Lead is an engineering material used mainly in the manufacturing of lead-acid batteries for the automotive industry. Lead recovery from exhausted batteries is carried out by the pyrometallurgical route by injecting sulfur the powder reagent through a lance into the lead bath. In this work a mathematical simulation was carried out on the copper drossing process with the software COMSOL 3.4. A kinetic study of the injection process of the lance-kettle system was carried out. The copper concentration profiles were obtained according with the injection rate of the particles. The best conditions for the copper drossing process were an injection rate of 3.31 m/s at 380°C. The modeling results were validated with experimental results obtaining good agreement.