The flotation with hydroxamate collectors consists of similar
prior basic steps as described with the other processes such as
dispersing of the clay slurry and conditioning with the collector.
The distinguishing features with the hydroxamate collectors are
relative insensitivity to the dispersant type for dispersing clay
slurry and high solids during conditioning and flotation (15). The
conditioning pH is generally maintained between 8 and 10 since
at lower pH values the process is not that efficient and pH higher
than 10 results in excessive frothing which may inhibit effective
separation. In many flotation systems which use hydroxamate
as collectors the optimum pH has been shown to be between
pH 9 and pH 9.5, which is similar to the pKa of hydroxamic
acid (6). The following results (Table 4) indicate that kaolin is
no exception.