The empirical correlation described by Eq. (2) can be used to
estimate Cu grade in flotation concentrates. However, attachment
time method is an off line laboratory technique which is manually
performed, and thus is time consuming. This method requires a
skilled operator who changes contact time and visually observes
whether bubble–particle aggregate has occurred. Additionally,
another drawback of this method is that all measurements should
be performed with sized samples having simple mineralogy