The production of crystals of sodium carbonate heptahydrate or decahydrate

摘要

1496047 Crystallization of sodium carbonates SOLVAY & CIE 9 July 1975 [9 July 1974] 28868/75 Heading C1A The heptahydrate or decahydrate of sodium is crystallized out from a nearly saturated solution of sodium carbonate by cooling with a heat exchanger, the surface in contact with the solution being made of copper or an alloy containing a major part of copper. The temperature difference existing between the copper surface and the solution is preferably below 10‹ C. The heat exchanger may be made entirely of copper or one of its alloys or may be made of another metal coated with copper or copper alloy. The method may be used to recover the hydrated carbonates from the carbonated saline-caustic liquor obtained in the electrolysis of brine in diaphragm cells.