The hydrophobic surface state of talc as influenced by aluminum substitution in the tetrahedral layer
Talc is both an important industrial mineral product recovered by flotation, and also in other cases, a gangue mineral of concern in the flotation of certain sulfide ores, such as the PGM ores in South Africa and in the United States. The talc face surface is naturally hydrophobic with a water sessile drop contact angle of nearly 80 degrees, which accounts for its flotation recovery in one case, and its contamination of sulfide mineral concentrates in other instances. Due to the presence of impurities in the talc structure the surface properties change. One such effect is the presence of aluminum, which can replace silicon in the silica tetrahedral layer of the talc structure. This results in a charge imbalance on the face surface because Si+4 is replaced by Al+3. Sessile drop contact angle and bubble attachment time measurements were made, and these results were compared to the results from molecular dynamics simulations (MDS). The extent of aluminum substitution in the silica tetrahedral layer was considered, and the sessile drop contact angle was found to decrease with increased aluminum content, decreasing from about 80 degrees for no substitution (talc) to 0 degrees for extensive substitution (phlogopite). The water film was found to be stable at the surface of highly aluminum substituted crystals due to the interaction between water molecules and the increased polarity of the surface state. This stable water film restricts the air bubble from attaching to such face surfaces. However, in the absence of aluminum substitution, no interactions between the water molecules and the face surface were observed and the air bubble readily attached to the face surface. This study provides additional understanding of how aluminum substitution in the tetrahedral layer affects the fundamental surface properties of talc, paving the way for the design of improved reagents for talc flotation as an industrial mineral product, and for talc depression in the recovery of sulfide mineral concentrates., their presence at the fresh pyrite surface subsequently facilitates film rupture and attachment of millimeter N2 bubbles, and in this way, improves the flotation of pyrite. The U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, funded the work performed by L.X.D.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1496605
- Report Number(s):
- PNNL-SA-138218
- Journal Information:
- Journal of Colloid and Interface Science, Vol. 536, Issue C; ISSN 0021-9797
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
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