In the design of a solvent extraction plant for metals it
is necessary to treat the equilibrium data either graphically or
analytically. This enables stagewise calculations to be performed
to explore solvent usage and feed conditions and so optimise on
the cost of recovery of the metal. The present study reviews the
methods of presenting and correlating equilibrium data for solvent
extraction systems involving metals; the limitations of each approach are
highlighted.
The most important example of metal extraction which has been studied
falls into that class involving a metal species, in acid aqueous media,
which displaces protons from the organic extractant during the mass
transfer process. In the typical case of copper extracted by
hydroxyoximes the equilibrium problem reduces to one of modelling a
surface. The concentration of copper in the organic phase is a function
of the concentrations of copper and sulphuric acid in the aqueous phase.
Empirical models seem to be as satisfactory to the engineer as chemical
ones provided the model is used between restricted regions of data.
Practical work has involved the measurement of equilibrium data
for the extraction of zinc and copper by di- (2-ethylhexyl) phosphoric
acid (D2EHPA) in a kerosene diluent. Both the single and binary metal
systems have been studied. The data reported are for feeds between
2-40 g/l zinc, 2-60 g/l copper and 20% V/v D2EHPA. A limited number
of results are also presented for 10% V/v D2EHPA. Specific chemical and
empirical models have been developed to correlate these data. Because
the extractant has a high affinity for zinc in the presence of copper
the binary data can be modelled making the assumption that the interaction
of copper on zinc is negligible. However the effect of zinc on the
limited extraction of copper is significant, the zinc reducing the copper
loading markedly. In this way zinc can be decontaminated of copper.
The methods for presentation of equilibrium data are discussed
and a computer program is given which displays three dimensional
equilibrium surfaces. Classical design procedures for stagewise.
calculations are used against these three dimensional data plots.
Computer programs which allow the investigation of a variety of
operating conditions have also been written.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4194 |
| Date | January 1977 |
| Creators | Forrest , Christopher |
| Contributors | Hughes, M.A. |
| Publisher | University of Bradford, Postgraduate School of Studies in Chemical Engineering, |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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