Simulated wastewaters (concentrate and tailings thickener overflows), from a future lead-zinc flotation separation plant, were treated for the removal of target metal ions (Zn2+, Pb2+ and Cu2+) and suspended solids (0.1-0.5 g L-1). The ions were adsorbed onto ferric hydroxide precipitates, and then removed by dissolved air flotation (DAF). Best results obtained at bench scale were validated at pilot scale, employing i. 15-20 mg L-1 Fe3+ (chloride salt); ii. Flocculation in two units (rapid mixing - G > 120 s(-1), and slow mixing G = 20-80 s(-1)), with 0.2-0.5 mg L-1 of flocculant (a cationic polyacrylamide); iii. DAF at a saturation pressure of 6 bar and a 20% water recycling rate. The removal of ions between pH 6.5 and 7.5 was very high, reaching separation efficiencies up to 95% for Pb2+ and Cu2+ ions (potential activators of ZnS); the adsorption mechanisms of the uptake of the ions were discussed. The suspended solids (fine particles, < 44 pm) were separated by DAF (89-96%) to concentrations < 0.5 g L-1. For higher solid contents, the formed flocs became larger, difficult-to-float and operating conditions required less flocculant and a higher recycling ratio. These high separation efficiencies allowed reuse of water in the lead/zinc sulphide ore rougher flotation stage, avoiding the activation of ZnS flotation. The pilot DAF unit (1.8-2.4 m(3)h(-1) flow rate) followed an innovative design by enhancing the height/area rate (6.9 m(-1)), compared to conventional cells; it included specially designed and oriented lamellae and a perforated plate to control internal turbulence. These modifications allowed the enhancement of the hydraulic loading capacity up to 15 m(3)m(-2)h(-1) (or 15 m h(-1)), more than double the known value for conventional DAF cells (about 7 m h(-1)). Estimations of general costs for a 300 m(3)h(-1) treatment plant were calculated and the operating costs reached US$ 0.56 m(-3) of treated water. It is believed that this DAF process has a high potential for removing deleterious ions from water at a high removal rate, recycling process water feeding ore flotation plants and minimizing effluent discharge (sometimes polluted).