New insights into flotation mechanism of diasporic bauxite from a perspective of liquid film drainage

Abstract

Froth flotation is an effective way to remove silicon and upgrade quality for diasporic bauxite, but its underlying mechanism on microscopic-scale mineral-bubble interaction was poorly understood. In this study, the collision processes of valuable mineral diaspore and main gangue mineral kaolinite with bubbles in collector solution of sodium oleate (NaOL) and dodecylamine hydrochloride (DAH) were recorded to analyze drainage rate of the liquid film (LF). The collector adsorption rate constant and the maximum value of LF drainage rate corresponding to each mineral before and after pretreatment by sodium hexametaphosphate (SHMP) were fitted by an established model. The results showed that NaOL and DAH both can promote LF drainage between the minerals and bubbles, the difference lies in the relationship of drainage rate in NaOL solution was diaspore greater than kaolinite and the opposite in DAH solution. Although SHMP pretreatment has depression effect on collector adsorption rate and LF drainage rate of both minerals in the two solutions, low-dose SHMP can effectively inhibit these parameters of kaolinite in NaOL solution, while effective inhibition for those of diaspore requires high-dose SHMP in DAH solution. The influence mechanism of SHMP in the two systems was further analyzed through active sites difference on minerals interfaces. The present work provides new insight into the underlying mechanism of direct and reverse flotation of diasporic bauxite from the perspective of LF drainage, which will facilitate the targeted development of new collectors in the future.