Contents 1 The Possibility of using Solvent - Solvent Extraction

This report investigates the use of solvent-solvent extraction for the secondary concentration of lead and thorium. The extraction reagents investigated in this report are: For the lead extraction: diethlyammonium diethyldithiocarbamate (DDDC) For the thorium extraction: trioctylphosphinc oxide (TOPO) and di-(2-ethylhexyl)phosphoric add (HDEHP). For all of the extractions 2-octanone was used as the organic solvent. By scaling the results of the experiments described in this report it is expected that 70-80% of the lead and thorium m the 8 litres of SUF eluate, could be extracted sequentially into two 400ml samples of organic solvent, one containing the extracted lead and one containing the extracted thorium. To assay the extracted lead and thorium it is proposed that & larger version of the existing f3-a delayed coincidence scintillation counters be developed. With this larger counter operational it is anticipated that the secondary concentration and assay of lead from the SUF eluate can be achieved. Although the secondary concentration is as good for thorium, further work is needed to enable its assay since a back-extraction technique for thorium has not yet been-found.