GB152766A - Improvements in the manufacture of sulphate of ammonia - Google Patents

Abstract

152,766. Lessing, R. July 21, 1919. Ammonium sulphate.-The colouring-matter usually associated with crystals of ammonium sulphate is removed by agitating the latter, in a detached condition in a clear saturated solution of that salt, maintained slightly acid-if necessary by the addition of sulphuric acid-and floating off the suspended impurities. The agitation may be performed mechanically, or by blowing with air or steam, but preferably it is effected by means of the saturated ammonium-sulphate solution, which enters at a point near the bottom of the conical-shaped treatment vessel containing the crystals. The rapid stream on entering stirs up the crystals, but as the diameter of the vessel increases only the impurities remain suspended. Fig. 1 indicates a saturator A from which crystals are removed to the vessel C by means of steam lift B. A stream of filtered saturated ammonium sulphate enters by pipe d, and is regulated by valve r. The temperature of the liquor throughout the system is maintained at the same temperature as the crystals coming from the saturator by means of steam coils in the storage tank D and the filter F. The clean crystals are discharged periodically on to the drainer H; the liquor collecting in the sump G from which it is raised to tank D by means of an air lift. Au ordinary saturator may also be adapted for the process. Crystals having been deposited, the passage of ammonia is reduced or stopped. A filtered saturated solution of sulphate of ammonia is supplied near the bottom of the saturator, and flows straight through a launder and passes to the filter as previously described.