Gas phase extraction of metals from oxides using the ligand acetylacetone
Date
2010-09-20
Authors
Mariba, Epiphania Rumbidzai Memoraine
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Abstract
Gas phase extraction using organic ligands has been gaining interest because it
eliminates many of the problems encountered in conventional mineral processing
methods. This process was successfully used to extract iron using the ligand
acetylacetone from Fe2O3 in a fluidized bed reactor, with above 80% extraction being
achieved after four hours for some experimental conditions. The extraction was
shown to be dependent on temperature, ligand flow rate and the surface area available
for reaction, with extraction increasing as each of the variables was increased.
Chrome could not be extracted successfully, with only a maximum of 12% extraction
being achieved after four hours. It was shown that the process could be used to
successfully separate mixtures containing both iron and chrome oxides by extracting
iron and leaving chrome in the solid phase. Classic shrinking core reaction models
were tested on data obtained to evaluate their fit of experimental data with theoretical
predictions. The chemical reaction limiting shrinking core model was suggested to be
the one that predominantly described the experimental data. There is need however to
develop a model which takes into account the influence of all the variables identified
as affecting the extraction. There is also need to identify ligands which will react
selectively with other metal oxides and not iron in order to the see if the other metals
can also be successfully extracted. Further work should be done on this promising
technology.