Rate of removal of lead from copper matte by submerged gas injection

ABSTRACT New lead volatilisation rate and activity data in copper mattes containing low levels of Pb were determined through high-temperature experiments. Measurements on volatilisation rate of lead from mattes (Cu-Fe-S) were carried out at temperatures from 1200 to 1570°C by injection of nitrogen into shallow baths. The concentration of lead in the melts covered a range of 200–6 mg.kg−1. The rate data exhibited first order behaviour with respect to concentration of Pb. The deduced vapour pressure of Pb in the gas was found to be dependent on the concentration of the Pb in melts and in accord with the equilibrium data on mattes at similar temperatures. Increasing temperature had a strong influence on volatilisation rate and total partial pressure of Pb in the gas phase. Matte grade (45–83 wt%) does not have a strong influence on volatilisation rate, but increasing sulphur potential does have a marked impact in supressing the volatilisation rate.