GB390980A - A process for the manufacture of ammonium salts - Google Patents

Abstract

<PICT:0390980/III/1> In the production of ammonium salts, e.g. the sulphate or phosphates, aqueous or gaseous ammonia and an acid are continuously introduced into a container, the temperature of the container is controlled by means of a vacuum applied throughout the reaction, the ammonium salt formed is continuously withdrawn and the mother liquor is separated from the crystals of ammonium salt being returned wholly or in part to the container. A saturator or bath 1 is maintained under vacuum by a pump 2. Ammonia is fed through a pipe 4 and perforated distributer ring 8 while sulphuric acid is added through a pipe 6. A stirrer 9 is provided. The heat of reaction causes an evaporation of water at a temperature depending on the vacuum, the water evolved passing through a pipe 3 to a condenser 18. The condensate may be wholly or in part returned to the saturator through pipes 25, 26. Additional water may be supplied through a pipe 19. The ammonium sulphate crystals are pumped by a pump 13 through a pipe 12 into a settler 14. The larger crystals are removed through a pipe 15 to a centrifuging or filtering apparatus, the mother liquor removed in this apparatus returning via a pipe 16 to a trough 22 surrounding the top of the settler. Agitation in the settler causes the smaller crystals to flow into the trough 22 whence they are returned to the saturator through a pipe 17. An open tank 23 provided with a heating coil 24 may be interposed in the line 17 for use when aqueous ammonia or dilute sulphuric acid are employed, the necessary additional heat for evaporation being thereby supplied to the saturator. Vacuums of only a few centimetres of mercury below atmospheric pressure may be employed but preferably a higher vacuum, e.g. a total pressure of not more than 10 cms. of mercury, is employed.