Sulfur injection to remove copper from recycled lead

This work is focussed on lead decopperising by two techniques: conventional top addition of sulfur and injection of sulfur powder. It is found that th e first method proceeds under equilibrium conditions and the second one dep ends on kinetic considerations. Experiments were carried out using 15 kg lead baths at two temperatures, 34 0 and 380 degreesC. The carrying gas used for the injection trials was nitr ogen with flow rates of 6.3 and 18.6 L min(-1). The results show that the d ecopperising process is more efficient at temperatures close to the melting point of lead for the sulfur top addition process whereas high temperature s produce better copper removal for the injection of sulfur powder. Sulfur injection with the higher nitrogen flow rate (18.6 L min(-1)) produced high er decopperising rates. Thermodynamic and kinetic models are used to simula te this lead refining process.