The objective of the present investigation was to obtain, by means of a continuous pilot plant, operating data for the appraisal and design of a full-scale neutralization plant for the treatment of acid mine drainage (AMD) at Brukunga. Laboratory studies of the neutralization process were made to provide a preliminary screening of potential neutralizing reagents and requisite operating levels for chemical addition in the pilot plant. This involved an equilibrium study and laboratory neutralization tests. Thereafter the pilot plant was constructed and operated, and the quality of the resulting effluent examined, for a variety of flow sheets, neutralization reagent input concentrations, reagent consumptions, AMD sources and plant operating conditions. On the basis of the plant operating data so gained, the recommended neutralization method is a two reagent process with inter-stage lagooning, using reactions with introduced caustic mud and then lime, which the laboratory studies have shown to be the best reagents. In the chosen process, caustic mud is mixed with AMD in a first stage to partially neutralize it, and the resulting slurry is fed to a lagoon for separation of dissolved carbon dioxide. The effluent from lagooning is then fully neutralized with lime in a second stage and the precipitated heavy metal hydroxides and basic salts are separated in a second lagoon, with the effluent water being allowed to flow into the local water course. It is also recommended that AMD from on top of the tailings dam be treated in preference to other AMD sources. If other AMD sources have to be treated and they contain a significant amount of ferrous iron, they should be allowed to oxidise by holding before treatment. Parameters of design, AMD retention time and operating pH conditions have been determined for each stage of the full-scale treatment plant. In addition, it is recommended that such a plant be operated automatically, without attendant operating labour. Labour would only be required for plant maintenance and the make-up of chemicals (caustic mud would be made up as a 50% slurry and lime as a 25% slurry, by weight). This would be done weekly and the make-up tanks would have sufficient capacity.