In this study, the bubble–particle attachment and mineral liberation measurements were used to relate the degree of liberation of Cu minerals with attachment time. The results demonstrated that the presence of highly and moderately liberated Cu minerals resulted in a decreased attachment time. This work showed that a non-linear correlation between the attachment time and Cu grade exists which may be used to predict the concentrate Cu grade. This work should contribute to a better understanding of bubble–particle attachment mechanism occurring during flotation of copper-sulphide ores. This relationship may be used in the future to develop a practical method (without assays) to monitor changing grade for a specified system (flotation plant). It also may be possible to develop a method to infer potential grade if mineralogy samples are available, but not enough samples are available for conventional flotation tests. This requires a significant amount of further work.