Changes in mineral surfaces and gas dispersion can improve a flotation stage without increasing overall copper recovery. This critical review examines these interactions in copper-bearing carbonaceous shales, saline process waters and concentrator tailings. We compare published studies by feed material, operating conditions, measurements and position in the circuit. Copper-shale studies distinguish electrokinetic and wetting responses from the effects of frothers on bubble coalescence. International copper-ore studies examine carbonaceous coatings, clay mineralogy and the influence of water composition on slurry structure and separation. Together, these findings show which links between surface chemistry and hydrodynamics have been measured and which still need to be tested in ore slurries. A worked balance illustrates how upstream copper rejection can offset improved downstream flotation: the break-even loss of approximately 1.12% assumes fixed downstream recovery. We also distinguish the time quantities used in kinetic comparisons and propose a conditional procedure for selecting and validating CFD models. Current and deposited tailings are considered separately because their surface and processing histories differ. The review reports no new experimental recoveries or validated plant simulations.