Kinetics of Dissolution of Tenorite in Ammonium Media

In this work, the dissolution kinetics of tenorite (CuO) in a NH4OH-H2O system was studied. The studied temperature range was 5-55 degrees C, ammonium hydroxide concentration between 0.1 and 0.75M, and a particle size range of 5-24 mu m. The stirring speed, pH of the ammonia solution, and various agents were also studied. The results indicated that the leaching of tenorite occurred quickly with a particle size of 5 mu m in a 0.45M solution of NH4OH for a pH value equal to 10.5. Dissolution of CuO also increases as temperature and the concentration of NH4OH increase. For concentrations less than 0.10M, there is almost no leaching tenorite. By decreasing the particle size, the dissolution of CuO increase. Results show the stirring speed had no significant effect on the leaching rate of tenorite for values above 250rpm. Leaching kinetics was analyzed using the model of the surface chemical reaction. The reaction rate was of the order of 2.2 with respect to the concentration of ammonium hydroxide and inversely proportional to the initial particle size. Activation energy of 59kJ/mol was estimated for the temperature range of 5-55 degrees C.