The objective of this study is to understand the flotation behavior of copper and gold minerals after regrinding the rougher flotation concentrate with a high pyrite content. It was found that low Eh and dissolved oxygen (DO) were produced after regrinding due to the quick consumption of oxygen by the large amount of fresh pyrite surfaces created, resulting in poor flotation of copper and gold and their selectivity against pyrite. A number of methods were used to provide an oxidizing condition, including pre-aeration before flotation, regrinding in an oxidizing condition, and addition of different oxidizing agents during regrinding. It was found that all the oxidizing methods improved the flotation of copper and gold, however, the effectiveness of these methods varied from case to case. This study demonstrates the importance of oxidation during or after regrinding for the flotation of rougher flotation concentrates with high sulfide contents. (C) 2014 Elsevier Ltd. All rights reserved.