The use of lithium heteropolytungstate as an alternative to bromoform for heavy media separations

This report describes a suggested new procedure for heavy media separation using non-toxic
lithium heteropolytungstate as a replacement for bromoform and other halogenated organic
solvents. This work was carried out as part of the Science Facilities’ Maintenance and
Development of Capability (MaDCap) project. Lithium heteropolytungstate is commonly
known as LST, relating to its composition of lithium, sodium and tungsten.
The report firstly describes heavy liquids that were traditionally used for this purpose and then
details a new heavy media separation methodology using LST.
Results indicate that LST is by far the safest and most efficient heavy liquid suitable for this type
of mineral separation.
Issues regarding LST stability indicate potential contamination through initial sample
preparation methods. A small study indicates that steel swarf from disc milling is responsible for
heteropoly blue contamination of the LST and not pyrite as suggested by the manufacturers. It is
therefore critical that extreme care should be taken when undertaking any sample preparation
prior to heavy liquid separation.