Patent GB-845501-A (GB)
Title: Method of isotope concentration
IPC: B01D59/32
Filed: 1944-10-04
Abstract: A substance, which is enriched in its content of an isotope of an element is obtained by exchanging, in two separate stages at different temperatures, the desired isotope with another isotope of the same element between substances, both of which contain at least one isotope and one of which contains the desired isotope, and which are physically separable from each other, one of the substances being a fluid.  The enriched substance is withdrawn between the stages.  By this process D may be concentrated in either substance of the following pairs by exchange between them ; H2O and an alkyl phosphine, e.g. methyl or ethyl phosphine; H2O and a compound containing an SH group, e.g. methyl, ethyl, or propyl mercaptan, or thiophenol, H2O and acetone. Cl37 may be concentrated in chloroform by exchange between Cl2 and chloroform.  For D exchange catalysts such as Pt., Ni., Co., Fe., Ru., Rh., Pd., Os., Ir., Cr., Mo., W., Re may be used.ALSO:A substance, which is enriched in its content of an isotope of an element is obtained by exchanging, in two separate stages at different temperatures, the desired isotope with another isotope of the same element between substances, both of which contain at least one isotope and one of which contains the desired isotope, and which are physically separable from each other, one of the substances being a fluid.  The enriched substance is withdrawn between the stages.  By this process D may be concentrated in either substance of the following pairs H2 and H2O or NH3; H2O and H2S, HCl, HBr, Hl, phosphine, alkyl, e.g. methyl <PICT:0845501/III/1> <PICT:0845501/III/2> or ethyl, phosphine, compounds containing -SH groups, e.g. methyl, ethyl, or propyl mercaptan, or thiophenol, or acetone; H2SO4 and HCl: S34 may be concentrated in SO2 and NaHSO3: O18 may be concentrated in CO2 or SO2 and H2O: Cl37 may be concentrated in Cl2 and HCl or chloroform; NH4 Cl and HCl, AlCl3 and NaCl: C13 may be concentrated in CO2 and NaHCO3; NaCN and HCN: N15 may be concentrated in NH3 and NH4NO3, NaCN, or NH4OH.  For D exchange catalysts such as Pt., Ni., Co., Fe., Ru., Rh., Pd., Os., Ir., Cr., Mo., W., Re may be used.  H2O and H2S are passed at 25, 27 into cold tower 11 having spaced foraminous plates 13 with packing 15.  The H2O flows down tower 11, which is at 20 DEG C. and under pressure, and D is transferred thereto from the countercurrent of H2S.  The H2O flows through heat-exchanger 21 to tower 17 at 110 DEG C., where D is transferred to the H2S, and is withdrawn at 35 through heatexchanger 21.  The H2S is continuously recycled by pump 38 from the top of cold column 11 through heat-exchanger 23 to the base of the hot column 17.  After flowing through column 17, the H2S passes through heat-exchanger 23, whence condensed water is withdrawn through 45, back to column 11. The condensed liquid from 23 may be passed into column 17 or may be withdrawn as heavy water product at 49.  Alternatively the product may be withdrawn from 29.  A plurality of such pairs of columns may be connected in series with the H2O from 35 passing to next preceding pair of columns, while the product from 49 is passed to the next succeeding pair of columns (see Fig. 4 now shown where column temperatures are 15 DEG  and 80 DEG C.). Alternatively the heavier substance may be continuously recycled through the columns, and the lighter substance passed through.  In Fig. 2 (not shown) the whole exchange is effected in a single tower with one end cold and the other hot.  In Fig. 3 (not shown) the two substances are sprayed into a plurality of pairs of hot and cold (25 DEG  and 200 DEG C.) chambers and the lighter substance is continuously recycled through the two columns.  The heavier substance withdrawn from the cold chamber is divided with part passing to the cold chamber, and part to the hot chamber, of the next succeeding pair of chambers.  The heavier substance withdrawn from the hot chamber is returned to the preceding hot chamber. Normal solids may be used in the process by dissolution in immiscible liquids, e.g. water and CCl4 or ether for NaCl and AlCl3.  The Specification as open to inspection under Section 91 comprises also Fig. 4 (cancelled), a three component exchange is effected where D is transferred from H2O to H2, in a hot tower under pressure at 190-225 DEG C., is transferred from the H2, to liquid NH3 in a cold tower at a minimum 50 DEG C., and from the NH3 to H2O in an equilibrator tower at 130-215 DEG C., whence the heavy water product is recovered.  The H2 and NH3 are continuously recycled in the system and the feed water is used to scrub NH3 from the H2 gas.