In its natural state, zirconium, which is an important material of construction for nuclear reactors, is associated with hafnium, which has an abnormally high neutron-absorption cross section and must be removed before the zirconium can be used. Refer to Figure 846 for a proposed liquid'liquid extraction process wherein tributyl phosphate (TBP) is used as a solvent for the separation of hafnium from zirconium. One Liter per hour of 5.10-N HNO3 containing 127 g of dissolved Hf and Zr oxides per liter is fed to stage 5 of the 14-stage extraction unit. The feed contains 22.000 g Hf per million g of Zr. Fresh TBP enters stage 14, while scrub water is fed to stage 1. Raffinare is removed at stage 14, while the organic extract phase that is removed at stage 1 goes to a stripping unit. The stripping operation consists of a single contact between fresh water and the organic phase. The following table gives experimental data.

(a) Use these data to fashion a complete material balance for the process.

(b) Check the data for consistency in as many ways as you can.

(c) What is the advantage of running the extractor as shown? Would you recommend that all the stages beused?

STAGEWISE ANALYSES OF MIXER-SETTLER RUN Organic Phase Aqueous Phase (E/Zr) g oxidel liter N HNO3 x (100) liter N HNO3 x (100) g oxide/ (Hf/Zn) Stage 22.2 1 1.95