Wettability of quartz particles at varying conditions on the basis of the measurement of relative wetting contact angles and their flotation behaviour
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Northeastern University
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Shuling Gao   

Northeastern University, 11 3 alley Wenhua Road Heping District Shenyang City Liaoning Province, 110819 Shenyang, China
Physicochem. Probl. Miner. Process. 2019;55(1):278-289
In this paper, on the basis of a modified Washburn equation, the squared incremental pressure due to liquid rising vs. time were measured instead of wicking distances before reaching equilibrium, and the relative wetting contact angles (RWCA) were applied to characterize the surface wettability of quartz particles conditioned at different concentrations of flotation reagents. Combined with the flotation experiments on quartz particles at corresponding conditions, the relationship between flotation recoveries and RWCA was analysed, which proves that RWCA can characterize the surface wettability of quartz particles accurately. The results also showed that the best reagent conditions for floating quartz are pH 12.0, a Ca2+ concentration of 1×10-3 mol/dm3 and a sodium oleate concentration of 0.75×10-3 mol/dm3, where the recovery of quartz is 86%. The surface tension of the filtrate of the pulp was determined by a fully-automatic tensiometer as well. Based on the measured values of RWCA and surface tension, the free energy changes (∆G) before and after the adhesion of bubbles and particles per unit area at corresponding situations were calculated, respectively. The trends of ∆G varying with the concentrations of reagents were in close accordance with those of RWCA and the flotation recoveries, proving that it is more likely for particles having bigger contact angles to adhere to bubbles, resulting in a higher flotation recovery. These results give a more feasible and accurate approach to analysing the surface wettability and floatability of fine particles.
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