Statistical modeling of solvent extraction equilibria: extraction of copper from sulfuric acid and ammoniacal solutions
- PDF / 1,205,917 Bytes
- 12 Pages / 603 x 783 pts Page_size
- 56 Downloads / 214 Views
I.
INTRODUCTION
FEW attempts have been made at developing models
from copper solvent extraction data in terms o f the operating variables involved in the process under a wide range of operating conditions. This situation occurs partly because solvent extraction processes are conventionally designed on the basis o f McCabe-Thiele diagrams. These diagrams depict the equilibrium distribution o f the metal between the organic and aqueous phases by means o f extraction isotherms. Since extraction isotherms are generated for specific operating conditions, usually corresponding to those of a particular solvent extraction process, little attention has been given to generalized mathematical models which can accommodate changes in operating conditions without the need to generate new isotherms. Furthermore, the development o f mechanistic mathematical models for copper solvent extraction processes is a complex and lengthy undertaking. In a rigorous sense, any such model must take into account ionic equilibria in the aqueous phase, and possible complexation phenomena in the organic phase. However, from our present state o f knowledge this cannot be done from theoretical (thermodynamic and kinetic) considerations alone. Consequently, a CARLOS J. VALDES is with Techman Engineering Ltd., Box 2840, Calgary, Alberta, Canada T2P 2M7. W . CHARLES COOPER is with the Department of Metallurgical Engineering, and DAVID W. BACON is with the Department of Chemical Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6. Manuscript submittedJanuary 12, 1982.
METALLURGICAL
TRANSACTIONS B
simplified description o f the physico-chemical behavior o f the systems must be sought. In order to attain a desired metal separation and concentration, the proper design of an industrial solvent extraction system must be carried out from stage to stage with the equilibrium concentrations o f all species calculated from the equilibrium data for the extraction reaction in conjunction with the appropriate material balances. Such a calculation requires a precise knowledge o f the thermodynamic equilibrium constant or of the equilibrium metal distribution in each phase. In addition, the effective design o f a copper solvent extraction process requires a knowledge o f the effects o f multicomponent interphase mass transfer and heterogeneous reaction kinetics, including possible competing reactions. For copper extraction systems o f industrial importance, many o f the data on mass transfer and chemical reaction rates necessary for effective contactor design are not yet known. Considering the commercial importance o f copper solvent extraction and the difficulties associated with a more fundamental approach to the design o f an industrial solvent extraction process for this metal, an empirical modeling study of the solvent extraction of copper from sulfuric acid solution was undertaken. This investigation had the following objectives: (1) to study and to characterize the copper extraction from sulfuric acid and ammoniacal sulfate solutions by mix
Data Loading...
