Zirconium, which is used in nuclear reactors, is associated with hafnium, which has a high neutron-absorption cross section and must be removed. Refer to Figure 8.48 for a proposed liquid–liquid extraction process wherein tributyl phosphate (TBP) is used as a solvent for the separation. One L/h 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 at stage 14, while scrub water is fed to stage 1. Raffinate is removed at stage 14, while the organic extract phase removed at stage 1 goes to a stripping unit. The stripping operation consists of a single contact between fresh water and the organic phase. 

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

(b) Check the data for consistency. 

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

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Raffinate Solvent Extraction unit Stage Stage Stage Stage Stage Stage Stage 14 13 8 7 6 5 4 Feed 1.0 liter/h 127 g oxide/h 22,000 ppm Hf Stage 1 Scrub water Stripping unit H₂O strip Aqueous product Figure 8.48 Data for Exercise 8.21.