Computer-assisted calculations of thermodynamic equilibria in the galena-ethyl xanthate system

Calculations show that thermodynamic data can be used to construct pulp chemistry models that satisfactorily describe events in mineral pulps. The introduction of kinetic restrictions, derived from pulp chemistry analysis of full-scale flotation processes, will additionally enhance the models. For the galena-ethyl xanthate system the following results are obtained: (1) the pulp carbonate content is the factor which has the greatest influence on the nature of the surface of the galena/lead mineral in flotation systems; (2) the theoretically calculated upper precipitation limit of Pb(EtX) 2(s) is in good agreement with published data; and (3) Pb(OH)EtX(s) can be formed in carbonate-deficient environments, in a bigger area than Pb(EtX) 2(s), where flotation has been observed while overdosing xanthate. Furthermore, introducing the hypothesis that the surface compound-Pb-EtX is the contact point for the stronger hydrophobizing reagents, the surface compound may be a sort of ternary surface complex.