S32 The coordination chemistry of extractive metallurgy

Organizers
Emeritus Professor Peter A Tasker, University of Edinburgh, UK
Professor Klaus R Koch, Stellenbosch University, South Africa
Emeritus Professor Karsten Gloe, Technical University Dresden, Germany
Professor Masahiro Goto, Kyushu University, Japan
Group Leader Bruce A Moyer, Oak Ridge National Laboratory, USA
Group Leader Hirokazu Narita, National Institute of Advanced Industrial Science and Technology, Japan
Group Leader, Dave Robinson, CSIRO Mineral Resources, Australia

Keywords of the session

Extractive metallurgy, selectivity, synergism, outer sphere chemistry, anion recognition, hydrometallurgy, refining, purification, metals separation

Scope of the session

The session will draw attention to the importance of coordination chemistry in extractive metallurgy. Increasingly a hydrometallurgical approach is being used for the recovery of metals from primary or secondary sources, replacing the more traditional pyrometallurgical methods. The separation and concentration of metals present in aqueous streams is usually achieved by using strong and selective ligands. Consequently understanding the design features which lead to high selectivity is the key to success in developing new processes. There have been major advances in the last decade, particularly using solvent extraction as the separation technology. This session will deal with:

Anion recognition. Many metals, particularly those of the platinum group, are recovered from aqueous solutions containing complex mixtures of chloridometalate anions, MClxy-. Selective complexation and extraction requires us to address their outer coordination sphere. Speciation and speciation distribution diagrams of precious metal complex anions e.g. Rh(III) and Pt(IV/II) based on novel 195Pt and 103Rh NMR studies of real process solutions.

Outer sphere coordination chemistry. In the non-polar liquids used in solvent extraction, H-bonding between ligands in the outer coordination sphere can be used to stabilize complex formation and it is now possible to tune the strength of extractants and to design synergistic systems using this approach.

Supramolecular chemistry. An understanding of the secondary bonding between extractant molecules and diluents, “modifiers” and phase disengagement agents is often the key to developing effective processes.

Structure of assemblies in solution. There have been major advances in the development of experiment techniques and computational methods to probe the structures of assemblies in solution. Many are transferrable to other applications of coordination chemistry, e.g. catalysis.

F-block coordination chemistry. The separation and recovery of lanthanides and actinides presents particular problems in extractive hydrometallurgy which are associated with their variable coordination numbers and geometries and high hydration energies.