1992 Volume 108 Issue 8 Pages 607-610
In order to recover functional double oxides, such as gadolinium gallium garnet (GGG) from its slicing dust by flotation method, the depression of green carborundum (GC) which is an abrasive has been investigated by using various organic colloids.
Corn starch was the most effective depressant for GC. The adsorption of corn starch on GC surface was low in the alkaline pH range and increased as pH decreased. It is considered that the adsorption of corn starch on GC surface through hydrogen bonding between hydrogen atoms in corn starch molecule and oxygen atoms on GC surface becomes favorable as pH decreases, because the electrostatic repulsion between corn starch and GC decreases owing to the decrease of negative charge on GC surface. On the other hand, the adsorption of corn starch on GGG surface was high in the alkaline pH range and low in the acidic pH range. The decrease in the adsorption of corn starch on GGG in the acidic pH range may be explained by the reason that hydrogen ions are strongly adsorbed on the oxygen sites on GGG surface so that corn starch can not be adsorbed. Also, the adsorption of corn starch in the acidic pH range was further decreased by the specific adsorption of sulfate ions. Accordingly, corn starch may be adsorbed on GC surface in preference to GGG surface in the acidic pH range, particularly, when sulfuric acid is used as a pH regulator.
