Secondary lead refining: A model to define acceptable limits for a slag treatment process

摘要

Residues from lead re-refining can be treated in order to recover lead and minimize environmental impacts from slag disposal. The form and the composition of the slag tends to be highly variable. A simulation model has been developed to assess the effects of this variability on the proposed treatment process. The proposed treatment process involves a chemical pre-oxidation step followed by biological oxidation of the slag. The chemical pre-oxidation is not significantly sensitive to input fluctuations. On the other hand, the biological process cannot operate outside a fixed range of input limits. It is a requirement of the chemical pre-oxidation to deliver a reliably consistent feed to the biological process. The aim of the simulation model is to define an acceptable array of input limits to the proposed treatment process by predicting their effect on the critical biological process parameters. The input limits have been defined in terms of a range of acceptable slag compositions. The critical biological process variables have been identified as pH, temperature and ionic strength.