Separation of Calcium Isotopes in an Amalgam System

Concentration of the heavy isotopes of calcium by means of the chemical exchange reaction $${}^{46}{\mathrm{Ca}}_{(\mathrm{Hg})}{+}^{40}{\mathrm{Ca}}^{\mathrm{++}}{}_{(\mathrm{solution})}{=}^{40}{\mathrm{Ca}}_{(\mathrm{Hg})}{+}^{46}{\mathrm{Ca}}^{\mathrm{++}}{}_{(\mathrm{solution})}$$ was studied. The reaction was found to be technically feasible as a pre‐enriching process for Calutron feed material; its economic attractiveness depends upon a sufficiently large scale of application. At 25°C, the single‐stage separation factor for isotopes differing by one unit of mass was 1.0013±0.0003 (95% C.I.). The half‐time of exchange of calcium was less than 7 sec. The solubility of calcium in mercury varied from 0.562M at 0°C to 0.908M at 36°C. The integral heat of solution of calcium in mercury was given by the least‐squares equation, —ΔH±0.2(95% C.L.)=45.43–0.56M.