In mineral processing operations, besides target minerals, slurries often contain various metal ions, including common ones with different valence states such as Pb2+, Cu2+, Fe2+, and Fe3+. These metal ions originate from multiple sources during the flotation process, including the dissolution of co-occurring metal minerals during crushing and grinding, the addition of flotation reagents, and the flotation water. Investigators have long recognized that metal ions significantly affect mineral flotation behavior. Due to physical and chemical interactions, some ions in the slurry will interact with target mineral. If these ions form hydrophobic substances on the mineral surface or increase the active sites between the mineral and collectors or sulfide agent, they will have a positive impact on the flotation process. Conversely, if they produce hydrophilic substances or deplete added collectors and sulfides, they negatively impact mineral enrichment. Meanwhile, metal ions can regulate the electrostatic repulsion between reagents and mineral surfaces in the slurry system, which has a certain impact on the flotation results. This study provides a comprehensive overview of the sources of metal ions in flotation, explores their adsorption characteristics on mineral surfaces, and examines their impact on the flotation process. It provides a theoretical basis for improving mineral flotation processes in the presence of metal ions.