PROCESS FOR SMELTING LEAD ALLOYS AND LEAD BY HEAT REFINING

摘要

The invention relates to a process for smelting lead and lead alloys by heat refining. According to the invention, the process consists in the succession of following operations: charging the liquid raw lead into the refining kettle (1), followed by the coarse removal of copper which is carried out by adding into the lead melting charge brought to a temperature ranging from 360...380°C an amount of wood sawdust in the eye formed by the stirrer (2) until the copper crust is gathered in a sufficient amount for being collected, following the fine copper removal which is carried out by introducing sulphur and pyrite at a melting charge temperature ranging from 330...340°C, followed obligatorily by an amount of tin approximately equal to the copper amount which must be removed in portions of 3 kg, then the ashes are removed, following the alkaline refining by removing the slightly oxidable elements such as As, Sn, Sb and the like, by using portions of 6 kg, at time intervals of 5 min, from a mixture of reagents comprising NaOH and NaNOin a ratio of 1:3, then the ash is removed from the bath and the operation is repeated until the concentrations of the three elements are reduced under the limits provided in the technical specifications, then there follows the operation of removing the zinc from the molten lead bath, which is carried out with the stirrer (2) stopped, at temperatures ranging between 380...400°C by repeated throwing NaOH onto the surface of lead bath until the concentration of zinc is reduced under the value provided in the technical documentation, then the resulting ash is removed from the surface of the lead bath.