Chemical Engineering Studies on the Decomposition of Amalgam in a Packed Tower in the Chlor-caustic Industry

Abstract

Part I. The kinetics of amalgam decomposition in the case of a local cell consisting of Na-Hg (Y)/NaOH aq. (X)/H₂-graphite, with emphasis on the hydrogen overpotential, chemical engineering considerations of the decomposition tower, and the design of the tower are described. These studies involve representations concerning the H.T.U. and the N.T.U. of the amalgam decomposition tower which differs from common packed towers where the diffusion process is controlling. Part. II. The amalgam decomposition tower is a kind of packed column. The height is given by the product of H.T.U. and N.T.U., where H.T.U. and N.T.U. are as follows: H.T.U.=1/K·M/S (1) N.T.U.=-∫y₀y₁·dy/E-πₕ⁰ (2) and 1/K=1/KᴀY+1/KH+1/KFᴷ≅1/KH+1/KFᴷ (3) Thus, the H.T.U. is, determined by the geometry which occurs between the graphite packings and the amalgam drops, and the N.T.U. is determined by the hydrogen overpotential of the graphite. Hence, the performance of the graphite packings may be estimated from these physical and electrochemical characteristics if they are established empirically.