond force between minerals and collectors, and resulted in the depression of diaspore flotation and the activation of kaolinite flotation. This study can be used to guide the application of backwater in the flotation of diaspore bauxite in industry.
Highlights
It was reported that, until 2015, the bauxite ore reserves in China was 4.71 billion tons [1], and the majority was diaspore bauxite
The Al atomic abundance (Al molecules divided by the total number of molecules on the mineral surface) of diaspore surface is higher than that of kaolinite surface according to the molecular model
It indicated that Al3+ activated the flotation of diaspore in acidic condition and intensely inhibited the flotation of diaspore in weak alkaline condition
Summary
Until 2015, the bauxite ore reserves in China was 4.71 billion tons [1], and the majority was diaspore bauxite. Diaspore bauxite is unsuitable for direct extraction of alumina with Bayer process due to the low ration of alumina to silica (A/S). In the past few decades, the Bayer-mineral processing method has been developed by Chinese researchers to make better use of diaspore bauxite ore. The Al atomic abundance (Al molecules divided by the total number of molecules on the mineral surface) of diaspore surface is higher than that of kaolinite surface according to the molecular model. It was considered that the atomic abundance of Al on the mineral surface was key to bauxite flotation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
