ABSTRACT
The most utilized of separation techniques in commercial practice is probably distillation, which employs volatility differentiation. Slurry extraction utilizes the latter type of shape-selectivity. Specifically, urea, which crystallizes to form n-paraffin complexes, and thiourea, whose adduct crystal structure contains somewhat bulkier guest molecules, are host substances of interest. The selectivity of such adducts for the guest substances they contain is very high, but if the solid is used as such, continuous solids manipulation on an industrial scale becomes difficult. The slurry systems which have been studied in the laboratory lead to continuous, countercurrent, multistage separation of liquid hydrocarbon mixtures. Slurry extraction involves equilibration of complexing solid simultaneously with hydrocarbon liquids and the solution phase, mainly slurry solvent. The chapter describes the effects of this multiple equilibration on the net separation. Qualitatively, it is found that the rates of adduct precipitation and exchange decrease sharply as the solubility of hydrocarbon in slurry solution approaches zero.
